diff --git a/.github/workflows/ci_steps.yml b/.github/workflows/ci_steps.yml
index 2554bdb9..42734c56 100644
--- a/.github/workflows/ci_steps.yml
+++ b/.github/workflows/ci_steps.yml
@@ -10,70 +10,32 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ['2.6']
+        ruby: ['3.3.10']
 
     env:
-      QT_SELECT: qt5
-      OPENSSL_CONF: /dev/null
       LANG: C.UTF-8
       LC_ALL: C.UTF-8
 
     steps:
-      - name: Fix APT for EOL Debian
-        run: |
-          if grep -q buster /etc/apt/sources.list 2>/dev/null; then
-            echo "deb [trusted=yes] http://archive.debian.org/debian buster main" > /etc/apt/sources.list
-            echo "deb [trusted=yes] http://archive.debian.org/debian-security buster/updates main" >> /etc/apt/sources.list
-          fi
-          echo 'Acquire::Check-Valid-Until "false";' > /etc/apt/apt.conf.d/99archive
-          echo 'Acquire::AllowInsecureRepositories "true";' >> /etc/apt/apt.conf.d/99archive
-
       - name: Install system packages
         run: |
           apt-get update -qq
           apt-get install -y --no-install-recommends \
-            git ca-certificates curl bzip2 \
-            build-essential g++ make \
-            qt5-qmake qtbase5-dev libqt5webkit5-dev qtchooser \
-            xvfb xauth libfontconfig1 libfreetype6 libxrender1 libxext6 libx11-6 \
+            git ca-certificates curl \
+            build-essential \
+            chromium chromium-driver \
             libssl-dev zlib1g-dev
 
-      - name: Setup qmake
-        run: |
-          mkdir -p /usr/share/qtchooser
-          echo "/usr/lib/x86_64-linux-gnu/qt5/bin" > /usr/share/qtchooser/qt5.conf
-          echo "/usr/lib/x86_64-linux-gnu" >> /usr/share/qtchooser/qt5.conf
-          ln -sf /usr/lib/x86_64-linux-gnu/qt5/bin/qmake /usr/bin/qmake 2>/dev/null || true
-          qmake --version
-
-      - name: Install PhantomJS
-        run: |
-          curl -L -o phantomjs.tar.bz2 "https://github.com/Medium/phantomjs/releases/download/v2.1.1/phantomjs-2.1.1-linux-x86_64.tar.bz2"
-          tar xf phantomjs.tar.bz2 --wildcards '*/bin/phantomjs' --strip-components=2
-          mv phantomjs /usr/local/bin/
-          rm phantomjs.tar.bz2
-          phantomjs --version || echo "PhantomJS installed"
-
       - name: Checkout
         uses: actions/checkout@v4
 
       - name: Install Bundler
-        run: gem install bundler -v '< 2'
+        run: gem install bundler
 
       - name: Bundle install
-        run: |
-          bundle config set force_ruby_platform true
-          echo "gem 'ffi', '~> 1.15.0'" >> Gemfile
-          echo "gem 'regexp_parser', '~> 1.8'" >> Gemfile
-          echo "gem 'public_suffix', '~> 4.0'" >> Gemfile
-          echo "gem 'capybara', '~> 3.35.0'" >> Gemfile
-          echo "gem 'addressable', '~> 2.7.0'" >> Gemfile
-          echo "gem 'nokogiri', '~> 1.12.0'" >> Gemfile
-          echo "gem 'mini_mime', '~> 1.1.0'" >> Gemfile
-          echo "gem 'rack', '~> 2.2.0'" >> Gemfile
-          bundle install --jobs 4 --retry 3
-        env:
-          QMAKE: /usr/bin/qmake
+        run: bundle install --jobs 4 --retry 3
 
       - name: Run tests
-        run: xvfb-run -a bundle exec rspec spec
+        run: bundle exec rspec spec
+        env:
+          CHROME_BIN: /usr/bin/chromium
diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 00000000..adb7a54f
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,5 @@
+plugins:
+  - rubocop-rspec
+  - rubocop-capybara
+
+inherit_from: .rubocop_todo.yml
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
new file mode 100644
index 00000000..b9a95755
--- /dev/null
+++ b/.rubocop_todo.yml
@@ -0,0 +1,248 @@
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2026-02-26 07:29:32 UTC using RuboCop version 1.84.2.
+# The point is for the user to remove these configuration records
+# one by one as the offenses are removed from the code base.
+# Note that changes in the inspected code, or installation of new
+# versions of RuboCop, may require this file to be generated again.
+
+# Offense count: 1
+# Configuration parameters: AllowComments, AllowNil.
+Lint/SuppressedException:
+  Exclude:
+    - 'lib/billy/browsers/capybara.rb'
+
+# Offense count: 1
+# Configuration parameters: AllowKeywordBlockArguments.
+Lint/UnderscorePrefixedVariableName:
+  Exclude:
+    - 'lib/billy/cache.rb'
+
+# Offense count: 16
+# Configuration parameters: AllowedMethods, AllowedPatterns, CountRepeatedAttributes.
+Metrics/AbcSize:
+  Max: 54
+
+# Offense count: 1
+# Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns, inherit_mode.
+# AllowedMethods: refine
+Metrics/BlockLength:
+  Max: 69
+
+# Offense count: 2
+# Configuration parameters: CountBlocks, CountModifierForms.
+Metrics/BlockNesting:
+  Max: 4
+
+# Offense count: 2
+# Configuration parameters: CountComments, CountAsOne.
+Metrics/ClassLength:
+  Max: 121
+
+# Offense count: 2
+# Configuration parameters: AllowedMethods, AllowedPatterns.
+Metrics/CyclomaticComplexity:
+  Max: 11
+
+# Offense count: 15
+# Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns.
+Metrics/MethodLength:
+  Max: 45
+
+# Offense count: 1
+# Configuration parameters: CountKeywordArgs, MaxOptionalParameters.
+Metrics/ParameterLists:
+  Max: 9
+
+# Offense count: 2
+# Configuration parameters: AllowedMethods, AllowedPatterns.
+Metrics/PerceivedComplexity:
+  Max: 14
+
+# Offense count: 1
+Naming/AccessorMethodName:
+  Exclude:
+    - 'spec/support/test_server.rb'
+
+# Offense count: 1
+# Configuration parameters: ExpectMatchingDefinition, CheckDefinitionPathHierarchy, CheckDefinitionPathHierarchyRoots, Regex, IgnoreExecutableScripts, AllowedAcronyms.
+# CheckDefinitionPathHierarchyRoots: lib, spec, test, src
+# AllowedAcronyms: CLI, DSL, ACL, API, ASCII, CPU, CSS, DNS, EOF, GUID, HTML, HTTP, HTTPS, ID, IP, JSON, LHS, QPS, RAM, RHS, RPC, SLA, SMTP, SQL, SSH, TCP, TLS, TTL, UDP, UI, UID, UUID, URI, URL, UTF8, VM, XML, XMPP, XSRF, XSS
+Naming/FileName:
+  Exclude:
+    - 'Rakefile.rb'
+    - 'lib/puffing-billy.rb'
+
+# Offense count: 1
+# Configuration parameters: NamePrefix, ForbiddenPrefixes, AllowedMethods, MethodDefinitionMacros, UseSorbetSigs.
+# NamePrefix: is_, has_, have_, does_
+# ForbiddenPrefixes: is_, has_, have_, does_
+# AllowedMethods: is_a?
+# MethodDefinitionMacros: define_method, define_singleton_method
+Naming/PredicatePrefix:
+  Exclude:
+    - 'spec/**/*'
+    - 'lib/billy/proxy_request_stub.rb'
+
+# Offense count: 4
+# Configuration parameters: EnforcedStyle, CheckMethodNames, CheckSymbols, AllowedIdentifiers, AllowedPatterns.
+# SupportedStyles: snake_case, normalcase, non_integer
+# AllowedIdentifiers: TLS1_1, TLS1_2, capture3, iso8601, rfc1123_date, rfc822, rfc2822, rfc3339, x86_64
+Naming/VariableNumber:
+  Exclude:
+    - 'spec/lib/proxy_spec.rb'
+
+# Offense count: 23
+RSpec/Be:
+  Exclude:
+    - 'spec/lib/billy/proxy_request_stub_spec.rb'
+
+# Offense count: 29
+# Configuration parameters: Prefixes, AllowedPatterns.
+# Prefixes: when, with, without
+RSpec/ContextWording:
+  Exclude:
+    - 'spec/lib/billy/cache_spec.rb'
+    - 'spec/lib/billy/handlers/cache_handler_spec.rb'
+    - 'spec/lib/billy/handlers/proxy_handler_spec.rb'
+    - 'spec/lib/billy/proxy_request_stub_spec.rb'
+    - 'spec/lib/proxy_spec.rb'
+
+# Offense count: 50
+# Configuration parameters: CountAsOne.
+RSpec/ExampleLength:
+  Max: 22
+
+# Offense count: 7
+RSpec/ExpectInHook:
+  Exclude:
+    - 'spec/lib/billy/handlers/proxy_handler_spec.rb'
+
+# Offense count: 8
+# Configuration parameters: Max, AllowedIdentifiers, AllowedPatterns.
+RSpec/IndexedLet:
+  Exclude:
+    - 'spec/lib/billy/cache_spec.rb'
+    - 'spec/lib/billy/ssl/authority_spec.rb'
+    - 'spec/lib/billy/ssl/certificate_chain_spec.rb'
+    - 'spec/lib/billy/ssl/certificate_spec.rb'
+
+# Offense count: 20
+# Configuration parameters: AssignmentOnly.
+RSpec/InstanceVariable:
+  Exclude:
+    - 'spec/lib/billy/watir/watir_spec.rb'
+    - 'spec/lib/proxy_spec.rb'
+
+# Offense count: 15
+RSpec/LetSetup:
+  Exclude:
+    - 'spec/lib/billy/handlers/stub_handler_spec.rb'
+    - 'spec/lib/proxy_spec.rb'
+
+# Offense count: 62
+# Configuration parameters: .
+# SupportedStyles: have_received, receive
+RSpec/MessageSpies:
+  EnforcedStyle: receive
+
+# Offense count: 41
+RSpec/MultipleExpectations:
+  Max: 11
+
+# Offense count: 10
+# Configuration parameters: AllowSubject.
+RSpec/MultipleMemoizedHelpers:
+  Max: 15
+
+# Offense count: 79
+# Configuration parameters: EnforcedStyle, IgnoreSharedExamples.
+# SupportedStyles: always, named_only
+RSpec/NamedSubject:
+  Exclude:
+    - 'spec/lib/billy/handlers/proxy_handler_spec.rb'
+    - 'spec/lib/billy/handlers/request_handler_spec.rb'
+    - 'spec/lib/billy/proxy_connection_spec.rb'
+    - 'spec/lib/billy/proxy_request_stub_spec.rb'
+
+# Offense count: 12
+# Configuration parameters: AllowedGroups.
+RSpec/NestedGroups:
+  Max: 5
+
+# Offense count: 2
+RSpec/RepeatedExampleGroupBody:
+  Exclude:
+    - 'spec/lib/billy/handlers/request_handler_spec.rb'
+
+# Offense count: 10
+# Configuration parameters: CustomTransform, IgnoreMethods, IgnoreMetadata, InflectorPath, EnforcedInflector.
+# SupportedInflectors: default, active_support
+RSpec/SpecFilePathFormat:
+  Exclude:
+    - '**/spec/routing/**/*'
+    - 'spec/lib/billy/handlers/cache_handler_spec.rb'
+    - 'spec/lib/billy/handlers/handler_spec.rb'
+    - 'spec/lib/billy/handlers/proxy_handler_spec.rb'
+    - 'spec/lib/billy/handlers/request_handler_spec.rb'
+    - 'spec/lib/billy/handlers/request_log_spec.rb'
+    - 'spec/lib/billy/handlers/stub_handler_spec.rb'
+    - 'spec/lib/billy/resource_utils_spec.rb'
+    - 'spec/lib/billy/ssl/authority_spec.rb'
+    - 'spec/lib/billy/ssl/certificate_chain_spec.rb'
+    - 'spec/lib/billy/ssl/certificate_spec.rb'
+
+# Offense count: 42
+RSpec/StubbedMock:
+  Exclude:
+    - 'spec/lib/billy/handlers/cache_handler_spec.rb'
+    - 'spec/lib/billy/handlers/proxy_handler_spec.rb'
+    - 'spec/lib/billy/handlers/request_handler_spec.rb'
+    - 'spec/lib/billy/handlers/stub_handler_spec.rb'
+
+# Offense count: 4
+RSpec/SubjectDeclaration:
+  Exclude:
+    - 'spec/lib/billy/proxy_connection_spec.rb'
+    - 'spec/lib/billy/proxy_request_stub_spec.rb'
+
+# Offense count: 3
+RSpec/SubjectStub:
+  Exclude:
+    - 'spec/lib/billy/handlers/proxy_handler_spec.rb'
+    - 'spec/lib/billy/handlers/request_handler_spec.rb'
+
+# Offense count: 6
+# Configuration parameters: IgnoreNameless, IgnoreSymbolicNames.
+RSpec/VerifiedDoubles:
+  Exclude:
+    - 'spec/lib/billy/handlers/proxy_handler_spec.rb'
+    - 'spec/lib/billy/handlers/request_handler_spec.rb'
+    - 'spec/lib/billy/handlers/stub_handler_spec.rb'
+
+# Offense count: 19
+# Configuration parameters: AllowedConstants.
+Style/Documentation:
+  Enabled: false
+
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+Style/IfUnlessModifier:
+  Exclude:
+    - 'lib/billy/handlers/proxy_handler.rb'
+
+# Offense count: 4
+# Configuration parameters: AllowedMethods.
+# AllowedMethods: respond_to_missing?
+Style/OptionalBooleanParameter:
+  Exclude:
+    - 'lib/billy/cache.rb'
+    - 'lib/billy/proxy.rb'
+    - 'spec/support/test_server.rb'
+
+# Offense count: 22
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowHeredoc, AllowURI, AllowQualifiedName, URISchemes, AllowRBSInlineAnnotation, AllowCopDirectives, AllowedPatterns, SplitStrings.
+# URISchemes: http, https
+Layout/LineLength:
+  Max: 158
diff --git a/Dockerfile b/Dockerfile
index fe2ff43c..d6f27e6a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,14 +1,16 @@
-FROM ruby:1.9.3
+FROM ruby:3.3.10
+
+RUN apt-get update -qq && \
+    apt-get install -y --no-install-recommends \
+      git ca-certificates curl \
+      build-essential \
+      chromium chromium-driver \
+      libssl-dev zlib1g-dev && \
+    rm -rf /var/lib/apt/lists/*
+
+ENV CHROME_BIN=/usr/bin/chromium
 
-RUN apt-get update -y
-RUN apt-get install -y qt5-default libqt5webkit5-dev gstreamer1.0-plugins-base gstreamer1.0-tools gstreamer1.0-x
 RUN gem install bundler
-RUN \
-    export PHANTOMJS_VERSION='2.1.1'                                             && \
-    export PHANTOMJS_URL='https://github.com/Medium/phantomjs/releases/download/v2.1.1/phantomjs-2.1.1-linux-x86_64.tar.bz2' && \
-    wget -q ${PHANTOMJS_URL}                                                     && \
-    tar xfv phantomjs-${PHANTOMJS_VERSION}-linux-x86_64.tar.bz2                  \
-      -C /usr/bin --wildcards */bin/phantomjs --strip-components=2
 RUN mkdir -p /app
 COPY . /app
 RUN cd /app && bundle install
diff --git a/Gemfile b/Gemfile
index b52c54e0..c3b7ebde 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 
 # Specify your gem's dependencies in puffing-billy.gemspec
diff --git a/Guardfile b/Guardfile
index a3fbf805..464f84ba 100644
--- a/Guardfile
+++ b/Guardfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A sample Guardfile
 # More info at https://github.com/guard/guard#readme
 
@@ -9,7 +11,9 @@ guard 'rspec', version: 2 do
   # Rails example
   watch(%r{^app/(.+)\.rb$})                           { |m| "spec/#{m[1]}_spec.rb" }
   watch(%r{^app/(.*)(\.erb|\.haml)$})                 { |m| "spec/#{m[1]}#{m[2]}_spec.rb" }
-  watch(%r{^app/controllers/(.+)_(controller)\.rb$})  { |m| ["spec/routing/#{m[1]}_routing_spec.rb", "spec/#{m[2]}s/#{m[1]}_#{m[2]}_spec.rb", "spec/acceptance/#{m[1]}_spec.rb"] }
+  watch(%r{^app/controllers/(.+)_(controller)\.rb$})  do |m|
+    ["spec/routing/#{m[1]}_routing_spec.rb", "spec/#{m[2]}s/#{m[1]}_#{m[2]}_spec.rb", "spec/acceptance/#{m[1]}_spec.rb"]
+  end
   watch(%r{^spec/support/(.+)\.rb$})                  { 'spec' }
   watch('config/routes.rb')                           { 'spec/routing' }
   watch('app/controllers/application_controller.rb')  { 'spec/controllers' }
@@ -19,5 +23,7 @@ guard 'rspec', version: 2 do
 
   # Turnip features and steps
   watch(%r{^spec/acceptance/(.+)\.feature$})
-  watch(%r{^spec/acceptance/steps/(.+)_steps\.rb$})   { |m| Dir[File.join("**/#{m[1]}.feature")][0] || 'spec/acceptance' }
+  watch(%r{^spec/acceptance/steps/(.+)_steps\.rb$}) do |m|
+    Dir[File.join("**/#{m[1]}.feature")][0] || 'spec/acceptance'
+  end
 end
diff --git a/README.md b/README.md
index 8abd7901..6af5f076 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
-# Puffing Billy [![Gem Version](https://badge.fury.io/rb/puffing-billy.svg)](https://badge.fury.io/rb/puffing-billy) [![Build Status](https://travis-ci.org/oesmith/puffing-billy.svg?branch=master)](https://travis-ci.org/oesmith/puffing-billy)
+# Puffing Billy [![Gem Version](https://badge.fury.io/rb/puffing-billy.svg)](https://badge.fury.io/rb/puffing-billy) [![Build Status](https://github.com/oesmith/puffing-billy/actions/workflows/ci_steps.yml/badge.svg)](https://github.com/oesmith/puffing-billy/actions/workflows/ci_steps.yml)
 
 A rewriting web proxy for testing interactions between your browser and
-external sites. Works with ruby + rspec.
+external sites. Works with ruby (>= 3.3.10) + rspec.
 
 Puffing Billy is like [webmock](https://github.com/bblimke/webmock) or
 [VCR](https://github.com/vcr/vcr), but for your browser.
@@ -30,6 +30,11 @@ end
 You can also record HTTP interactions and replay them later. See
 [caching](#caching) below.
 
+## Requirements
+
+- Ruby >= 3.3.10
+- Chrome/Chromium (recommended) or Firefox for browser-based tests
+
 ## Installation
 
 Add this line to your application's Gemfile:
@@ -53,20 +58,14 @@ In your `rails_helper.rb`:
 ```ruby
 require 'billy/capybara/rspec'
 
-# select a driver for your chosen browser environment
-Capybara.javascript_driver = :selenium_billy # Uses Firefox
-# Capybara.javascript_driver = :selenium_chrome_billy
-# Capybara.javascript_driver = :selenium_chrome_headless_billy
-# Capybara.javascript_driver = :apparition_billy
-# Capybara.javascript_driver = :webkit_billy
-# Capybara.javascript_driver = :poltergeist_billy
+# Select a driver for your chosen browser environment.
+# The :selenium_chrome_billy and :selenium_chrome_headless_billy drivers
+# respect the CHROME_BIN environment variable for custom Chrome/Chromium paths.
+Capybara.javascript_driver = :selenium_billy                    # Firefox
+# Capybara.javascript_driver = :selenium_chrome_billy           # Chrome
+# Capybara.javascript_driver = :selenium_chrome_headless_billy  # Chrome (headless, recommended for CI)
 ```
 
-> __Note__: `:poltergeist_billy` doesn't support proxying any localhosts, so you must use
-`:webkit_billy`, `:apparition_billy`, or a custom headless selenium registration for
-headless specs when using puffing-billy for other local rack apps.
-See [this phantomjs issue](https://github.com/ariya/phantomjs/issues/11342) for any updates.
-
 ### Setup for Watir
 
 In your `rails_helper.rb`:
@@ -74,10 +73,19 @@ In your `rails_helper.rb`:
 ```ruby
 require 'billy/watir/rspec'
 
-# select a driver for your chosen browser environment
-@browser = Billy::Browsers::Watir.new :firefox
-# @browser = Billy::Browsers::Watir.new = :chrome
-# @browser = Billy::Browsers::Watir.new = :phantomjs
+# Basic usage
+@browser = Billy::Browsers::Watir.new :chrome
+# @browser = Billy::Browsers::Watir.new :firefox
+
+# CI / containerized environments (Docker, GitHub Actions)
+# Pass Chrome options to enable headless mode and container-safe flags.
+# Set CHROME_BIN if Chromium is not at the default google-chrome path.
+options = Selenium::WebDriver::Chrome::Options.new
+options.add_argument('--headless=new')
+options.add_argument('--no-sandbox')
+options.add_argument('--disable-dev-shm-usage')
+options.binary = ENV['CHROME_BIN'] if ENV['CHROME_BIN']
+@browser = Billy::Browsers::Watir.new :chrome, options: options
 ```
 
 ### In your tests (Capybara/Watir)
@@ -188,7 +196,7 @@ And in steps:
 
 ```ruby
 Before('@billy') do
-  Capybara.current_driver = :poltergeist_billy
+  Capybara.current_driver = :selenium_chrome_headless_billy
 end
 
 And /^a stub for google$/ do
@@ -286,7 +294,7 @@ Billy.configure do |c|
   c.non_whitelisted_requests_disabled = false
   c.cache_path = 'spec/req_cache/'
   c.certs_path = 'spec/req_certs/'
-  c.proxy_host = 'example.com' # defaults to localhost
+  c.proxy_host = 'example.com' # defaults to 127.0.0.1
   c.proxy_port = 12345 # defaults to random
   c.proxied_request_host = nil
   c.proxied_request_port = 80
@@ -648,13 +656,11 @@ this gem.
 
 ### Google Chrome Headless example
 
-Google Chrome/Chromium is capable to run as a test browser with the new
-headless mode which is not able to handle the deprecated
-`--ignore-certificate-errors` flag. But the headless mode is capable of
-handling the user PKI certificate store.  So you just need to import the
-runtime Puffing Billy certificate authority on your system store, or generate a
-new store for your current session. The following examples demonstrates the
-former variant:
+Puffing Billy registers the `:selenium_chrome_headless_billy` driver using
+Chrome's `headless=new` mode (available since Chrome 112). This mode supports
+the user PKI certificate store, so you need to import the Puffing Billy
+certificate authority into your system or session store. The following example
+demonstrates how to do that at test suite startup:
 
 ```ruby
 # Install the fabulous `os` gem first
@@ -742,4 +748,3 @@ custom on-after hook.
 ## TODO
 
 1. Integration for test frameworks other than rspec.
-2. Show errors from the EventMachine reactor loop in the test output.
diff --git a/Rakefile b/Rakefile
old mode 100644
new mode 100755
index 61b03388..19d5d343
--- a/Rakefile
+++ b/Rakefile
@@ -1,2 +1,4 @@
 #!/usr/bin/env rake
+# frozen_string_literal: true
+
 require 'bundler/gem_tasks'
diff --git a/bin/proxy.rb b/bin/proxy.rb
index 49f89d79..f230200c 100755
--- a/bin/proxy.rb
+++ b/bin/proxy.rb
@@ -1,3 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
+
 require 'billy'
 Billy::Proxy.new.start(false)
diff --git a/lib/billy.rb b/lib/billy.rb
index 839829a8..a14b756c 100644
--- a/lib/billy.rb
+++ b/lib/billy.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'billy/version'
 require 'billy/config'
 require 'billy/handlers/handler'
@@ -18,11 +20,11 @@
 
 module Billy
   def self.proxy
-    @billy_proxy ||= (
+    @proxy ||= begin
       proxy = Billy::Proxy.new
       proxy.start
       proxy
-    )
+    end
   end
 
   def self.certificate_authority
@@ -33,13 +35,13 @@ def self.certificate_authority
   # the request beforehand and/or modify the actual response which is passed
   # back by this method. But you can also implement a custom proxy passing
   # method if you like to. This is just a shortcut.
-  def self.pass_request(params, headers, body, url, method)
-      handler = proxy.request_handler.handlers[:proxy]
-      response = handler.handle_request(method, url, headers, body)
-      {
-        code: response[:status],
-        body: response[:content],
-        headers: response[:headers]
-      }
+  def self.pass_request(_params, headers, body, url, method)
+    handler = proxy.request_handler.handlers[:proxy]
+    response = handler.handle_request(method, url, headers, body)
+    {
+      code: response[:status],
+      body: response[:content],
+      headers: response[:headers]
+    }
   end
 end
diff --git a/lib/billy/browsers/capybara.rb b/lib/billy/browsers/capybara.rb
index 66f16ead..8d099d80 100644
--- a/lib/billy/browsers/capybara.rb
+++ b/lib/billy/browsers/capybara.rb
@@ -1,89 +1,54 @@
+# frozen_string_literal: true
+
 require 'billy'
 
 module Billy
   module Browsers
     class Capybara
-
-      DRIVERS = {
-        poltergeist: 'capybara/poltergeist',
-        webkit: 'capybara/webkit',
-        selenium: 'selenium/webdriver',
-        apparition: 'capybara/apparition'
-      }
-
       def self.register_drivers
-        DRIVERS.each do |name, driver|
-          begin
-            require driver
-            send("register_#{name}_driver")
-          rescue LoadError
-          end
-        end
-      end
-
-      private
-
-      def self.register_poltergeist_driver
-        ::Capybara.register_driver :poltergeist_billy do |app|
-          options = {
-            phantomjs_options: [
-              '--ignore-ssl-errors=yes',
-              "--proxy=#{Billy.proxy.host}:#{Billy.proxy.port}"
-            ]
-          }
-          ::Capybara::Poltergeist::Driver.new(app, options)
-        end
-      end
-
-      def self.register_webkit_driver
-        ::Capybara.register_driver :webkit_billy do |app|
-          options = {
-            ignore_ssl_errors: true,
-            proxy: {host: Billy.proxy.host, port: Billy.proxy.port}
-          }
-          ::Capybara::Webkit::Driver.new(app, ::Capybara::Webkit::Configuration.to_hash.merge(options))
-        end
+        require 'selenium/webdriver'
+        register_selenium_driver
+      rescue LoadError
       end
 
       def self.register_selenium_driver
         ::Capybara.register_driver :selenium_billy do |app|
-          profile = Selenium::WebDriver::Firefox::Profile.new
-          profile.assume_untrusted_certificate_issuer = false
-          profile.proxy = Selenium::WebDriver::Proxy.new(
+          options = Selenium::WebDriver::Firefox::Options.new
+          options.proxy = Selenium::WebDriver::Proxy.new(
             http: "#{Billy.proxy.host}:#{Billy.proxy.port}",
-            ssl: "#{Billy.proxy.host}:#{Billy.proxy.port}")
-          ::Capybara::Selenium::Driver.new(app, profile: profile)
+            ssl: "#{Billy.proxy.host}:#{Billy.proxy.port}"
+          )
+          ::Capybara::Selenium::Driver.new(app, browser: :firefox, options: options)
         end
 
         ::Capybara.register_driver :selenium_chrome_billy do |app|
           options = Selenium::WebDriver::Chrome::Options.new
+          options.binary = ENV['CHROME_BIN'] if ENV['CHROME_BIN']
           options.add_argument("--proxy-server=#{Billy.proxy.host}:#{Billy.proxy.port}")
 
           ::Capybara::Selenium::Driver.new(
             app, browser: :chrome,
-            options: options
+                 options: options
           )
         end
-        
+
         ::Capybara.register_driver :selenium_chrome_headless_billy do |app|
-          options = Selenium::WebDriver::Chrome::Options.new(args: %w[headless disable-gpu no-sandbox
-                                                                      enable-features=NetworkService,NetworkServiceInProcess])
+          options = Selenium::WebDriver::Chrome::Options.new
+          options.binary = ENV['CHROME_BIN'] if ENV['CHROME_BIN']
+
+          options.add_argument('--headless=new')
+          options.add_argument('--no-sandbox')
+          options.add_argument('--disable-dev-shm-usage')
+          options.add_argument('--disable-gpu')
+
           options.add_argument("--proxy-server=#{Billy.proxy.host}:#{Billy.proxy.port}")
 
           ::Capybara::Selenium::Driver.new(
             app, browser: :chrome,
-            options: options
+                 options: options
           )
         end
       end
-
-      def self.register_apparition_driver
-        ::Capybara.register_driver :apparition_billy do |app|
-          ::Capybara::Apparition::Driver.new(app, ignore_https_errors: true).tap do |driver|
-            driver.set_proxy(Billy.proxy.host, Billy.proxy.port)
-          end
-        end
-      end
     end
   end
 end
diff --git a/lib/billy/browsers/watir.rb b/lib/billy/browsers/watir.rb
index 5ee51969..a4b7a89d 100644
--- a/lib/billy/browsers/watir.rb
+++ b/lib/billy/browsers/watir.rb
@@ -1,45 +1,39 @@
+# frozen_string_literal: true
+
 require 'billy'
 require 'watir'
 
 module Billy
   module Browsers
     class Watir < ::Watir::Browser
-
       def initialize(name, args = {})
         args = case name
-          when :chrome then configure_chrome(args)
-          when :phantomjs then configure_phantomjs(args)
-          when :firefox then configure_firefox(args)
-          else
-            raise NameError, "Invalid browser driver specified. (Expected: :chrome, :phantomjs, :firefox)"
-        end
+               when :chrome then configure_chrome(args)
+               when :firefox then configure_firefox(args)
+               else
+                 raise NameError, 'Invalid browser driver specified. (Expected: :chrome, :firefox)'
+               end
         super
       end
 
       private
 
       def configure_chrome(args)
-        args[:switches] ||= []
-        args[:switches] += %W[--proxy-server=#{Billy.proxy.host}:#{Billy.proxy.port}]
-        args
-      end
-
-      def configure_phantomjs(args)
-        args[:driver_opts] ||= {}
-        args[:driver_opts][:args] ||= []
-        args[:driver_opts][:args] += %W[--proxy=#{Billy.proxy.host}:#{Billy.proxy.port}]
+        options = args.delete(:options) || Selenium::WebDriver::Chrome::Options.new
+        options.add_argument("--proxy-server=#{Billy.proxy.host}:#{Billy.proxy.port}")
+        args[:options] = options
         args
       end
 
       def configure_firefox(args)
-        args[:profile] ||= Selenium::WebDriver::Firefox::Profile.new
-        args[:profile].proxy = Selenium::WebDriver::Proxy.new(
+        options = args.delete(:options) || Selenium::WebDriver::Firefox::Options.new
+        options.proxy = Selenium::WebDriver::Proxy.new(
           http: "#{Billy.proxy.host}:#{Billy.proxy.port}",
           ssl: "#{Billy.proxy.host}:#{Billy.proxy.port}"
         )
+        args[:options] = options
         args
       end
-
     end
   end
 end
diff --git a/lib/billy/cache.rb b/lib/billy/cache.rb
index 0d4b4263..4e8e1c0a 100644
--- a/lib/billy/cache.rb
+++ b/lib/billy/cache.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'resolv'
 require 'addressable/uri'
 require 'yaml'
@@ -18,7 +20,7 @@ def cached?(method, url, body, cache_scope)
       # Only log the key the first time it's looked up (in this method)
       key = key(method, url, body, cache_scope, true)
       cached = !@cache[key].nil? || persisted?(key)
-      purl = url.match(/.*staging\.hirefrederick.com\:443(.*)/)
+      purl = url.match(/.*staging\.hirefrederick.com:443(.*)/)
       if purl && cached
         puts "FOUND CACHE: #{scope} #{method} #{purl.captures[0]} #{key}"
       elsif purl
@@ -60,17 +62,17 @@ def store(key, _scope, method, url, request_headers, body, response_headers, sta
 
       @cache[key] = cached
 
-      if Billy.config.persist_cache
-        FileUtils.mkdir_p(Billy.config.cache_path) unless File.exist?(Billy.config.cache_path)
+      return unless Billy.config.persist_cache
+
+      FileUtils.mkdir_p(Billy.config.cache_path) unless File.exist?(Billy.config.cache_path)
 
-        begin
-          File.open(cache_file(key), 'w') do |f|
-            Billy.log(:info, "puffing-billy: Writing to cache: #{method} '#{url}'")
-            f.write(cached.to_yaml(Encoding: :Utf8))
-          end
-        rescue StandardError => e
-          Billy.log :error, "Error storing cache file: #{e.message}"
+      begin
+        File.open(cache_file(key), 'w') do |f|
+          Billy.log(:info, "puffing-billy: Writing to cache: #{method} '#{url}'")
+          f.write(cached.to_yaml(Encoding: :Utf8))
         end
+      rescue StandardError => e
+        Billy.log :error, "Error storing cache file: #{e.message}"
       end
     end
 
@@ -78,41 +80,38 @@ def reset
       @cache = {}
     end
 
-    def key(method, orig_url, body, cache_scope, log_key = false)
-      key_type = ''
-      if Billy.config.use_ignore_params
-        ignore_params = Billy.config.ignore_params.include?(format_url(orig_url, true))
-      else
-        ignore_params = !Billy.config.allow_params.include?(format_url(orig_url, true))
-      end
+    def key(method, orig_url, _body, cache_scope, log_key = false)
+      ignore_params = if Billy.config.use_ignore_params
+                        Billy.config.ignore_params.include?(format_url(orig_url, true))
+                      else
+                        !Billy.config.allow_params.include?(format_url(orig_url, true))
+                      end
       merge_cached_response_key = _merge_cached_response_key(orig_url)
       url = Addressable::URI.parse(format_url(orig_url, ignore_params))
       key = if merge_cached_response_key
-              key_type = '1'
-              method + '_' + Digest::SHA1.hexdigest(cache_scope.to_s + merge_cached_response_key)
+              "#{method}_#{Digest::SHA1.hexdigest(cache_scope.to_s + merge_cached_response_key)}"
             else
-              key_type = '2'
-              method + '_' + url.host + '_' + Digest::SHA1.hexdigest(cache_scope.to_s + url.to_s)
+              "#{method}_#{url.host}_#{Digest::SHA1.hexdigest(cache_scope.to_s + url.to_s)}"
             end
       body_msg = ''
 
-      #if Billy.config.cache_request_body_methods.include?(method) && !ignore_params && !merge_cached_response_key
-        #body_formatted = JSONUtils.json?(body.to_s) ? JSONUtils.sort_json(body.to_s) : body.to_s
-        #body_msg = " with body '#{body_formatted}'"
-        #key_type = 3
-        #key += '_' + Digest::SHA1.hexdigest(body_formatted)
-      #end
+      # if Billy.config.cache_request_body_methods.include?(method) && !ignore_params && !merge_cached_response_key
+      # body_formatted = JSONUtils.json?(body.to_s) ? JSONUtils.sort_json(body.to_s) : body.to_s
+      # body_msg = " with body '#{body_formatted}'"
+      # key_type = 3
+      # key += '_' + Digest::SHA1.hexdigest(body_formatted)
+      # end
 
       Billy.log(:info, "puffing-billy: CACHE KEY for '#{orig_url}#{body_msg}' is '#{key}'") if log_key
-      #purl = orig_url.match(/.*staging\.hirefrederick.com\:443(.*)/)
-      #puts "CREATING KEY TYPE: #{key_type} #{scope} #{method} #{purl.captures[0]} #{key}" if purl
+      # purl = orig_url.match(/.*staging\.hirefrederick.com\:443(.*)/)
+      # puts "CREATING KEY TYPE: #{key_type} #{scope} #{method} #{purl.captures[0]} #{key}" if purl
       key
     end
 
     def format_url(url, ignore_params = false, dynamic_jsonp = Billy.config.dynamic_jsonp)
       url = Addressable::URI.parse(url)
       port_to_include = Billy.config.ignore_cache_port ? '' : ":#{url.port}"
-      formatted_url = url.scheme + '://' + url.host + port_to_include + url.path
+      formatted_url = "#{url.scheme}://#{url.host}#{port_to_include}#{url.path}"
 
       return formatted_url if ignore_params
 
@@ -128,7 +127,7 @@ def format_url(url, ignore_params = false, dynamic_jsonp = Billy.config.dynamic_
         formatted_url += "?#{query_string}"
       end
 
-      formatted_url += '#' + url.fragment if url.fragment
+      formatted_url += "##{url.fragment}" if url.fragment
 
       formatted_url
     end
@@ -136,9 +135,7 @@ def format_url(url, ignore_params = false, dynamic_jsonp = Billy.config.dynamic_
     def cache_file(key)
       file = File.join(Billy.config.cache_path, "#{key}.yml")
 
-      if File.symlink? file
-        file = File.readlink file
-      end
+      file = File.readlink file if File.symlink? file
 
       file
     end
@@ -148,7 +145,8 @@ def scope_to(new_scope = nil)
     end
 
     def with_scope(use_scope = nil, &block)
-      fail ArgumentError, 'Expected a block but none was received.' if block.nil?
+      raise ArgumentError, 'Expected a block but none was received.' if block.nil?
+
       original_scope = scope
       scope_to use_scope
       block.call
diff --git a/lib/billy/capybara/cucumber.rb b/lib/billy/capybara/cucumber.rb
index e485dca8..53d4d39e 100644
--- a/lib/billy/capybara/cucumber.rb
+++ b/lib/billy/capybara/cucumber.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'capybara/cucumber'
 require 'billy/browsers/capybara'
 require 'billy/init/cucumber'
diff --git a/lib/billy/capybara/rspec.rb b/lib/billy/capybara/rspec.rb
index 628f24e8..597e3fed 100644
--- a/lib/billy/capybara/rspec.rb
+++ b/lib/billy/capybara/rspec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'capybara/rspec'
 require 'billy/browsers/capybara'
 require 'billy/init/rspec'
diff --git a/lib/billy/config.rb b/lib/billy/config.rb
index cc7994ec..02d908af 100644
--- a/lib/billy/config.rb
+++ b/lib/billy/config.rb
@@ -1,9 +1,11 @@
+# frozen_string_literal: true
+
 require 'logger'
 require 'tmpdir'
 
 module Billy
   class Config
-    DEFAULT_WHITELIST = ['127.0.0.1', 'localhost']
+    DEFAULT_WHITELIST = ['127.0.0.1', 'localhost'].freeze
     RANDOM_AVAILABLE_PORT = 0 # https://github.com/eventmachine/eventmachine/wiki/FAQ#wiki-can-i-start-a-server-on-a-random-available-port
 
     attr_accessor :logger, :cache, :cache_request_headers, :whitelist, :path_blacklist, :ignore_params, :allow_params,
@@ -15,7 +17,7 @@ class Config
                   :refresh_persisted_cache
 
     def initialize
-      @logger = defined?(Rails) ? Rails.logger : Logger.new(STDOUT)
+      @logger = defined?(Rails) ? Rails.logger : Logger.new($stdout)
       reset
     end
 
@@ -37,7 +39,7 @@ def reset
       @non_whitelisted_requests_disabled = false
       @cache_path = File.join(Dir.tmpdir, 'puffing-billy')
       @certs_path = File.join(Dir.tmpdir, 'puffing-billy', 'certs')
-      @proxy_host = 'localhost'
+      @proxy_host = '127.0.0.1'
       @proxy_port = RANDOM_AVAILABLE_PORT
       @proxied_request_inactivity_timeout = 10 # defaults from https://github.com/igrigorik/em-http-request/wiki/Redirects-and-Timeouts
       @proxied_request_connect_timeout = 5
@@ -61,12 +63,10 @@ def self.configure
   end
 
   def self.log(*args)
-    unless config.logger.nil?
-      config.logger.send(*args)
-    end
-  end
+    return if config.logger.nil?
 
-  private
+    config.logger.send(*args)
+  end
 
   def self.config
     @config ||= Config.new
diff --git a/lib/billy/cucumber.rb b/lib/billy/cucumber.rb
index 6d84a580..91e00872 100644
--- a/lib/billy/cucumber.rb
+++ b/lib/billy/cucumber.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Deprecated
 require 'billy/capybara/cucumber'
 
diff --git a/lib/billy/handlers/cache_handler.rb b/lib/billy/handlers/cache_handler.rb
index 08a384ab..d459ff35 100644
--- a/lib/billy/handlers/cache_handler.rb
+++ b/lib/billy/handlers/cache_handler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'billy/handlers/handler'
 require 'addressable/uri'
 require 'cgi'
@@ -17,31 +19,27 @@ def initialize
 
     def handle_request(method, url, headers, body, cache_scope)
       method = method.downcase
-      if handles_request?(method, url, headers, body, cache_scope)
-        if (response = cache.fetch(method, url, body, cache_scope))
-          Billy.log(:info, "puffing-billy: CACHE #{method} for '#{url}'")
+      if handles_request?(method, url, headers, body,
+                          cache_scope) && (response = cache.fetch(method, url, body, cache_scope))
+        Billy.log(:info, "puffing-billy: CACHE #{method} for '#{url}'")
 
-          if Billy.config.dynamic_jsonp
-            replace_response_callback(response, url)
-          end
+        replace_response_callback(response, url) if Billy.config.dynamic_jsonp
 
-          if Billy.config.after_cache_handles_request
-            request = { method: method, url: url, headers: headers, body: body }
-            Billy.config.after_cache_handles_request.call(request, response)
-          end
+        if Billy.config.after_cache_handles_request
+          request = { method: method, url: url, headers: headers, body: body }
+          Billy.config.after_cache_handles_request.call(request, response)
+        end
 
-          if Billy.config.cache_simulates_network_delays
-            Kernel.sleep(Billy.config.cache_simulates_network_delay_time)
-          end
+        Kernel.sleep(Billy.config.cache_simulates_network_delay_time) if Billy.config.cache_simulates_network_delays
 
-          return response
-        end
+        return response
       end
       nil
     end
 
     def handles_request?(method, url, _headers, body, cache_scope)
       return false if Billy.config.refresh_persisted_cache
+
       cached?(method, url, body, cache_scope)
     end
 
@@ -49,13 +47,13 @@ def handles_request?(method, url, _headers, body, cache_scope)
 
     def replace_response_callback(response, url)
       request_uri = Addressable::URI.parse(url)
-      if request_uri.query
-        params = CGI.parse(request_uri.query)
-        callback_name = Billy.config.dynamic_jsonp_callback_name
-        if params[callback_name].any? && response[:content].match(/\w+\(/)
-          response[:content].sub!(/\w+\(/, params[callback_name].first + '(')
-        end
-      end
+      return unless request_uri.query
+
+      params = CGI.parse(request_uri.query)
+      callback_name = Billy.config.dynamic_jsonp_callback_name
+      return unless params[callback_name].any? && response[:content].match(/\w+\(/)
+
+      response[:content] = response[:content].sub(/\w+\(/, "#{params[callback_name].first}(")
     end
   end
 end
diff --git a/lib/billy/handlers/handler.rb b/lib/billy/handlers/handler.rb
index 16641d02..ed6858ef 100644
--- a/lib/billy/handlers/handler.rb
+++ b/lib/billy/handlers/handler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Billy
   module Handler
     ##
diff --git a/lib/billy/handlers/proxy_handler.rb b/lib/billy/handlers/proxy_handler.rb
index dc56fff9..c47b3c72 100644
--- a/lib/billy/handlers/proxy_handler.rb
+++ b/lib/billy/handlers/proxy_handler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'billy/handlers/handler'
 require 'addressable/uri'
 require 'eventmachine'
@@ -11,31 +13,30 @@ class ProxyHandler
 
     def_delegators :request_log, :requests
 
-    def handles_request?(_method, url, _headers, _body, cache_scope)
-      purl = url.match(/.*staging\.hirefrederick.com\:443/)
+    def handles_request?(_method, url, _headers, _body, _cache_scope)
+      purl = url.match(/.*staging\.hirefrederick.com:443/)
       return false if !Billy.config.refresh_persisted_cache && purl
+
       !disabled_request?(url)
     end
 
     def handle_request(method, url, headers, body, cache_scope)
       if handles_request?(method, url, headers, body, cache_scope)
         opts = { inactivity_timeout: Billy.config.proxied_request_inactivity_timeout,
-                 connect_timeout:    Billy.config.proxied_request_connect_timeout }
+                 connect_timeout: Billy.config.proxied_request_connect_timeout }
 
         if Billy.config.proxied_request_host && !bypass_internal_proxy?(url)
           opts.merge!({ proxy: { host: Billy.config.proxied_request_host,
-                                 port: Billy.config.proxied_request_port }} )
+                                 port: Billy.config.proxied_request_port } })
         end
 
-        #cache_scope = Billy::Cache.instance.scope
+        # cache_scope = Billy::Cache.instance.scope
         cache_key = Billy::Cache.instance.key(method.downcase, url, body, cache_scope)
 
         req = EventMachine::HttpRequest.new(url, opts)
         req = req.send(method.downcase, build_request_options(url, headers, body))
 
-        if req.error
-          return { error: "Request to #{url} failed with error: #{req.error}" }
-        end
+        return { error: "Request to #{url} failed with error: #{req.error}" } if req.error
 
         if req.response
           response = process_response(req, cache_key)
@@ -43,12 +44,13 @@ def handle_request(method, url, headers, body, cache_scope)
           unless allowed_response_code?(response[:status])
             if Billy.config.non_successful_error_level == :error
               return { error: "#{method} Request failed due to response status #{response[:status]} for '#{url}' which was not allowed." }
-            else
-              Billy.log(:warn, "puffing-billy: Received response status code #{response[:status]} for '#{url}'")
             end
+
+            Billy.log(:warn, "puffing-billy: Received response status code #{response[:status]} for '#{url}'")
+
           end
 
-          purl = url.match(/.*staging\.hirefrederick.com\:443(.*)/)
+          purl = url.match(/.*staging\.hirefrederick.com:443(.*)/)
           if cacheable?(url, response[:headers], response[:status])
             puts "CACHING: #{cache_scope} #{method} #{purl.captures[0]} #{cache_key}" if purl
 
@@ -64,8 +66,11 @@ def handle_request(method, url, headers, body, cache_scope)
               response[:content]
             )
           else
-            Billy.log(:info, "puffing-billy: NOT CACHEABLE: Status: #{response[:status]} #{cache_scope} #{method} #{url} #{cache_key}")
-            puts "NOT CACHABLE: Status: #{response[:status]} #{cache_scope} #{method} #{purl.captures[0]} #{cache_key}" if purl
+            Billy.log(:info,
+                      "puffing-billy: NOT CACHEABLE: Status: #{response[:status]} #{cache_scope} #{method} #{url} #{cache_key}")
+            if purl
+              puts "NOT CACHABLE: Status: #{response[:status]} #{cache_scope} #{method} #{purl.captures[0]} #{cache_key}"
+            end
           end
 
           Billy.log(:info, "puffing-billy: PROXY #{method} succeeded for #{url}")
@@ -75,14 +80,14 @@ def handle_request(method, url, headers, body, cache_scope)
       nil
     end
 
-  private
+    private
 
     def build_request_options(url, headers, body)
-      headers = Hash[headers.map { |k, v| [k.downcase, v] }]
+      headers = headers.transform_keys(&:downcase)
       headers['accept-encoding'] = ''
 
       uri = Addressable::URI.parse(url)
-      headers.merge!({'authorization' => [uri.user, uri.password]}) if uri.userinfo
+      headers.merge!({ 'authorization' => [uri.user, uri.password] }) if uri.userinfo
 
       req_opts = {
         redirects: 0,
@@ -122,12 +127,12 @@ def cacheable?(url, _headers, status)
       # Don't save a cache file if the cache is off or we're not refreshing the cache
       return false if !Billy.config.cache || !Billy.config.refresh_persisted_cache
 
-      #orig_url = url
+      # orig_url = url
       url = Addressable::URI.parse(url)
       # Cache the responses if they aren't whitelisted host[:port]s but always cache blacklisted paths on any hosts
-      #if orig_url.match(/background/)
-        #byebug
-      #end
+      # if orig_url.match(/background/)
+      # byebug
+      # end
       cacheable_status?(status) && (!whitelisted_url?(url) || blacklisted_path?(url.path))
     end
 
diff --git a/lib/billy/handlers/request_handler.rb b/lib/billy/handlers/request_handler.rb
index c5c51a4b..645363f2 100644
--- a/lib/billy/handlers/request_handler.rb
+++ b/lib/billy/handlers/request_handler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'forwardable'
 
 module Billy
@@ -15,12 +17,12 @@ def handlers
     end
 
     def handle_request(method, url, headers, body)
-      previous_duplicate_requests = request_log.requests.select {|x| x[:method] == method && x[:url] == url }
+      previous_duplicate_requests = request_log.requests.select { |x| x[:method] == method && x[:url] == url }
       cache_scope = previous_duplicate_requests.length
       request = request_log.record(method, url, headers, body, cache_scope)
 
       # Process the handlers by order of importance
-      [:stubs, :cache, :proxy].each do |key|
+      %i[stubs cache proxy].each do |key|
         if (response = handlers[key].handle_request(method, url, headers, body, cache_scope))
           @request_log.complete(request, key, response[:cache_key])
           return response
@@ -28,17 +30,17 @@ def handle_request(method, url, headers, body)
       end
 
       body_msg = Billy.config.cache_request_body_methods.include?(method) ? " with body '#{body}'" : ''
-      request_log.complete(request, :error)
+      request_log.complete(request, :error, nil)
       { error: "Connection to #{url}#{body_msg} not cached and new http connections are disabled" }
-    rescue => error
-      { error: error.message }
+    rescue StandardError => e
+      { error: e.message }
     end
 
-    #def handles_request?(method, url, headers, body)
-      #[:stubs, :cache, :proxy].any? do |key|
-        #handlers[key].handles_request?(method, url, headers, body)
-      #end
-    #end
+    # def handles_request?(method, url, headers, body)
+    # [:stubs, :cache, :proxy].any? do |key|
+    # handlers[key].handles_request?(method, url, headers, body)
+    # end
+    # end
 
     def request_log
       @request_log ||= RequestLog.new
diff --git a/lib/billy/handlers/request_log.rb b/lib/billy/handlers/request_log.rb
index a925a874..2c7c54ec 100644
--- a/lib/billy/handlers/request_log.rb
+++ b/lib/billy/handlers/request_log.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Billy
   class RequestLog
     attr_reader :requests
@@ -12,7 +14,7 @@ def reset
 
     def record(method, url, headers, body, cache_scope)
       Billy.log(:info, "puffing-billy: REQUEST LOG: #{method} #{url}")
-      purl = url.match(/.*staging\.hirefrederick.com\:443(.*)/)
+      purl = url.match(/.*staging\.hirefrederick.com:443(.*)/)
       puts "REQUEST LOG: #{cache_scope} #{method} #{purl.captures[0]}" if purl
       return unless Billy.config.record_requests
 
diff --git a/lib/billy/handlers/stub_handler.rb b/lib/billy/handlers/stub_handler.rb
index 385185f0..5ce8b716 100644
--- a/lib/billy/handlers/stub_handler.rb
+++ b/lib/billy/handlers/stub_handler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'billy/handlers/handler'
 require 'addressable/uri'
 
@@ -6,21 +8,19 @@ class StubHandler
     include Handler
 
     def handle_request(method, url, headers, body, cache_scope)
-      if handles_request?(method, url, headers, body, cache_scope)
-        if (stub = find_stub(method, url))
-          query_string = Addressable::URI.parse(url).query || ''
-          params = CGI.parse(query_string)
-          stub.call(method, url, params, headers, body).tap do |response|
-            Billy.log(:info, "puffing-billy: STUB #{method} for '#{url}'")
-            return { status: response[0], headers: response[1], content: response[2] }
-          end
+      if handles_request?(method, url, headers, body, cache_scope) && (stub = find_stub(method, url))
+        query_string = Addressable::URI.parse(url).query || ''
+        params = CGI.parse(query_string)
+        stub.call(method, url, params, headers, body).tap do |response|
+          Billy.log(:info, "puffing-billy: STUB #{method} for '#{url}'")
+          return { status: response[0], headers: response[1], content: response[2] }
         end
       end
 
       nil
     end
 
-    def handles_request?(method, url, _headers, _body, cache_scope)
+    def handles_request?(method, url, _headers, _body, _cache_scope)
       !find_stub(method, url).nil?
     end
 
diff --git a/lib/billy/init/cucumber.rb b/lib/billy/init/cucumber.rb
index d456e54a..aec0981f 100644
--- a/lib/billy/init/cucumber.rb
+++ b/lib/billy/init/cucumber.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'cucumber'
 
 module Billy
diff --git a/lib/billy/init/rspec.rb b/lib/billy/init/rspec.rb
index 0a6e7266..e45fd7a4 100644
--- a/lib/billy/init/rspec.rb
+++ b/lib/billy/init/rspec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Billy
   module RspecHelper
     def proxy
diff --git a/lib/billy/json_utils.rb b/lib/billy/json_utils.rb
index 50bd7fff..54340066 100644
--- a/lib/billy/json_utils.rb
+++ b/lib/billy/json_utils.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'json'
 
 module Billy
@@ -12,10 +14,10 @@ def self.json?(value)
     #   data structure while preserving the order of arrays.
     def self.sort_hash_keys(data)
       return data unless data.is_a?(Hash) || data.is_a?(Array)
+
       if data.is_a? Hash
-        data.keys.sort.reduce({}) do |seed, key|
+        data.keys.sort.each_with_object({}) do |key, seed|
           seed[key] = sort_hash_keys(data[key])
-          seed
         end
       else
         data.map do |element|
diff --git a/lib/billy/proxy.rb b/lib/billy/proxy.rb
index a726c3cc..256a9ef9 100644
--- a/lib/billy/proxy.rb
+++ b/lib/billy/proxy.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'cgi'
 require 'eventmachine'
 require 'timeout'
@@ -5,9 +7,10 @@
 module Billy
   class Proxy
     extend Forwardable
-    attr_reader :request_handler
+    attr_reader :request_handler, :port
 
-    def_delegators :request_handler, :stub, :stubs, :unstub, :reset, :reset_cache, :restore_cache, :requests, :handle_request
+    def_delegators :request_handler, :stub, :stubs, :unstub, :reset, :reset_cache, :restore_cache, :requests,
+                   :handle_request
 
     def initialize
       @request_handler = Billy::RequestHandler.new
@@ -17,7 +20,7 @@ def initialize
     def start(threaded = true)
       if threaded
         Thread.new { main_loop }
-        sleep(0.01) while (not defined?(@signature)) || @signature.nil?
+        sleep(0.01) while !defined?(@port) || @port.nil?
       else
         main_loop
       end
@@ -39,10 +42,6 @@ def host
       Billy.config.proxy_host
     end
 
-    def port
-      Socket.unpack_sockaddr_in(EM.get_sockname(@signature)).first
-    end
-
     def cache
       Billy::Cache.instance
     end
@@ -50,7 +49,7 @@ def cache
     protected
 
     def wait_for_server_shutdown!(server_port)
-      Timeout::timeout(60) do
+      Timeout.timeout(60) do
         sleep(0.01) while port_in_use? server_port
       end
     rescue Timeout::Error
@@ -81,6 +80,8 @@ def main_loop
           end
         end
 
+        @port = Socket.unpack_sockaddr_in(EM.get_sockname(@signature)).first
+
         Billy.log(:info, "puffing-billy: Proxy listening on #{url}")
       end
     end
diff --git a/lib/billy/proxy_connection.rb b/lib/billy/proxy_connection.rb
index 3f44c7d3..aa0a9219 100644
--- a/lib/billy/proxy_connection.rb
+++ b/lib/billy/proxy_connection.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'addressable/uri'
 require 'eventmachine'
 require 'http/parser'
@@ -9,8 +11,7 @@ module Billy
   class ProxyConnection < EventMachine::Connection
     include EventMachine::Deferrable
 
-    attr_accessor :handler
-    attr_accessor :cache
+    attr_accessor :handler, :cache
 
     def post_init
       @parser = Http::Parser.new(self)
@@ -22,7 +23,7 @@ def receive_data(data)
 
     def on_message_begin
       @headers = nil
-      @body = ''
+      @body = String.new
     end
 
     def on_headers_complete(headers)
@@ -61,7 +62,7 @@ def handle_request
         handler.handle_request(@parser.http_method, @url, @headers, @body).tap do |response|
           if response.key?(:error)
             close_connection
-            fail "puffing-billy: #{response[:error]}"
+            raise "puffing-billy: #{response[:error]}"
           else
             send_response(response)
           end
@@ -74,13 +75,13 @@ def handle_request
     def prepare_response_headers_for_evma_httpserver(headers)
       # Remove the headers below because they will be added later by evma_httpserver (EventMachine::DelegatedHttpResponse).
       # See https://github.com/eventmachine/evma_httpserver/blob/master/lib/evma_httpserver/response.rb
-      headers_to_remove = [
-        'transfer-encoding',
-        'content-length',
-        'content-encoding'
+      headers_to_remove = %w[
+        transfer-encoding
+        content-length
+        content-encoding
       ]
 
-      headers.delete_if {|key, value| headers_to_remove.include?(key.downcase) }
+      headers.delete_if { |key, _value| headers_to_remove.include?(key.downcase) }
     end
 
     def send_response(response)
diff --git a/lib/billy/proxy_request_stub.rb b/lib/billy/proxy_request_stub.rb
index 5d1a4196..5ef79390 100644
--- a/lib/billy/proxy_request_stub.rb
+++ b/lib/billy/proxy_request_stub.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'multi_json'
 
 module Billy
@@ -20,11 +22,11 @@ def and_return(response)
     def call(method, url, params, headers, body)
       push_request(method, url, params, headers, body)
 
-      if @response.respond_to?(:call)
-        res = @response.call(params, headers, body, url, method)
-      else
-        res = @response
-      end
+      res = if @response.respond_to?(:call)
+              @response.call(params, headers, body, url, method)
+            else
+              @response
+            end
 
       code = res[:code] || 200
 
@@ -36,13 +38,13 @@ def call(method, url, params, headers, body)
         body = MultiJson.dump(res[:json])
       elsif res[:jsonp]
         headers = { 'Content-Type' => 'application/javascript' }.merge(headers)
-        if res[:callback]
-          callback = res[:callback]
-        elsif res[:callback_param]
-          callback = params[res[:callback_param]][0]
-        else
-          callback = params['callback'][0]
-        end
+        callback = if res[:callback]
+                     res[:callback]
+                   elsif res[:callback_param]
+                     params[res[:callback_param]][0]
+                   else
+                     params['callback'][0]
+                   end
         body = "#{callback}(#{MultiJson.dump(res[:jsonp])})"
       elsif res[:text]
         headers = { 'Content-Type' => 'text/plain' }.merge(headers)
@@ -62,12 +64,12 @@ def has_requests?
     end
 
     def matches?(method, url)
-      if @method == 'ALL' || method == @method
-        if @url.is_a?(Regexp)
-          url.match(@url)
-        else
-          Billy.config.strip_query_params ? (url.split('?')[0] == @url) : (url == @url)
-        end
+      return unless @method == 'ALL' || method == @method
+
+      if @url.is_a?(Regexp)
+        url.match(@url)
+      else
+        Billy.config.strip_query_params ? (url.split('?')[0] == @url) : (url == @url)
       end
     end
 
@@ -76,15 +78,15 @@ def matches?(method, url)
     attr_writer :requests
 
     def push_request(method, url, params, headers, body)
-      if Billy.config.record_stub_requests
-        @requests.push({
-          method: method,
-          url: url,
-          params: params,
-          headers: headers,
-          body: body
-        })
-      end
+      return unless Billy.config.record_stub_requests
+
+      @requests.push({
+                       method: method,
+                       url: url,
+                       params: params,
+                       headers: headers,
+                       body: body
+                     })
     end
   end
 end
diff --git a/lib/billy/railtie.rb b/lib/billy/railtie.rb
index 246e7a77..63ce7378 100644
--- a/lib/billy/railtie.rb
+++ b/lib/billy/railtie.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Billy
   class Railtie < Rails::Railtie
     railtie_name 'billy'
diff --git a/lib/billy/rspec.rb b/lib/billy/rspec.rb
index 6f33b719..a19a9550 100644
--- a/lib/billy/rspec.rb
+++ b/lib/billy/rspec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Deprecated
 require 'billy/capybara/rspec'
 
diff --git a/lib/billy/ssl/authority.rb b/lib/billy/ssl/authority.rb
index 8fe798be..a1712cb2 100644
--- a/lib/billy/ssl/authority.rb
+++ b/lib/billy/ssl/authority.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 # frozen_string_literal: true
 
 require 'openssl'
@@ -69,7 +68,7 @@ def generate
       cert = OpenSSL::X509::Certificate.new
       configure(cert)
       add_extensions(cert)
-      cert.sign(key, OpenSSL::Digest::SHA256.new)
+      cert.sign(key, OpenSSL::Digest.new('SHA256'))
     end
 
     # Setup all relevant properties of the given certificate to produce
diff --git a/lib/billy/ssl/certificate.rb b/lib/billy/ssl/certificate.rb
index 734fd876..01c701ad 100644
--- a/lib/billy/ssl/certificate.rb
+++ b/lib/billy/ssl/certificate.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 # frozen_string_literal: true
 
 require 'openssl'
@@ -62,7 +61,7 @@ def generate
       cert = OpenSSL::X509::Certificate.new
       configure(cert)
       add_extensions(cert)
-      cert.sign(Billy.certificate_authority.key, OpenSSL::Digest::SHA256.new)
+      cert.sign(Billy.certificate_authority.key, OpenSSL::Digest.new('SHA256'))
     end
 
     # Generate a new certificate signing request (CSR) which will be picked
@@ -71,7 +70,7 @@ def signing_request
       req = OpenSSL::X509::Request.new
       req.public_key = key.public_key
       req.subject = OpenSSL::X509::Name.new([['CN', domain]])
-      req.sign(key, OpenSSL::Digest::SHA256.new)
+      req.sign(key, OpenSSL::Digest.new('SHA256'))
     end
 
     # Setup all relevant properties of the given certificate to produce
diff --git a/lib/billy/ssl/certificate_chain.rb b/lib/billy/ssl/certificate_chain.rb
index 9176af41..801b1f02 100644
--- a/lib/billy/ssl/certificate_chain.rb
+++ b/lib/billy/ssl/certificate_chain.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 # frozen_string_literal: true
 
 require 'fileutils'
@@ -34,7 +33,7 @@ def initialize(domain, *certs)
     # produce a temporary file which will be remove after the current process
     # terminates.
     def file
-      contents = certificates.map { |cert| cert.to_pem }.join
+      contents = certificates.map(&:to_pem).join
       write_file("chain-#{domain}.pem", contents)
     end
   end
diff --git a/lib/billy/ssl/certificate_helpers.rb b/lib/billy/ssl/certificate_helpers.rb
index 8330d64d..d3dd80de 100644
--- a/lib/billy/ssl/certificate_helpers.rb
+++ b/lib/billy/ssl/certificate_helpers.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 # frozen_string_literal: true
 
 require 'openssl'
@@ -7,7 +6,6 @@
 module Billy
   # A set of common certificate helper methods.
   module CertificateHelpers
-
     # Give back the date from now plus given days.
     def days_from_now(days)
       Time.now + (days * 24 * 60 * 60)
diff --git a/lib/billy/version.rb b/lib/billy/version.rb
index 4a180a91..98173f0d 100644
--- a/lib/billy/version.rb
+++ b/lib/billy/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Billy
-  VERSION = '2.1.1'
+  VERSION = '3.0.0'
 end
diff --git a/lib/billy/watir/cucumber.rb b/lib/billy/watir/cucumber.rb
index 1af19e2e..c0cc898a 100644
--- a/lib/billy/watir/cucumber.rb
+++ b/lib/billy/watir/cucumber.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 require 'billy/browsers/watir'
 require 'billy/init/cucumber'
diff --git a/lib/billy/watir/rspec.rb b/lib/billy/watir/rspec.rb
index dd1c6ffc..4b898dc4 100644
--- a/lib/billy/watir/rspec.rb
+++ b/lib/billy/watir/rspec.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 require 'billy/browsers/watir'
 require 'billy/init/rspec'
diff --git a/lib/puffing-billy.rb b/lib/puffing-billy.rb
index bf02ebe8..6b128aa7 100644
--- a/lib/puffing-billy.rb
+++ b/lib/puffing-billy.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 require 'billy'
 PuffingBilly ||= Billy
diff --git a/lib/puffing-billy/rspec.rb b/lib/puffing-billy/rspec.rb
index fce688a1..2776799a 100644
--- a/lib/puffing-billy/rspec.rb
+++ b/lib/puffing-billy/rspec.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 require 'billy/rspec'
 PuffingBilly ||= Billy
diff --git a/lib/tasks/billy.rake b/lib/tasks/billy.rake
index 31b4b648..ca3376d1 100644
--- a/lib/tasks/billy.rake
+++ b/lib/tasks/billy.rake
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'addressable/uri'
 
 namespace :cache do
@@ -12,8 +14,9 @@ namespace :cache do
 
   desc 'Print out specific cache file information'
   task :print_details, :sha do |_t, args|
-    fail "Missing sha; usage: rake cache:print_details['<sha>']" unless args[:sha]
-    cache_array = load_cache(Billy.config.cache_path, '*' + args[:sha] + '*.yml')
+    raise "Missing sha; usage: rake cache:print_details['<sha>']" unless args[:sha]
+
+    cache_array = load_cache(Billy.config.cache_path, "*#{args[:sha]}*.yml")
 
     sort_cache(cache_array).each do |cache|
       print_cache_details(cache)
@@ -22,7 +25,8 @@ namespace :cache do
 
   desc 'Find specific cache files by URL'
   task :find_by_url, :api_path do |_t, args|
-    fail "Missing api path; usage: rake cache:find_by_url['<api_path>']" unless args[:api_path]
+    raise "Missing api path; usage: rake cache:find_by_url['<api_path>']" unless args[:api_path]
+
     cache_array = load_cache
     filtered_cache_array = cache_array.select { |f| f[:url_path].include?(args[:api_path]) }
 
@@ -33,9 +37,10 @@ namespace :cache do
 
   desc 'Find specific cache files by scope'
   task :find_by_scope, :scope do |_t, args|
-    fail "Missing scope; usage: rake cache:find_by_scope['<scope>']" unless args[:scope]
+    raise "Missing scope; usage: rake cache:find_by_scope['<scope>']" unless args[:scope]
+
     cache_array = load_cache
-    filtered_cache_array = cache_array.select { |f| f[:scope] && f[:scope].include?(args[:scope]) }
+    filtered_cache_array = cache_array.select { |f| f[:scope]&.include?(args[:scope]) }
 
     sort_cache(filtered_cache_array).each do |cache|
       print_cache_details(cache)
@@ -45,7 +50,7 @@ namespace :cache do
   desc 'Find cache files with non-successful status codes'
   task :find_non_successful do
     cache_array = load_cache
-    filtered_cache_array = cache_array.select { |f| !(200..299).include?(f[:status]) }
+    filtered_cache_array = cache_array.reject { |f| (200..299).include?(f[:status]) }
 
     sort_cache(filtered_cache_array).each do |cache|
       print_cache_details(cache)
@@ -59,8 +64,8 @@ namespace :cache do
     Dir.glob(cache_path + file_pattern) do |filename|
       data = load_cache_file(filename)
       url = Addressable::URI.parse(data[:url])
-      data[:url_path] = "#{url.path}#{url.query ? '?' + url.query : ''}#{url.fragment ? '#' + url.fragment : ''}"
-      data[:filename] = filename.gsub(Rails.root.to_s + '/', '')
+      data[:url_path] = "#{url.path}#{url.query ? "?#{url.query}" : ''}#{url.fragment ? "##{url.fragment}" : ''}"
+      data[:filename] = filename.gsub("#{Rails.root}/", '')
       cache_array << data
     end
     cache_array
diff --git a/puffing-billy.gemspec b/puffing-billy.gemspec
index 3eb196d0..29354ee9 100644
--- a/puffing-billy.gemspec
+++ b/puffing-billy.gemspec
@@ -1,5 +1,6 @@
-# -*- encoding: utf-8 -*-
-require File.expand_path('../lib/billy/version', __FILE__)
+# frozen_string_literal: true
+
+require File.expand_path('lib/billy/version', __dir__)
 
 Gem::Specification.new do |gem|
   gem.authors       = ['Olly Smith']
@@ -7,6 +8,7 @@ Gem::Specification.new do |gem|
   gem.description   = 'A stubbing proxy server for ruby. Connect it to your browser in integration tests to fake interactions with remote HTTP(S) servers.'
   gem.summary       = 'Easy request stubs for browser tests.'
   gem.homepage      = 'https://github.com/oesmith/puffing-billy'
+  gem.required_ruby_version = '>= 3.3.10'
 
   gem.files         = `git ls-files`.split($OUTPUT_RECORD_SEPARATOR)
   gem.executables   = gem.files.grep(%r{^bin/}).map { |f| File.basename(f) }
@@ -15,26 +17,27 @@ Gem::Specification.new do |gem|
   gem.require_paths = ['lib']
   gem.version       = Billy::VERSION
 
-  gem.add_development_dependency 'rspec'
-  gem.add_development_dependency 'thin'
-  gem.add_development_dependency 'faraday'
-  gem.add_development_dependency 'poltergeist'
-  gem.add_development_dependency 'apparition'
-  # selenium-webdriver 3.8 drops support for PhantomJS
-  gem.add_development_dependency 'selenium-webdriver', '<= 3.7.0'
-  gem.add_development_dependency 'capybara'
-  gem.add_development_dependency 'capybara-webkit', '~> 1.0'
-  gem.add_development_dependency 'rack'
-  gem.add_development_dependency 'guard'
-  gem.add_development_dependency 'rb-inotify'
-  gem.add_development_dependency 'pry'
-  gem.add_development_dependency 'cucumber'
-  gem.add_development_dependency 'watir', '~> 6.10.0'
   gem.add_runtime_dependency 'addressable', '~> 2.5'
-  gem.add_runtime_dependency 'eventmachine', '~> 1.2'
-  gem.add_runtime_dependency 'em-synchrony'
   gem.add_runtime_dependency 'em-http-request', '~> 1.1', '>= 1.1.0'
+  gem.add_runtime_dependency 'em-synchrony'
+  gem.add_runtime_dependency 'eventmachine', '~> 1.2'
   gem.add_runtime_dependency 'eventmachine_httpserver'
-  gem.add_runtime_dependency 'http_parser.rb', '~> 0.6.0'
+  gem.add_runtime_dependency 'http_parser.rb', '~> 0.8.0'
   gem.add_runtime_dependency 'multi_json'
+
+  gem.add_development_dependency 'capybara'
+  gem.add_development_dependency 'cucumber'
+  gem.add_development_dependency 'faraday'
+  gem.add_development_dependency 'guard'
+  gem.add_development_dependency 'pry'
+  gem.add_development_dependency 'puma'
+  gem.add_development_dependency 'rack'
+  gem.add_development_dependency 'rb-inotify'
+  gem.add_development_dependency 'rspec'
+  gem.add_development_dependency 'rubocop'
+  gem.add_development_dependency 'rubocop-capybara'
+  gem.add_development_dependency 'rubocop-rspec'
+  gem.add_development_dependency 'selenium-webdriver', '>= 4.0'
+  gem.add_development_dependency 'thin'
+  gem.add_development_dependency 'watir', '~> 7.0'
 end
diff --git a/spec/features/examples/facebook_api_spec.rb b/spec/features/examples/facebook_api_spec.rb
index e428189c..b2a3f5d1 100644
--- a/spec/features/examples/facebook_api_spec.rb
+++ b/spec/features/examples/facebook_api_spec.rb
@@ -1,8 +1,10 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 require 'base64'
 
 # FIXME: Looks like Facebook API changed recently and this test fails consistently now -RS 2018-03-05
-xdescribe 'Facebook API example', type: :feature, js: true do
+xdescribe 'Facebook API example', :js, type: :feature do
   before do
     proxy.stub('https://www.facebook.com:443/dialog/oauth').and_return(proc do |params, _, _|
       # mock a signed request from facebook.  the JS api never verifies the
@@ -15,7 +17,7 @@
     proxy.stub('https://graph.facebook.com:443/me').and_return(jsonp: { name: 'Tester 1' })
   end
 
-  it 'should show me as logged-in' do
+  it 'shows me as logged-in' do
     visit '/facebook_api.html'
     click_on 'Login'
     expect(page).to have_content 'Hi, Tester 1'
diff --git a/spec/features/examples/intercept_request_spec.rb b/spec/features/examples/intercept_request_spec.rb
index f9520890..e694f3cf 100644
--- a/spec/features/examples/intercept_request_spec.rb
+++ b/spec/features/examples/intercept_request_spec.rb
@@ -1,12 +1,14 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 require 'timeout'
 
-describe 'intercept request example', type: :feature, js: true do
+describe 'intercept request example', :js, type: :feature do
   before do
     Billy.config.record_stub_requests = true
   end
 
-  it 'should intercept a GET request directly' do
+  it 'intercepts a GET request directly' do
     stub = proxy.stub('http://example.com/').and_return(
       headers: { 'Access-Control-Allow-Origin' => '*' },
       code: 200
@@ -16,13 +18,13 @@
     expect(stub.requests).not_to be_empty
   end
 
-  it 'should intercept a POST request through an intermediary page' do
+  it 'intercepts a POST request through an intermediary page' do
     stub = proxy.stub('http://example.com/', method: 'post').and_return(
       headers: { 'Access-Control-Allow-Origin' => '*' },
       code: 200
     )
     visit '/intercept_request.html'
-    Timeout::timeout(5) do
+    Timeout.timeout(5) do
       sleep(0.1) until stub.has_requests?
     end
     request = stub.requests.shift
diff --git a/spec/features/examples/post_api_spec.rb b/spec/features/examples/post_api_spec.rb
index 6dce722f..298223f1 100644
--- a/spec/features/examples/post_api_spec.rb
+++ b/spec/features/examples/post_api_spec.rb
@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
-describe 'jQuery POST API example', type: :feature, js: true do
+describe 'jQuery POST API example', :js, type: :feature do
   before do
     proxy.stub('http://example.com/api', method: 'post').and_return(
       headers: { 'Access-Control-Allow-Origin' => '*' },
diff --git a/spec/features/examples/preflight_request_spec.rb b/spec/features/examples/preflight_request_spec.rb
index 987872e2..3cba7fc5 100644
--- a/spec/features/examples/preflight_request_spec.rb
+++ b/spec/features/examples/preflight_request_spec.rb
@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
-describe 'jQuery preflight request example', type: :feature, js: true do
+describe 'jQuery preflight request example', :js, type: :feature do
   let(:url) { 'http://example.com/api' }
 
   before do
diff --git a/spec/features/examples/tumblr_api_spec.rb b/spec/features/examples/tumblr_api_spec.rb
index 054024ee..615c97a0 100644
--- a/spec/features/examples/tumblr_api_spec.rb
+++ b/spec/features/examples/tumblr_api_spec.rb
@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 RSpec.shared_examples 'tumblr/expectations' do
-  it 'should show news stories' do
+  it 'shows news stories' do
     visit '/tumblr_api.html'
     expect(page).to have_link('News Item 1', href: 'http://example.com/news/1')
     expect(page).to have_content('News item 1 content here')
@@ -10,7 +12,7 @@
   end
 end
 
-describe 'Tumblr API example', type: :feature, js: true do
+describe 'Tumblr API example', :js, type: :feature do
   context 'without scope external references' do
     before do
       proxy.stub('http://blog.howmanyleft.co.uk/api/read/json').and_return(
@@ -27,7 +29,8 @@
               'regular-body' => 'News item 2 content here'
             }
           ]
-        })
+        }
+      )
     end
 
     include_examples 'tumblr/expectations'
diff --git a/spec/lib/billy/cache_spec.rb b/spec/lib/billy/cache_spec.rb
index 9a872c02..a839cf8b 100644
--- a/spec/lib/billy/cache_spec.rb
+++ b/spec/lib/billy/cache_spec.rb
@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::Cache do
-  let(:cache) { Billy::Cache.instance }
+  let(:cache) { described_class.instance }
   let(:params) { '?foo=bar' }
   let(:callback) { '&callback=quux' }
   let(:fragment) { '#baz' }
@@ -18,12 +20,15 @@
       it 'is a no-op if there are no params' do
         expect(cache.format_url(base_url)).to eq base_url
       end
+
       it 'appends params if there are params' do
         expect(cache.format_url(params_url)).to eq params_url
       end
+
       it 'appends params and fragment if both are present' do
         expect(cache.format_url(params_fragment_url)).to eq params_fragment_url
       end
+
       it 'does not raise error for URLs with pipes' do
         expect { cache.format_url(pipe_url) }.not_to raise_error
       end
@@ -34,7 +39,7 @@
         end
 
         it 'omits the params listed in Billy.config.dynamic_jsonp_keys' do
-          allow(Billy.config).to receive(:dynamic_jsonp_keys) { ['foo'] }
+          allow(Billy.config).to receive(:dynamic_jsonp_keys).and_return(['foo'])
 
           expect(cache.format_url(params_url_with_callback, false, true)).to eq "#{base_url}?callback=quux"
         end
@@ -49,9 +54,11 @@
       it 'is a no-op if there are no params' do
         expect(cache.format_url(base_url, true)).to eq base_url
       end
+
       it 'omits params if there are params' do
         expect(cache.format_url(params_url, true)).to eq base_url
       end
+
       it 'omits params and fragment if both are present' do
         expect(cache.format_url(params_fragment_url, true)).to eq base_url
       end
@@ -64,7 +71,7 @@
 
       let(:regex_to_match_analytics_urls_only) do
         # Note that it matches the forward slash at the end of the URL, which doesn't match regular_url:
-        /www\.example\-analytics\.com\/user\//
+        %r{www\.example-analytics\.com/user/}
       end
 
       before do
@@ -74,8 +81,10 @@
       end
 
       it "has one cache key for the two analytics urls that match, and a separate one for the other that doesn't" do
-        expect(cache.key('post', analytics_url1, 'body', cache_scope)).to eq cache.key('post', analytics_url2, 'body', cache_scope)
-        expect(cache.key('post', analytics_url1, 'body', cache_scope)).not_to eq cache.key('post', regular_url, 'body', cache_scope)
+        expect(cache.key('post', analytics_url1, 'body',
+                         cache_scope)).to eq cache.key('post', analytics_url2, 'body', cache_scope)
+        expect(cache.key('post', analytics_url1, 'body',
+                         cache_scope)).not_to eq cache.key('post', regular_url, 'body', cache_scope)
       end
 
       it 'More specifically, the cache keys should be identical for the 2 analytics urls' do
@@ -91,32 +100,30 @@
 
     context 'with cache_request_body_methods set' do
       before do
-        allow(Billy.config).to receive(:cache_request_body_methods) {
-          ['patch']
-        }
+        allow(Billy.config).to receive(:cache_request_body_methods).and_return(['patch'])
       end
 
-      context "for requests with methods specified in cache_request_body_methods" do
-        # Note: Body hashing logic is currently commented out in Billy::Cache#key (lines 99-104)
+      context 'for requests with methods specified in cache_request_body_methods' do
+        # NOTE: Body hashing logic is currently commented out in Billy::Cache#key (lines 99-104)
         # So cache keys dont differ based on body content even for cache_request_body_methods
-        it "should have the same cache key for requests with different bodies (body hashing disabled)" do
-          key1 = cache.key('patch', "http://example.com", "body1", cache_scope)
-          key2 = cache.key('patch', "http://example.com", "body2", cache_scope)
+        it 'has the same cache key for requests with different bodies (body hashing disabled)' do
+          key1 = cache.key('patch', 'http://example.com', 'body1', cache_scope)
+          key2 = cache.key('patch', 'http://example.com', 'body2', cache_scope)
           # Body hashing is commented out, so keys are the same regardless of body
-            expect(key1).to eq key2
+          expect(key1).to eq key2
         end
 
-        it "should have the same cache key for requests with the same bodies" do
-          key1 = cache.key('patch', "http://example.com", "body1", cache_scope)
-          key2 = cache.key('patch', "http://example.com", "body1", cache_scope)
+        it 'has the same cache key for requests with the same bodies' do
+          key1 = cache.key('patch', 'http://example.com', 'body1', cache_scope)
+          key2 = cache.key('patch', 'http://example.com', 'body1', cache_scope)
           expect(key1).to eq key2
         end
       end
 
-      it "should have the same cache key for request with different bodies if their methods are not included in cache_request_body_methods" do
-          key1 = cache.key('put', "http://example.com", "body1", cache_scope)
-          key2 = cache.key('put', "http://example.com", "body2", cache_scope)
-          expect(key1).to eq key2
+      it 'has the same cache key for request with different bodies if their methods are not included in cache_request_body_methods' do
+        key1 = cache.key('put', 'http://example.com', 'body1', cache_scope)
+        key2 = cache.key('put', 'http://example.com', 'body2', cache_scope)
+        expect(key1).to eq key2
       end
     end
   end
@@ -124,37 +131,37 @@
   describe 'key' do
     context 'with use_ignore_params set to false' do
       before do
-        allow(Billy.config).to receive(:use_ignore_params) { false }
+        allow(Billy.config).to receive(:use_ignore_params).and_return(false)
       end
 
-      it "should use the same cache key if the base url IS NOT whitelisted in allow_params" do
+      it 'uses the same cache key if the base url IS NOT whitelisted in allow_params' do
         key1 = cache.key('put', params_url, 'body', cache_scope)
         key2 = cache.key('put', params_url, 'body', cache_scope)
         expect(key1).to eq key2
       end
 
-      it "should have the same cache key if the base IS whitelisted in allow_params" do
+      it 'has the same cache key if the base IS whitelisted in allow_params' do
         allow(Billy.config).to receive(:allow_params) { [base_url] }
         key1 = cache.key('put', params_url, 'body', cache_scope)
         key2 = cache.key('put', params_url, 'body', cache_scope)
         expect(key1).to eq key2
       end
 
-      it "should have different cache keys if the base url is added in between two requests" do
+      it 'has different cache keys if the base url is added in between two requests' do
         key1 = cache.key('put', params_url, 'body', cache_scope)
         allow(Billy.config).to receive(:allow_params) { [base_url] }
         key2 = cache.key('put', params_url, 'body', cache_scope)
         expect(key1).not_to eq key2
       end
 
-      it "should not use ignore_params when whitelisted" do
+      it 'does not use ignore_params when whitelisted' do
         allow(Billy.config).to receive(:allow_params) { [base_url] }
         expect(cache).to receive(:format_url).once.with(params_url, true).and_call_original
         expect(cache).to receive(:format_url).once.with(params_url, false).and_call_original
         cache.key('put', params_url, 'body', cache_scope)
       end
 
-      it "should use ignore_params when not whitelisted" do
+      it 'uses ignore_params when not whitelisted' do
         expect(cache).to receive(:format_url).twice.with(params_url, true).and_call_original
         cache.key('put', params_url, 'body', cache_scope)
       end
diff --git a/spec/lib/billy/handlers/cache_handler_spec.rb b/spec/lib/billy/handlers/cache_handler_spec.rb
index 5fc97bf6..851ee5a9 100644
--- a/spec/lib/billy/handlers/cache_handler_spec.rb
+++ b/spec/lib/billy/handlers/cache_handler_spec.rb
@@ -1,15 +1,17 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::CacheHandler do
-  let(:handler) { Billy::CacheHandler.new }
+  let(:handler) { described_class.new }
   let(:request_url) { 'http://example.test:8080/index?some=param&callback=dynamicCallback5678' }
   let(:request) do
     {
-      method:   'post',
-      url:      request_url,
-      headers:  { 'Accept-Encoding'  => 'gzip',
-                  'Cache-Control'    => 'no-cache' },
-      body:     'Some body'
+      method: 'post',
+      url: request_url,
+      headers: { 'Accept-Encoding' => 'gzip',
+                 'Cache-Control' => 'no-cache' },
+      body: 'Some body'
     }
   end
   let(:cache_scope) { 0 }
@@ -48,17 +50,19 @@
                                     request[:url],
                                     request[:headers],
                                     request[:body],
-                                    cache_scope)).to be nil
+                                    cache_scope)).to be_nil
     end
 
     it 'returns a cached response if the request can be handled' do
       expect(Billy::Cache.instance).to receive(:cached?).and_return(true)
-      expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' }, content: 'The response body')
+      expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' },
+                                                                  content: 'The response body')
       expect(handler.handle_request(request[:method],
                                     request[:url],
                                     request[:headers],
                                     request[:body],
-                                    cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' }, content: 'The response body')
+                                    cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' },
+                                                         content: 'The response body')
     end
 
     context 'updating jsonp callback names enabled' do
@@ -68,60 +72,66 @@
 
       it 'updates the cached response if the callback is dynamic' do
         expect(Billy::Cache.instance).to receive(:cached?).and_return(true)
-        expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' }, content: 'dynamicCallback1234({"yolo":"kitten"})')
+        expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' },
+                                                                    content: 'dynamicCallback1234({"yolo":"kitten"})')
         expect(handler.handle_request(request[:method],
                                       request[:url],
                                       request[:headers],
                                       request[:body],
-                                      cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' }, content: 'dynamicCallback5678({"yolo":"kitten"})')
+                                      cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' },
+                                                           content: 'dynamicCallback5678({"yolo":"kitten"})')
       end
 
       it 'is flexible about the format of the response body' do
         expect(Billy::Cache.instance).to receive(:cached?).and_return(true)
-        expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' }, content: "/**/ dynamicCallback1234(\n{\"yolo\":\"kitten\"})")
+        expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' },
+                                                                    content: "/**/ dynamicCallback1234(\n{\"yolo\":\"kitten\"})")
         expect(handler.handle_request(request[:method],
                                       request[:url],
                                       request[:headers],
                                       request[:body],
-                                      cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' }, content: "/**/ dynamicCallback5678(\n{\"yolo\":\"kitten\"})")
+                                      cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' },
+                                                           content: "/**/ dynamicCallback5678(\n{\"yolo\":\"kitten\"})")
       end
 
       it 'does not interfere with non-jsonp requests' do
-        jsonp_request = request
+        request
         other_request = {
-          method:  'get',
-          url:     'http://example.test:8080/index?hanukkah=latkes',
+          method: 'get',
+          url: 'http://example.test:8080/index?hanukkah=latkes',
           headers: { 'Accept-Encoding' => 'gzip', 'Cache-Control' => 'no-cache' },
-          body:    'no jsonp'
+          body: 'no jsonp'
         }
 
-        allow(Billy::Cache.instance).to receive(:cached?).and_return(true)
-        allow(Billy::Cache.instance).to receive(:fetch).and_return(status: 200,
-                                                                   headers: { 'Connection' => 'close' },
-                                                                   content: 'no jsonp but has parentheses()')
+        allow(Billy::Cache.instance).to receive_messages(cached?: true, fetch: { status: 200,
+                                                                                 headers: { 'Connection' => 'close' },
+                                                                                 content: 'no jsonp but has parentheses()' })
 
         expect(handler.handle_request(other_request[:method],
                                       other_request[:url],
                                       other_request[:headers],
                                       other_request[:body],
-                                      cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' }, content: 'no jsonp but has parentheses()')
+                                      cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' },
+                                                           content: 'no jsonp but has parentheses()')
       end
 
       context 'when after_cache_handles_request is set' do
-        it "should call the callback with the request and response" do
+        it 'calls the callback with the request and response' do
           allow(Billy.config).to receive(:after_cache_handles_request) do
             proc do |request, response|
-              response[:headers]['Access-Control-Allow-Origin'] = "*"
+              response[:headers]['Access-Control-Allow-Origin'] = '*'
               response[:content] = request[:body]
             end
           end
           expect(Billy::Cache.instance).to receive(:cached?).and_return(true)
-          expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' }, content: 'The response body')
+          expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200,
+                                                                      headers: { 'Connection' => 'close' }, content: 'The response body')
           expect(handler.handle_request(request[:method],
                                         request[:url],
                                         request[:headers],
                                         request[:body],
-                                        cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close', 'Access-Control-Allow-Origin' => "*" }, content: 'Some body')
+                                        cache_scope)).to eql(status: 200,
+                                                             headers: { 'Connection' => 'close', 'Access-Control-Allow-Origin' => '*' }, content: 'Some body')
         end
       end
 
@@ -135,14 +145,16 @@
           end
         end
 
-        it 'should call the callback with the specified name' do
+        it 'calls the callback with the specified name' do
           expect(Billy::Cache.instance).to receive(:cached?).and_return(true)
-          expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' }, content: 'dynamicCallback1234({"yolo":"kitten"})')
+          expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200,
+                                                                      headers: { 'Connection' => 'close' }, content: 'dynamicCallback1234({"yolo":"kitten"})')
           expect(handler.handle_request(request[:method],
                                         request[:url],
                                         request[:headers],
                                         request[:body],
-                                        cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' }, content: 'dynamicCallback5678({"yolo":"kitten"})')
+                                        cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' },
+                                                             content: 'dynamicCallback5678({"yolo":"kitten"})')
         end
       end
     end
@@ -154,12 +166,14 @@
 
       it 'does not change the response' do
         expect(Billy::Cache.instance).to receive(:cached?).and_return(true)
-        expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' }, content: 'dynamicCallback1234({"yolo":"kitten"})')
+        expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' },
+                                                                    content: 'dynamicCallback1234({"yolo":"kitten"})')
         expect(handler.handle_request(request[:method],
                                       request[:url],
                                       request[:headers],
                                       request[:body],
-                                      cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' }, content: 'dynamicCallback1234({"yolo":"kitten"})')
+                                      cache_scope)).to eql(status: 200, headers: { 'Connection' => 'close' },
+                                                           content: 'dynamicCallback1234({"yolo":"kitten"})')
       end
     end
 
@@ -170,13 +184,13 @@
                                     request[:url],
                                     request[:headers],
                                     request[:body],
-                                    cache_scope)).to be nil
+                                    cache_scope)).to be_nil
     end
 
     context 'network delay simulation' do
       before do
-        allow(Billy::Cache.instance).to receive(:cached?).and_return(true)
-        allow(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' }, content: 'dynamicCallback1234({"yolo":"kitten"})')
+        allow(Billy::Cache.instance).to receive_messages(cached?: true, fetch: { status: 200, headers: { 'Connection' => 'close' },
+                                                                                 content: 'dynamicCallback1234({"yolo":"kitten"})' })
       end
 
       context 'when cache_simulates_network_delays is disabled' do
diff --git a/spec/lib/billy/handlers/handler_spec.rb b/spec/lib/billy/handlers/handler_spec.rb
index 71994f7a..5287e67d 100644
--- a/spec/lib/billy/handlers/handler_spec.rb
+++ b/spec/lib/billy/handlers/handler_spec.rb
@@ -1,9 +1,13 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::Handler do
   let(:handler) { Class.new { include Billy::Handler }.new }
+
   it '#handle_request raises an error if not overridden' do
-    expect(handler.handle_request(nil, nil, nil, nil)).to eql(error: 'The handler has not overridden the handle_request method!')
+    expect(handler.handle_request(nil, nil, nil,
+                                  nil)).to eql(error: 'The handler has not overridden the handle_request method!')
   end
 
   it '#handles_request returns false by default' do
diff --git a/spec/lib/billy/handlers/proxy_handler_spec.rb b/spec/lib/billy/handlers/proxy_handler_spec.rb
index ad170480..d3d5855d 100644
--- a/spec/lib/billy/handlers/proxy_handler_spec.rb
+++ b/spec/lib/billy/handlers/proxy_handler_spec.rb
@@ -1,14 +1,17 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::ProxyHandler do
-  subject { Billy::ProxyHandler.new }
+  subject { described_class.new }
+
   let(:request) do
     {
-      method:   'post',
-      url:      'http://usern:pw@example.test:8080/index?some=param',
-      headers:  { 'Accept-Encoding'  => 'gzip',
-                  'Cache-Control'    => 'no-cache' },
-      body:     'Some body'
+      method: 'post',
+      url: 'http://usern:pw@example.test:8080/index?some=param',
+      headers: { 'Accept-Encoding' => 'gzip',
+                 'Cache-Control' => 'no-cache' },
+      body: 'Some body'
     }
   end
   let(:cache_scope) { 0 }
@@ -27,6 +30,7 @@
                                         cache_scope)).to be true
       end
     end
+
     context 'with non-whitelisted requests disabled' do
       before do
         expect(Billy.config).to receive(:non_whitelisted_requests_disabled).and_return(true)
@@ -43,7 +47,7 @@
       context 'a whitelisted host' do
         context 'with a blacklisted path' do
           before do
-            expect(Billy.config).to receive(:path_blacklist) { ['/index'] }
+            expect(Billy.config).to receive(:path_blacklist).and_return(['/index'])
           end
 
           it 'does not handle requests for blacklisted paths' do
@@ -57,7 +61,7 @@
 
         context 'as a regex' do
           before do
-            expect(Billy.config).to receive(:whitelist) { [%r{example\.test\/a}] }
+            expect(Billy.config).to receive(:whitelist).and_return([%r{example\.test/a}])
           end
 
           it 'handles requests for the host without a port' do
@@ -79,7 +83,7 @@
 
         context 'without a port' do
           before do
-            expect(Billy.config).to receive(:whitelist) { ['example.test'] }
+            expect(Billy.config).to receive(:whitelist).and_return(['example.test'])
           end
 
           it 'handles requests for the host without a port' do
@@ -101,7 +105,7 @@
 
         context 'with a port' do
           before do
-            expect(Billy.config).to receive(:whitelist) { ['example.test:8080'] }
+            expect(Billy.config).to receive(:whitelist).and_return(['example.test:8080'])
           end
 
           it 'does not handle requests whitelisted for a specific port' do
@@ -131,7 +135,7 @@
                                     request[:url],
                                     request[:headers],
                                     request[:body],
-                                    cache_scope)).to be nil
+                                    cache_scope)).to be_nil
     end
 
     context 'with a handled request' do
@@ -179,15 +183,13 @@
                                       request[:url],
                                       request[:headers],
                                       request[:body],
-                                      cache_scope)).to be nil
+                                      cache_scope)).to be_nil
       end
 
       it 'caches the response if cacheable' do
         # cacheable? requires Billy.config.cache and refresh_persisted_cache to be true
-        allow(Billy.config).to receive(:cache).and_return(true)
-        allow(Billy.config).to receive(:refresh_persisted_cache).and_return(true)
-        allow(Billy.config).to receive(:whitelist).and_return([])
-        allow(Billy.config).to receive(:path_blacklist).and_return(['/index'])
+        allow(Billy.config).to receive_messages(cache: true, refresh_persisted_cache: true, whitelist: [],
+                                                path_blacklist: ['/index'])
         expect(Billy::Cache.instance).to receive(:store)
         subject.handle_request(request[:method],
                                request[:url],
@@ -197,13 +199,12 @@
       end
 
       it 'uses the timeouts defined in configuration' do
-        allow(Billy.config).to receive(:proxied_request_inactivity_timeout).and_return(42)
-        allow(Billy.config).to receive(:proxied_request_connect_timeout).and_return(24)
+        allow(Billy.config).to receive_messages(proxied_request_inactivity_timeout: 42,
+                                                proxied_request_connect_timeout: 24)
 
         expect(EventMachine::HttpRequest).to receive(:new).with(request[:url],
-                                                                inactivity_timeout: 42,
-                                                                connect_timeout: 24
-        )
+                                                                { inactivity_timeout: 42,
+                                                                  connect_timeout: 24 })
 
         subject.handle_request(request[:method],
                                request[:url],
@@ -213,14 +214,12 @@
       end
 
       it 'uses the internal proxy settings defined in configuration' do
-        allow(Billy.config).to receive(:proxied_request_host).and_return('10.10.10.10')
-        allow(Billy.config).to receive(:proxied_request_port).and_return('2080')
+        allow(Billy.config).to receive_messages(proxied_request_host: '10.10.10.10', proxied_request_port: '2080')
 
         expect(EventMachine::HttpRequest).to receive(:new).with(request[:url],
-                                                                inactivity_timeout: 10,
-                                                                connect_timeout: 5,
-                                                                proxy: { host: '10.10.10.10', port: '2080' }
-        )
+                                                                { inactivity_timeout: 10,
+                                                                  connect_timeout: 5,
+                                                                  proxy: { host: '10.10.10.10', port: '2080' } })
 
         subject.handle_request(request[:method],
                                request[:url],
@@ -234,15 +233,15 @@
   describe '#build_request_options' do
     it 'creates authorization header when URL has basic auth' do
       request_options = subject.send(:build_request_options, request[:url],
-                                                             request[:headers],
-                                                             request[:body])
+                                     request[:headers],
+                                     request[:body])
       expect(request_options[:head]).to have_key 'authorization'
     end
 
     it 'does not include authorization header without basic auth' do
-      request_options = subject.send(:build_request_options, request[:url].gsub('usern:pw@',''),
-                                                             request[:headers],
-                                                             request[:body])
+      request_options = subject.send(:build_request_options, request[:url].gsub('usern:pw@', ''),
+                                     request[:headers],
+                                     request[:body])
       expect(request_options[:head]).not_to have_key 'authorization'
     end
   end
diff --git a/spec/lib/billy/handlers/request_handler_spec.rb b/spec/lib/billy/handlers/request_handler_spec.rb
index 2258de4c..8d6fb5ec 100644
--- a/spec/lib/billy/handlers/request_handler_spec.rb
+++ b/spec/lib/billy/handlers/request_handler_spec.rb
@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::RequestHandler do
-  subject { Billy::RequestHandler.new }
+  subject { described_class.new }
 
   it 'implements Handler' do
     expect(subject).to be_a Billy::Handler
@@ -22,7 +24,7 @@
   end
 
   context 'with stubbed handlers' do
-    let(:args) { %w(get url headers body) }
+    let(:args) { %w[get url headers body] }
     let(:stub_handler) { double('StubHandler') }
     let(:cache_handler) { double('CacheHandler') }
     let(:proxy_handler) { double('ProxyHandler') }
@@ -38,10 +40,10 @@
       allow(subject).to receive(:handlers).and_return(handlers)
     end
 
-    # Note: handles_request? is commented out in the lib, so we skip these tests
+    # NOTE: handles_request? is commented out in the lib, so we skip these tests
     describe '#handles_request?', skip: 'handles_request? method is commented out in lib' do
       it 'returns false if no handlers handle the request' do
-        handlers.each do |_key, handler|
+        handlers.each_value do |handler|
           allow(handler).to receive(:handles_request?).and_return(false)
         end
         expect(subject.handles_request?(*args)).to be false
@@ -68,49 +70,61 @@
 
     describe '#handle_request' do
       before do
-        allow(Billy::config).to receive(:record_requests).and_return(true)
+        allow(Billy.config).to receive(:record_requests).and_return(true)
       end
 
       it 'returns stubbed responses' do
-        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return({ cache_key: 'test' })
-        expect(cache_handler).to_not receive(:handle_request)
-        expect(proxy_handler).to_not receive(:handle_request)
+        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                              anything).and_return({ cache_key: 'test' })
+        expect(cache_handler).not_to receive(:handle_request)
+        expect(proxy_handler).not_to receive(:handle_request)
         result = subject.handle_request(*args)
         expect(result).to include(cache_key: 'test')
         expect(subject.requests.first).to include(status: :complete, handler: :stubs, method: 'get', url: 'url')
       end
 
       it 'returns cached responses' do
-        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return(nil)
-        expect(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return({ cache_key: 'test' })
-        expect(proxy_handler).to_not receive(:handle_request)
+        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                              anything).and_return(nil)
+        expect(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                               anything).and_return({ cache_key: 'test' })
+        expect(proxy_handler).not_to receive(:handle_request)
         result = subject.handle_request(*args)
         expect(result).to include(cache_key: 'test')
         expect(subject.requests.first).to include(status: :complete, handler: :cache, method: 'get', url: 'url')
       end
 
       it 'returns proxied responses' do
-        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return(nil)
-        expect(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return(nil)
-        expect(proxy_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return({ cache_key: 'test' })
+        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                              anything).and_return(nil)
+        expect(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                               anything).and_return(nil)
+        expect(proxy_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                               anything).and_return({ cache_key: 'test' })
         result = subject.handle_request(*args)
         expect(result).to include(cache_key: 'test')
         expect(subject.requests.first).to include(status: :complete, handler: :proxy, method: 'get', url: 'url')
       end
 
       it 'returns an error hash if request is not handled' do
-        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return(nil)
-        expect(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return(nil)
-        expect(proxy_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return(nil)
+        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                              anything).and_return(nil)
+        expect(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                               anything).and_return(nil)
+        expect(proxy_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                               anything).and_return(nil)
         expect(subject.handle_request(*args)).to eql(error: 'Connection to url not cached and new http connections are disabled')
         expect(subject.requests.first).to include(status: :complete, handler: :error, method: 'get', url: 'url')
       end
 
       it 'returns an error hash with body message if request cached based on body is not handled' do
         args[0] = Billy.config.cache_request_body_methods[0]
-        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return(nil)
-        expect(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return(nil)
-        expect(proxy_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_return(nil)
+        expect(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                              anything).and_return(nil)
+        expect(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                               anything).and_return(nil)
+        expect(proxy_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                               anything).and_return(nil)
         expect(subject.handle_request(*args)).to eql(error: "Connection to url with body 'body' not cached and new http connections are disabled")
         expect(subject.requests.first).to include(status: :complete, handler: :error, method: 'post', url: 'url')
       end
@@ -120,14 +134,17 @@
         allow(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything)
         allow(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything)
 
-        allow(proxy_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_raise("Any Proxy Error")
-        expect(subject.handle_request(*args)).to eql(error: "Any Proxy Error")
+        allow(proxy_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                              anything).and_raise('Any Proxy Error')
+        expect(subject.handle_request(*args)).to eql(error: 'Any Proxy Error')
 
-        allow(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_raise("Any Cache Error")
-        expect(subject.handle_request(*args)).to eql(error: "Any Cache Error")
+        allow(cache_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                              anything).and_raise('Any Cache Error')
+        expect(subject.handle_request(*args)).to eql(error: 'Any Cache Error')
 
-        allow(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything, anything).and_raise("Any Stub Error")
-        expect(subject.handle_request(*args)).to eql(error: "Any Stub Error")
+        allow(stub_handler).to receive(:handle_request).with(anything, anything, anything, anything,
+                                                             anything).and_raise('Any Stub Error')
+        expect(subject.handle_request(*args)).to eql(error: 'Any Stub Error')
       end
     end
 
@@ -147,7 +164,7 @@
 
     describe '#reset' do
       it 'resets all of the handlers' do
-        handlers.each do |_key, handler|
+        handlers.each_value do |handler|
           expect(handler).to receive(:reset)
         end
         expect(subject.request_log).to receive(:reset)
diff --git a/spec/lib/billy/handlers/request_log_spec.rb b/spec/lib/billy/handlers/request_log_spec.rb
index c096f9ec..0ea1b755 100644
--- a/spec/lib/billy/handlers/request_log_spec.rb
+++ b/spec/lib/billy/handlers/request_log_spec.rb
@@ -1,12 +1,14 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::RequestLog do
-  let(:request_log) { Billy::RequestLog.new }
+  let(:request_log) { described_class.new }
   let(:cache_scope) { 0 }
 
   describe '#record' do
     it 'returns the request details if record_requests is enabled' do
-      allow(Billy::config).to receive(:record_requests).and_return(true)
+      allow(Billy.config).to receive(:record_requests).and_return(true)
       expected_request = {
         scope: cache_scope,
         cache_key: nil,
@@ -21,14 +23,14 @@
     end
 
     it 'returns nil if record_requests is disabled' do
-      allow(Billy::config).to receive(:record_requests).and_return(false)
+      allow(Billy.config).to receive(:record_requests).and_return(false)
       expect(request_log.record(:method, :url, :headers, :body, cache_scope)).to be_nil
     end
   end
 
   describe '#complete' do
     it 'marks the request as complete if record_requests is enabled' do
-      allow(Billy::config).to receive(:record_requests).and_return(true)
+      allow(Billy.config).to receive(:record_requests).and_return(true)
 
       request = request_log.record(:method, :url, :headers, :body, cache_scope)
       expected_request = {
@@ -45,7 +47,7 @@
     end
 
     it 'marks the request as complete if record_requests is disabled' do
-      allow(Billy::config).to receive(:record_requests).and_return(false)
+      allow(Billy.config).to receive(:record_requests).and_return(false)
       expect(request_log.complete(nil, :handler, :cache_key)).to be_nil
     end
   end
@@ -56,7 +58,7 @@
     end
 
     it 'returns the currently known requests' do
-      allow(Billy::config).to receive(:record_requests).and_return(true)
+      allow(Billy.config).to receive(:record_requests).and_return(true)
 
       request1 = request_log.record(:method, :url, :headers, :body, cache_scope)
       request2 = request_log.record(:method, :url, :headers, :body, cache_scope)
@@ -66,7 +68,7 @@
 
   describe '#reset' do
     it 'resets known requests' do
-      allow(Billy::config).to receive(:record_requests).and_return(true)
+      allow(Billy.config).to receive(:record_requests).and_return(true)
 
       request1 = request_log.record(:method, :url, :headers, :body, cache_scope)
       request2 = request_log.record(:method, :url, :headers, :body, cache_scope)
diff --git a/spec/lib/billy/handlers/stub_handler_spec.rb b/spec/lib/billy/handlers/stub_handler_spec.rb
index 32fda434..ce85a1da 100644
--- a/spec/lib/billy/handlers/stub_handler_spec.rb
+++ b/spec/lib/billy/handlers/stub_handler_spec.rb
@@ -1,14 +1,16 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::StubHandler do
-  let(:handler) { Billy::StubHandler.new }
+  let(:handler) { described_class.new }
   let(:request) do
     {
-      method:   'GET',
-      url:      'http://example.test:8080/index?some=param',
-      headers:  { 'Accept-Encoding'  => 'gzip',
-                  'Cache-Control'    => 'no-cache' },
-      body:     'Some body'
+      method: 'GET',
+      url: 'http://example.test:8080/index?some=param',
+      headers: { 'Accept-Encoding' => 'gzip',
+                 'Cache-Control' => 'no-cache' },
+      body: 'Some body'
     }
   end
   let(:cache_scope) { 0 }
@@ -28,7 +30,7 @@
   describe '#handle_request' do
     it 'returns nil if the request is not stubbed' do
       expect(handler).to receive(:handles_request?).and_return(false)
-      expect(handler.handle_request(nil, nil, nil, nil, cache_scope)).to be nil
+      expect(handler.handle_request(nil, nil, nil, nil, cache_scope)).to be_nil
     end
 
     it 'returns a response hash if the request is stubbed' do
diff --git a/spec/lib/billy/proxy_connection_spec.rb b/spec/lib/billy/proxy_connection_spec.rb
index dc8514b4..e5c241a0 100644
--- a/spec/lib/billy/proxy_connection_spec.rb
+++ b/spec/lib/billy/proxy_connection_spec.rb
@@ -1,20 +1,22 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::ProxyConnection do
-  context '#prepare_response_headers_for_evma_httpserver' do
-    let(:subject) { Billy::ProxyConnection.new('') }
-    
-    it 'should remove duplicated headers fields' do
-        provided_headers = {
-            'transfer-encoding' => '',
-            'content-length' => '',
-            'content-encoding' => '',
-            'key' => 'value'
-        }
-        expected_headers = { 'key' => 'value' }
-        headers = subject.send(:prepare_response_headers_for_evma_httpserver, provided_headers)
+  describe '#prepare_response_headers_for_evma_httpserver' do
+    let(:subject) { described_class.new('') }
+
+    it 'removes duplicated headers fields' do
+      provided_headers = {
+        'transfer-encoding' => '',
+        'content-length' => '',
+        'content-encoding' => '',
+        'key' => 'value'
+      }
+      expected_headers = { 'key' => 'value' }
+      headers = subject.send(:prepare_response_headers_for_evma_httpserver, provided_headers)
 
-        expect(headers).to eql expected_headers
+      expect(headers).to eql expected_headers
     end
   end
 end
diff --git a/spec/lib/billy/proxy_request_stub_spec.rb b/spec/lib/billy/proxy_request_stub_spec.rb
index 4329c931..3cf8dcb5 100644
--- a/spec/lib/billy/proxy_request_stub_spec.rb
+++ b/spec/lib/billy/proxy_request_stub_spec.rb
@@ -1,86 +1,88 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::ProxyRequestStub do
-  context '#matches?' do
-    it 'should match urls and methods' do
-      expect(Billy::ProxyRequestStub.new('http://example.com')
+  describe '#matches?' do
+    it 'matches urls and methods' do
+      expect(described_class.new('http://example.com')
         .matches?('GET', 'http://example.com')).to be
-      expect(Billy::ProxyRequestStub.new('http://example.com')
-        .matches?('POST', 'http://example.com')).to_not be
+      expect(described_class.new('http://example.com')
+        .matches?('POST', 'http://example.com')).not_to be
 
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :get)
+      expect(described_class.new('http://example.com', method: :get)
         .matches?('GET', 'http://example.com')).to be
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :post)
-        .matches?('GET', 'http://example.com')).to_not be
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :options)
-        .matches?('GET', 'http://example.com')).to_not be
+      expect(described_class.new('http://example.com', method: :post)
+        .matches?('GET', 'http://example.com')).not_to be
+      expect(described_class.new('http://example.com', method: :options)
+        .matches?('GET', 'http://example.com')).not_to be
 
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :post)
+      expect(described_class.new('http://example.com', method: :post)
         .matches?('POST', 'http://example.com')).to be
-      expect(Billy::ProxyRequestStub.new('http://fooxample.com', method: :post)
-        .matches?('POST', 'http://example.com')).to_not be
-        expect(Billy::ProxyRequestStub.new('http://fooxample.com', method: :options)
-          .matches?('POST', 'http://example.com')).to_not be
+      expect(described_class.new('http://fooxample.com', method: :post)
+        .matches?('POST', 'http://example.com')).not_to be
+      expect(described_class.new('http://fooxample.com', method: :options)
+        .matches?('POST', 'http://example.com')).not_to be
 
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :options)
+      expect(described_class.new('http://example.com', method: :options)
         .matches?('OPTIONS', 'http://example.com')).to be
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :options)
-        .matches?('OPTIONS', 'http://zzzzzexample.com')).to_not be
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :post)
-        .matches?('OPTIONS', 'http://example.com')).to_not be
+      expect(described_class.new('http://example.com', method: :options)
+        .matches?('OPTIONS', 'http://zzzzzexample.com')).not_to be
+      expect(described_class.new('http://example.com', method: :post)
+        .matches?('OPTIONS', 'http://example.com')).not_to be
     end
 
-    it 'should match regexps' do
-      expect(Billy::ProxyRequestStub.new(/http:\/\/.+\.com/, method: :post)
+    it 'matches regexps' do
+      expect(described_class.new(%r{http://.+\.com}, method: :post)
         .matches?('POST', 'http://example.com')).to be
-      expect(Billy::ProxyRequestStub.new(/http:\/\/.+\.co\.uk/, method: :get)
-        .matches?('GET', 'http://example.com')).to_not be
+      expect(described_class.new(%r{http://.+\.co\.uk}, method: :get)
+        .matches?('GET', 'http://example.com')).not_to be
     end
 
-    it 'should match up to but not including query strings' do
-      stub = Billy::ProxyRequestStub.new('http://example.com/foo/bar/')
-      expect(stub.matches?('GET', 'http://example.com/foo/')).to_not be
+    it 'matches up to but not including query strings' do
+      stub = described_class.new('http://example.com/foo/bar/')
+      expect(stub.matches?('GET', 'http://example.com/foo/')).not_to be
       expect(stub.matches?('GET', 'http://example.com/foo/bar/')).to be
       expect(stub.matches?('GET', 'http://example.com/foo/bar/?baz=bap')).to be
     end
 
-    it 'should match all methods' do
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :all)
+    it 'matches all methods' do
+      expect(described_class.new('http://example.com', method: :all)
         .matches?('GET', 'http://example.com')).to be
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :all)
+      expect(described_class.new('http://example.com', method: :all)
         .matches?('POST', 'http://example.com')).to be
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :all)
+      expect(described_class.new('http://example.com', method: :all)
         .matches?('OPTIONS', 'http://example.com')).to be
-      expect(Billy::ProxyRequestStub.new('http://example.com', method: :all)
+      expect(described_class.new('http://example.com', method: :all)
         .matches?('HEAD', 'http://example.com')).to be
     end
   end
 
-  context "#matches? (with strip_query_params false in config)" do
+  describe '#matches? (with strip_query_params false in config)' do
     before do
       Billy.config.strip_query_params = false
     end
 
-    it 'should not match up to request with query strings' do
-      stub = Billy::ProxyRequestStub.new('http://example.com/foo/bar/')
-      expect(stub.matches?('GET', 'http://example.com/foo/')).to_not be
+    it 'does not match up to request with query strings' do
+      stub = described_class.new('http://example.com/foo/bar/')
+      expect(stub.matches?('GET', 'http://example.com/foo/')).not_to be
       expect(stub.matches?('GET', 'http://example.com/foo/bar/')).to be
-      expect(stub.matches?('GET', 'http://example.com/foo/bar/?baz=bap')).to_not be
+      expect(stub.matches?('GET', 'http://example.com/foo/bar/?baz=bap')).not_to be
     end
   end
 
-  context '#call (without #and_return)' do
-    let(:subject) { Billy::ProxyRequestStub.new('url') }
+  describe '#call (without #and_return)' do
+    let(:subject) { described_class.new('url') }
 
     it 'returns a 204 empty response' do
       expect(subject.call('', '', {}, {}, nil)).to eql [204, { 'Content-Type' => 'text/plain' }, '']
     end
   end
 
-  context '#and_return + #call' do
-    let(:subject) { Billy::ProxyRequestStub.new('url') }
+  describe '#and_return + #call' do
+    let(:subject) { described_class.new('url') }
 
-    it 'should generate bare responses' do
+    it 'generates bare responses' do
       subject.and_return body: 'baz foo bar'
       expect(subject.call('', '', {}, {}, nil)).to eql [
         200,
@@ -89,7 +91,7 @@
       ]
     end
 
-    it 'should generate text responses' do
+    it 'generates text responses' do
       subject.and_return text: 'foo bar baz'
       expect(subject.call('', '', {}, {}, nil)).to eql [
         200,
@@ -98,7 +100,7 @@
       ]
     end
 
-    it 'should generate JSON responses' do
+    it 'generates JSON responses' do
       subject.and_return json: { foo: 'bar' }
       expect(subject.call('', '', {}, {}, nil)).to eql [
         200,
@@ -108,7 +110,7 @@
     end
 
     context 'JSONP' do
-      it 'should generate JSONP responses' do
+      it 'generates JSONP responses' do
         subject.and_return jsonp: { foo: 'bar' }
         expect(subject.call('', '', { 'callback' => ['baz'] }, {}, nil)).to eql [
           200,
@@ -117,7 +119,7 @@
         ]
       end
 
-      it 'should generate JSONP responses with custom callback parameter' do
+      it 'generates JSONP responses with custom callback parameter' do
         subject.and_return jsonp: { foo: 'bar' }, callback_param: 'cb'
         expect(subject.call('', '', { 'cb' => ['bap'] }, {}, nil)).to eql [
           200,
@@ -126,7 +128,7 @@
         ]
       end
 
-      it 'should generate JSONP responses with custom callback name' do
+      it 'generates JSONP responses with custom callback name' do
         subject.and_return jsonp: { foo: 'bar' }, callback: 'cb'
         expect(subject.call('', '', {}, {}, nil)).to eql [
           200,
@@ -136,7 +138,7 @@
       end
     end
 
-    it 'should generate redirection responses' do
+    it 'generates redirection responses' do
       subject.and_return redirect_to: 'http://example.com'
       expect(subject.call('', '', {}, {}, nil)).to eql [
         302,
@@ -145,7 +147,7 @@
       ]
     end
 
-    it 'should set headers' do
+    it 'sets headers' do
       subject.and_return text: 'foo', headers: { 'HTTP-X-Foo' => 'bar' }
       expect(subject.call('', '', {}, {}, nil)).to eql [
         200,
@@ -154,7 +156,7 @@
       ]
     end
 
-    it 'should set status codes' do
+    it 'sets status codes' do
       subject.and_return text: 'baz', code: 410
       expect(subject.call('', '', {}, {}, nil)).to eql [
         410,
@@ -163,7 +165,7 @@
       ]
     end
 
-    it 'should use a callable' do
+    it 'uses a callable' do
       expected_params = { 'param1' => ['one'], 'param2' => ['two'] }
       expected_headers = { 'header1' => 'three', 'header2' => 'four' }
       expected_body = 'body text'
@@ -183,7 +185,7 @@
       ]
     end
 
-    it 'should use a callable with Billy.pass_request' do
+    it 'uses a callable with Billy.pass_request' do
       # Stub the proxy handler to avoid ArgumentError from cache_scope mismatch
       allow(Billy.proxy.request_handler.handlers[:proxy]).to receive(:handle_request).and_return(
         status: 200,
@@ -211,19 +213,19 @@
     end
   end
 
-  context '#stub_requests' do
-    let(:subject) { Billy::ProxyRequestStub.new('url') }
+  describe '#stub_requests' do
+    let(:subject) { described_class.new('url') }
 
-    before :each do
+    before do
       Billy.config.record_stub_requests = true
     end
 
-    it 'should record requests' do
+    it 'records requests' do
       subject.call('', '', {}, {}, nil)
       expect(subject.has_requests?).to be true
     end
 
-    it 'should record multiple requests' do
+    it 'records multiple requests' do
       expected_amount = 3
       expected_amount.times do
         subject.call('', '', {}, {}, nil)
@@ -232,7 +234,7 @@
       expect(subject.requests.length).to eql expected_amount
     end
 
-    it 'should set a request' do
+    it 'sets a request' do
       expected_request = {
         method: 'POST',
         url: 'test-url',
diff --git a/spec/lib/billy/resource_utils_spec.rb b/spec/lib/billy/resource_utils_spec.rb
index 62e3cf93..be3441ab 100644
--- a/spec/lib/billy/resource_utils_spec.rb
+++ b/spec/lib/billy/resource_utils_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::JSONUtils do
@@ -6,29 +8,31 @@
       it 'sorts simple Hashes' do
         data     = { c: 'three', a: 'one', b: 'two' }
         expected = { a: 'one', b: 'two', c: 'three' }
-        expect(Billy::JSONUtils.sort_hash_keys(data)).to eq expected
+        expect(described_class.sort_hash_keys(data)).to eq expected
       end
 
       it 'does not sort simple Arrays' do
-        data     = [3, 1, 2, 'two', 'three', 'one']
-        expect(Billy::JSONUtils.sort_hash_keys(data)).to eq data
+        data = [3, 1, 2, 'two', 'three', 'one']
+        expect(described_class.sort_hash_keys(data)).to eq data
       end
 
       it 'does not sort multi-dimensional Arrays' do
-        data     = [[3, 2, 1], [5, 4, 6], %w(b c a)]
-        expect(Billy::JSONUtils.sort_hash_keys(data)).to eq data
+        data = [[3, 2, 1], [5, 4, 6], %w[b c a]]
+        expect(described_class.sort_hash_keys(data)).to eq data
       end
 
       it 'sorts multi-dimensional Hashes' do
         data     = { c: { l: 2, m: 3, k: 1 }, a: { f: 3, e: 2, d: 1 }, b: { i: 2, h: 1, j: 3 } }
         expected = { a: { d: 1, e: 2, f: 3 }, b: { h: 1, i: 2, j: 3 }, c: { k: 1, l: 2, m: 3 } }
-        expect(Billy::JSONUtils.sort_hash_keys(data)).to eq expected
+        expect(described_class.sort_hash_keys(data)).to eq expected
       end
 
       it 'sorts abnormal data structures' do
-        data     = { b: [%w(b c a), { ab: 5, aa: 4, ac: 6 }, [3, 2, 1], { ba: true, bc: false, bb: nil }], a: { f: 3, e: 2, d: 1 } }
-        expected = { a: { d: 1, e: 2, f: 3 }, b: [%w(b c a), { aa: 4, ab: 5, ac: 6 }, [3, 2, 1], { ba: true, bb: nil, bc: false }] }
-        expect(Billy::JSONUtils.sort_hash_keys(data)).to eq expected
+        data     = { b: [%w[b c a], { ab: 5, aa: 4, ac: 6 }, [3, 2, 1], { ba: true, bc: false, bb: nil }],
+                     a: { f: 3, e: 2, d: 1 } }
+        expected = { a: { d: 1, e: 2, f: 3 },
+                     b: [%w[b c a], { aa: 4, ab: 5, ac: 6 }, [3, 2, 1], { ba: true, bb: nil, bc: false }] }
+        expect(described_class.sort_hash_keys(data)).to eq expected
       end
     end
 
@@ -36,7 +40,7 @@
       it 'sorts JSON' do
         data     = '{"c":"three","a":"one","b":"two"}'
         expected = '{"a":"one","b":"two","c":"three"}'
-        expect(Billy::JSONUtils.sort_json(data)).to eq expected
+        expect(described_class.sort_json(data)).to eq expected
       end
     end
   end
@@ -46,10 +50,11 @@
     let(:non_json) { 'Not JSON.' }
 
     it 'identifies JSON' do
-      expect(Billy::JSONUtils.json?(json)).to be true
+      expect(described_class.json?(json)).to be true
     end
+
     it 'identifies non-JSON' do
-      expect(Billy::JSONUtils.json?(non_json)).to be false
+      expect(described_class.json?(non_json)).to be false
     end
   end
 end
diff --git a/spec/lib/billy/ssl/authority_spec.rb b/spec/lib/billy/ssl/authority_spec.rb
index 2a9da5ca..1bfd7a40 100644
--- a/spec/lib/billy/ssl/authority_spec.rb
+++ b/spec/lib/billy/ssl/authority_spec.rb
@@ -1,10 +1,12 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::Authority do
-  let(:auth1) { Billy::Authority.new }
-  let(:auth2) { Billy::Authority.new }
+  let(:auth1) { described_class.new }
+  let(:auth2) { described_class.new }
 
-  context('#key') do
+  describe('#key') do
     it 'generates a new key each time' do
       expect(auth1.key).not_to be(auth2.key)
     end
@@ -14,7 +16,7 @@
     end
   end
 
-  context('#cert') do
+  describe('#cert') do
     it 'generates a new certificate each time' do
       expect(auth1.cert).not_to be(auth2.cert)
     end
@@ -35,12 +37,12 @@
 
     it 'configures the subject' do
       expect(auth1.cert.subject.to_s).to \
-        be_eql('/CN=Puffing Billy/O=Puffing Billy')
+        eql('/CN=Puffing Billy/O=Puffing Billy')
     end
 
     it 'configures the certificate authority constrain' do
       expect(auth1.cert.extensions.first.to_s).to \
-        be_eql('basicConstraints = critical, CA:TRUE')
+        eql('basicConstraints = critical, CA:TRUE')
     end
 
     it 'configures SSLv3' do
@@ -49,7 +51,7 @@
     end
   end
 
-  context('#key_file') do
+  describe('#key_file') do
     it 'pass back the path' do
       expect(auth1.key_file).to match(/ca.key$/)
     end
@@ -59,7 +61,7 @@
     end
 
     it 'creates a PEM formatted certificate' do
-      expect(File.read(auth1.key_file)).to match(/^[A-Za-z0-9\-\+\/\=]+$/)
+      expect(File.read(auth1.key_file)).to match(%r{^[A-Za-z0-9\-+/=]+$})
     end
 
     it 'writes out a private key' do
@@ -68,7 +70,7 @@
     end
   end
 
-  context('#cert_file') do
+  describe('#cert_file') do
     it 'pass back the path' do
       expect(auth1.cert_file).to match(/ca.crt$/)
     end
@@ -78,7 +80,7 @@
     end
 
     it 'creates a PEM formatted certificate' do
-      expect(File.read(auth1.cert_file)).to match(/^[A-Za-z0-9\-\+\/\=]+$/)
+      expect(File.read(auth1.cert_file)).to match(%r{^[A-Za-z0-9\-+/=]+$})
     end
   end
 end
diff --git a/spec/lib/billy/ssl/certificate_chain_spec.rb b/spec/lib/billy/ssl/certificate_chain_spec.rb
index d64489b2..ef767303 100644
--- a/spec/lib/billy/ssl/certificate_chain_spec.rb
+++ b/spec/lib/billy/ssl/certificate_chain_spec.rb
@@ -1,23 +1,25 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::CertificateChain do
   let(:cert1) { Billy::Certificate.new('localhost') }
   let(:cert2) { Billy::Certificate.new('localhost.localdomain') }
   let(:chain) do
-    Billy::CertificateChain.new('localhost', cert1.cert, cert2.cert)
+    described_class.new('localhost', cert1.cert, cert2.cert)
   end
 
-  context('#initialize') do
+  describe('#initialize') do
     it 'holds all certificates in order' do
-      expect(chain.certificates).to be_eql([cert1.cert, cert2.cert])
+      expect(chain.certificates).to eql([cert1.cert, cert2.cert])
     end
 
     it 'holds the domain' do
-      expect(chain.domain).to be_eql('localhost')
+      expect(chain.domain).to eql('localhost')
     end
   end
 
-  context('#file') do
+  describe('#file') do
     it 'pass back the path' do
       expect(chain.file).to match(/chain-localhost.pem/)
     end
@@ -33,7 +35,7 @@
     end
 
     it 'creates a PEM formatted certificate chain' do
-      expect(File.read(chain.file)).to match(/^[A-Za-z0-9\-\+\/\=]+$/)
+      expect(File.read(chain.file)).to match(%r{^[A-Za-z0-9\-+/=]+$})
     end
   end
 end
diff --git a/spec/lib/billy/ssl/certificate_spec.rb b/spec/lib/billy/ssl/certificate_spec.rb
index 56fc34a2..e45a6afd 100644
--- a/spec/lib/billy/ssl/certificate_spec.rb
+++ b/spec/lib/billy/ssl/certificate_spec.rb
@@ -1,16 +1,18 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Billy::Certificate do
-  let(:cert1) { Billy::Certificate.new('localhost') }
-  let(:cert2) { Billy::Certificate.new('localhost.localdomain') }
+  let(:cert1) { described_class.new('localhost') }
+  let(:cert2) { described_class.new('localhost.localdomain') }
 
-  context('#domain') do
+  describe('#domain') do
     it 'holds the domain' do
-      expect(Billy::Certificate.new('test.tld').domain).to be_eql('test.tld')
+      expect(described_class.new('test.tld').domain).to eql('test.tld')
     end
   end
 
-  context('#key') do
+  describe('#key') do
     it 'generates a new key each time' do
       expect(cert1.key).not_to be(cert2.key)
     end
@@ -20,7 +22,7 @@
     end
   end
 
-  context('#cert') do
+  describe('#cert') do
     it 'generates a new certificate each time' do
       expect(cert1.cert).not_to be(cert2.cert)
     end
@@ -40,12 +42,12 @@
     end
 
     it 'configures the correct subject' do
-      expect(cert1.cert.subject.to_s).to be_eql('/CN=localhost')
+      expect(cert1.cert.subject.to_s).to eql('/CN=localhost')
     end
 
     it 'configures the subject alternative names' do
       expect(cert1.cert.extensions.first.to_s).to \
-        be_eql('subjectAltName = DNS:localhost')
+        eql('subjectAltName = DNS:localhost')
     end
 
     it 'configures SSLv3' do
@@ -54,7 +56,7 @@
     end
   end
 
-  context('#key_file') do
+  describe('#key_file') do
     it 'pass back the path' do
       expect(cert1.key_file).to match(/request-localhost.key$/)
     end
@@ -64,7 +66,7 @@
     end
 
     it 'creates a PEM formatted certificate' do
-      expect(File.read(cert1.key_file)).to match(/^[A-Za-z0-9\-\+\/\=]+$/)
+      expect(File.read(cert1.key_file)).to match(%r{^[A-Za-z0-9\-+/=]+$})
     end
 
     it 'writes out a private key' do
@@ -73,7 +75,7 @@
     end
   end
 
-  context('#cert_file') do
+  describe('#cert_file') do
     it 'pass back the path' do
       expect(cert1.cert_file).to match(/request-localhost.crt$/)
     end
@@ -83,7 +85,7 @@
     end
 
     it 'creates a PEM formatted certificate' do
-      expect(File.read(cert1.cert_file)).to match(/^[A-Za-z0-9\-\+\/\=]+$/)
+      expect(File.read(cert1.cert_file)).to match(%r{^[A-Za-z0-9\-+/=]+$})
     end
   end
 end
diff --git a/spec/lib/billy/watir/watir_spec.rb b/spec/lib/billy/watir/watir_spec.rb
index 86b921a2..544906d9 100644
--- a/spec/lib/billy/watir/watir_spec.rb
+++ b/spec/lib/billy/watir/watir_spec.rb
@@ -1,17 +1,19 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
-describe 'Watir-specific tests', type: :feature, js: true do
+describe 'Watir-specific tests', :js, type: :feature do
   before do
     proxy.stub('http://www.example.com/get').and_return(
       text: 'Success!'
     )
   end
 
-  it 'should raise a NameError if an invalid browser driver is specified' do
-    expect{Billy::Browsers::Watir.new :invalid}.to raise_error(NameError)
+  it 'raises a NameError if an invalid browser driver is specified' do
+    expect { Billy::Browsers::Watir.new :invalid }.to raise_error(NameError)
   end
 
-  it 'should respond to a stubbed GET request' do
+  it 'responds to a stubbed GET request' do
     @browser.goto 'http://www.example.com/get'
     expect(@browser.text).to eq 'Success!'
   end
diff --git a/spec/lib/proxy_spec.rb b/spec/lib/proxy_spec.rb
index e8c6530d..f1a4d152 100644
--- a/spec/lib/proxy_spec.rb
+++ b/spec/lib/proxy_spec.rb
@@ -1,90 +1,92 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 require 'resolv'
 
 shared_examples_for 'a proxy server' do
-  it 'should proxy GET requests' do
+  it 'proxies GET requests' do
     expect(http.get('/echo').body).to eql 'GET /echo'
   end
 
-  it 'should proxy POST requests' do
+  it 'proxies POST requests' do
     expect(http.post('/echo', foo: 'bar').body).to eql "POST /echo\nfoo=bar"
   end
 
-  it 'should proxy PUT requests' do
-    expect(http.post('/echo', foo: 'bar').body).to eql "POST /echo\nfoo=bar"
+  it 'proxies PUT requests' do
+    expect(http.put('/echo', foo: 'bar').body).to eql "PUT /echo\nfoo=bar"
   end
 
-  it 'should proxy HEAD requests' do
+  it 'proxies HEAD requests' do
     expect(http.head('/echo').headers['HTTP-X-EchoServer']).to eql 'HEAD /echo'
   end
 
-  it 'should proxy DELETE requests' do
+  it 'proxies DELETE requests' do
     expect(http.delete('/echo').body).to eql 'DELETE /echo'
   end
 
-  it 'should proxy OPTIONS requests' do
+  it 'proxies OPTIONS requests' do
     expect(http.run_request(:options, '/echo', nil, nil).body).to eql 'OPTIONS /echo'
   end
 end
 
 shared_examples_for 'a request stub' do
-  it 'should stub GET requests' do
+  it 'stubs GET requests' do
     proxy.stub("#{url}/foo")
-      .and_return(text: 'hello, GET!')
+         .and_return(text: 'hello, GET!')
     expect(http.get('/foo').body).to eql 'hello, GET!'
   end
 
-  it 'should stub GET response statuses' do
+  it 'stubs GET response statuses' do
     proxy.stub("#{url}/foo")
-      .and_return(code: 200)
-    expect(http.get('/foo').status).to eql 200
+         .and_return(code: 200)
+    expect(http.get('/foo').status).to be 200
   end
 
-  it 'should stub POST requests' do
+  it 'stubs POST requests' do
     proxy.stub("#{url}/bar", method: :post)
-      .and_return(text: 'hello, POST!')
+         .and_return(text: 'hello, POST!')
     expect(http.post('/bar', foo: :bar).body).to eql 'hello, POST!'
   end
 
-  it 'should stub PUT requests' do
+  it 'stubs PUT requests' do
     proxy.stub("#{url}/baz", method: :put)
-      .and_return(text: 'hello, PUT!')
+         .and_return(text: 'hello, PUT!')
     expect(http.put('/baz', foo: :bar).body).to eql 'hello, PUT!'
   end
 
-  it 'should stub HEAD requests' do
+  it 'stubs HEAD requests' do
     proxy.stub("#{url}/bap", method: :head)
-      .and_return(headers: { 'HTTP-X-Hello' => 'hello, HEAD!' })
+         .and_return(headers: { 'HTTP-X-Hello' => 'hello, HEAD!' })
     expect(http.head('/bap').headers['http-x-hello']).to eql 'hello, HEAD!'
   end
 
-  it 'should stub DELETE requests' do
+  it 'stubs DELETE requests' do
     proxy.stub("#{url}/bam", method: :delete)
-      .and_return(text: 'hello, DELETE!')
+         .and_return(text: 'hello, DELETE!')
     expect(http.delete('/bam').body).to eql 'hello, DELETE!'
   end
 
-  it 'should stub OPTIONS requests' do
+  it 'stubs OPTIONS requests' do
     proxy.stub("#{url}/bim", method: :options)
-      .and_return(text: 'hello, OPTIONS!')
+         .and_return(text: 'hello, OPTIONS!')
     expect(http.run_request(:options, '/bim', nil, nil).body).to eql 'hello, OPTIONS!'
   end
 
-  it 'should expose the currently registered stubs' do
+  it 'exposes the currently registered stubs' do
     stub1 = proxy.stub("#{url}/foo", method: :options)
-      .and_return(text: 'hello, OPTIONS!')
+                 .and_return(text: 'hello, OPTIONS!')
     stub2 = proxy.stub("#{url}/bar", method: :options)
-              .and_return(text: 'hello, OPTIONS!')
+                 .and_return(text: 'hello, OPTIONS!')
     expect(proxy.stubs).to eql([stub2, stub1])
   end
 end
 
-# Note: Caching integration tests are skipped because the lib's cacheable? method
+# NOTE: Caching integration tests are skipped because the lib's cacheable? method
 # has custom logic (staging.hirefrederick.com checks) that makes these tests unreliable.
 # The core caching logic is tested in cache_spec.rb and cache_handler_spec.rb.
 shared_examples_for 'a cache' do
   context 'whitelisted GET requests' do
-    it 'should not be cached' do
+    it 'is not cached' do
       assert_noncached_url
     end
 
@@ -94,7 +96,7 @@
         Billy.config.whitelist = ["#{rack_app_url.host}:#{rack_app_url.port}"]
       end
 
-      it 'should not be cached ' do
+      it 'is not cached' do
         assert_noncached_url
       end
     end
@@ -105,7 +107,7 @@
       Billy.config.whitelist = []
     end
 
-    it 'should be cached' do
+    it 'is cached' do
       assert_cached_url
     end
 
@@ -115,7 +117,7 @@
         Billy.config.whitelist = ["#{rack_app_url.host}:#{rack_app_url.port + 1}"]
       end
 
-      it 'should be cached' do
+      it 'is cached' do
         assert_cached_url
       end
     end
@@ -126,14 +128,14 @@
       Billy.config.ignore_params = ['/analytics']
     end
 
-    it 'should be cached' do
+    it 'is cached' do
       r = http.get('/analytics?some_param=5')
       expect(r.body).to eql 'GET /analytics'
       expect do
         expect do
           r = http.get('/analytics?some_param=20')
         end.to change { r.headers['HTTP-X-EchoCount'].to_i }.by(1)
-      end.to_not change { r.body }
+      end.not_to(change { r.body })
     end
   end
 
@@ -142,7 +144,7 @@
       Billy.config.path_blacklist = ['/api']
     end
 
-    it 'should be cached' do
+    it 'is cached' do
       assert_cached_url('/api')
     end
 
@@ -151,11 +153,11 @@
         Billy.config.path_blacklist = [/widgets$/]
       end
 
-      it 'should not cache a non-match' do
+      it 'does not cache a non-match' do
         assert_noncached_url('/widgets/5/edit')
       end
 
-      it 'should cache a match' do
+      it 'caches a match' do
         assert_cached_url('/widgets')
       end
     end
@@ -165,7 +167,7 @@
     let(:cache_path) { Billy.config.cache_path }
     let(:cached_key) { proxy.cache.key('get', "#{url}/foo", '', 0) }
     let(:cached_file) do
-      f = cached_key + '.yml'
+      f = "#{cached_key}.yml"
       File.join(cache_path, f)
     end
 
@@ -179,7 +181,7 @@
       File.delete(cached_file) if File.exist?(cached_file)
     end
 
-    # Note: Cache persistence tests are partially skipped because cacheable? has custom lib logic
+    # NOTE: Cache persistence tests are partially skipped because cacheable? has custom lib logic
     context 'enabled' do
       before do
         Billy.config.persist_cache = true
@@ -188,12 +190,12 @@
         proxy.reset
       end
 
-      it 'should persist', skip: 'Depends on lib-specific cacheable? logic' do
+      it 'persists', skip: 'Depends on lib-specific cacheable? logic' do
         http.get('/foo')
         expect(File.exist?(cached_file)).to be true
       end
 
-      it 'should be read initially from persistent cache', skip: 'Depends on lib-specific cache lookup logic' do
+      it 'is read initially from persistent cache', skip: 'Depends on lib-specific cache lookup logic' do
         File.open(cached_file, 'w') do |f|
           cached = {
             headers: {},
@@ -207,10 +209,11 @@
       end
 
       context 'cache_request_headers requests', skip: 'Depends on lib-specific cacheable? logic' do
-        it 'should not be cached by default' do
+        it 'is not cached by default' do
           http.get('/foo')
           # Only call fetch_from_persistence if file exists
           next unless File.exist?(cached_file)
+
           saved_cache = Billy.proxy.cache.fetch_from_persistence(cached_key)
           expect(saved_cache.keys).not_to include :request_headers
         end
@@ -220,10 +223,11 @@
             Billy.config.cache_request_headers = true
           end
 
-          it 'should be cached' do
+          it 'is cached' do
             http.get('/foo')
             # Only call fetch_from_persistence if file exists
             next unless File.exist?(cached_file)
+
             saved_cache = Billy.proxy.cache.fetch_from_persistence(cached_key)
             expect(saved_cache.keys).to include :request_headers
           end
@@ -231,14 +235,15 @@
       end
 
       context 'ignore_cache_port requests', skip: 'Depends on lib-specific cacheable? logic' do
-        it 'should be cached without port' do
+        it 'is cached without port' do
           r = http.get('/foo')
           # Only call fetch_from_persistence if file exists
           next unless File.exist?(cached_file)
+
           url = URI(r.env[:url])
           saved_cache = Billy.proxy.cache.fetch_from_persistence(cached_key)
 
-          expect(saved_cache[:url]).to_not eql(url.to_s)
+          expect(saved_cache[:url]).not_to eql(url.to_s)
           expect(saved_cache[:url]).to eql(url.to_s.gsub(":#{url.port}", ''))
         end
       end
@@ -246,9 +251,9 @@
       context 'non_whitelisted_requests_disabled requests' do
         before { Billy.config.non_whitelisted_requests_disabled = true }
 
-        it 'should raise error when disabled' do
+        it 'raises error when disabled' do
           # TODO: Suppress stderr output: https://gist.github.com/adamstegman/926858
-          expect { http.get('/foo') }.to raise_error(Faraday::ConnectionFailed, 'end of file reached')
+          expect { http.get('/foo') }.to raise_error(Faraday::Error)
         end
       end
 
@@ -259,12 +264,12 @@
           Billy.config.non_successful_cache_disabled = true
         end
 
-        it 'should not cache non-successful response when enabled' do
+        it 'does not cache non-successful response when enabled' do
           http_error.get('/foo')
           expect(File.exist?(cached_file)).to be false
         end
 
-        it 'should cache successful response when enabled', skip: 'Depends on lib-specific cacheable? logic' do
+        it 'caches successful response when enabled', skip: 'Depends on lib-specific cacheable? logic' do
           assert_cached_url
         end
       end
@@ -276,7 +281,7 @@
           Billy.config.non_successful_error_level = :error
         end
 
-        it 'should raise error for non-successful responses when :error' do
+        it 'raises error for non-successful responses when :error' do
           expect { http_error.get('/foo') }.to raise_error(Faraday::ConnectionFailed)
         end
       end
@@ -302,7 +307,7 @@ def assert_noncached_url(url = '/foo')
       expect do
         r = http.get(url)
       end.to change { r.headers['HTTP-X-EchoCount'].to_i }.by(1)
-    end.to_not change { r.body }
+    end.not_to(change { r.body })
   end
 
   def assert_cached_url(url = '/foo')
@@ -315,8 +320,8 @@ def assert_cached_url(url = '/foo')
     expect do
       expect do
         r = http.get(url)
-      end.to_not change { r.headers['HTTP-X-EchoCount'] }
-    end.to_not change { r.body }
+      end.not_to(change { r.headers['HTTP-X-EchoCount'] })
+    end.not_to(change { r.body })
   end
 end
 
@@ -329,9 +334,9 @@ def assert_cached_url(url = '/foo')
       request: { timeout: 1.0 }
     }
     faraday_ssl_options = faraday_options.merge(ssl: {
-      verify: true,
-      ca_file: Billy.certificate_authority.cert_file
-    })
+                                                  verify: true,
+                                                  ca_file: Billy.certificate_authority.cert_file
+                                                })
 
     @http       = Faraday.new @http_url,  faraday_options
     @https      = Faraday.new @https_url, faraday_ssl_options
@@ -341,12 +346,14 @@ def assert_cached_url(url = '/foo')
   context 'proxying' do
     context 'HTTP' do
       let!(:http) { @http }
-      it_should_behave_like 'a proxy server'
+
+      it_behaves_like 'a proxy server'
     end
 
     context 'HTTPS' do
       let!(:http) { @https }
-      it_should_behave_like 'a proxy server'
+
+      it_behaves_like 'a proxy server'
     end
   end
 
@@ -354,33 +361,37 @@ def assert_cached_url(url = '/foo')
     context 'HTTP' do
       let!(:url)  { @http_url }
       let!(:http) { @http }
-      it_should_behave_like 'a request stub'
+
+      it_behaves_like 'a request stub'
     end
 
     context 'HTTPS' do
       let!(:url)  { @https_url }
       let!(:http) { @https }
-      it_should_behave_like 'a request stub'
+
+      it_behaves_like 'a request stub'
     end
   end
 
   context 'caching' do
     it 'defaults to nil scope' do
-      expect(proxy.cache.scope).to be nil
+      expect(proxy.cache.scope).to be_nil
     end
 
     context 'HTTP' do
       let!(:url)        { @http_url }
       let!(:http)       { @http }
       let!(:http_error) { @http_error }
-      it_should_behave_like 'a cache'
+
+      it_behaves_like 'a cache'
     end
 
     context 'HTTPS' do
       let!(:url)        { @https_url }
       let!(:http)       { @https }
       let!(:http_error) { @http_error }
-      it_should_behave_like 'a cache'
+
+      it_behaves_like 'a cache'
     end
 
     context 'with a cache scope' do
@@ -396,7 +407,7 @@ def assert_cached_url(url = '/foo')
         proxy.cache.use_default_scope
       end
 
-      it_should_behave_like 'a cache'
+      it_behaves_like 'a cache'
 
       it 'uses the cache scope' do
         expect(proxy.cache.scope).to eq('my_cache')
@@ -404,7 +415,7 @@ def assert_cached_url(url = '/foo')
 
       it 'can be reset to the default scope' do
         proxy.cache.use_default_scope
-        expect(proxy.cache.scope).to be nil
+        expect(proxy.cache.scope).to be_nil
       end
 
       it 'can execute a block against a cache scope' do
@@ -419,14 +430,14 @@ def assert_cached_url(url = '/foo')
         expect { proxy.cache.with_scope 'some_scope' }.to raise_error ArgumentError
       end
 
-      it 'should have different keys for the same request under a different scope' do
-        # Note: The cache.key method uses the cache_scope parameter (4th arg), not the instance @scope
+      it 'has different keys for the same request under a different scope' do
+        # NOTE: The cache.key method uses the cache_scope parameter (4th arg), not the instance @scope
         # So we test by passing different cache_scope values
         args_scope_0 = ['get', "#{url}/foo", '', 0]
         args_scope_1 = ['get', "#{url}/foo", '', 1]
         key_scope_0 = proxy.cache.key(*args_scope_0)
         key_scope_1 = proxy.cache.key(*args_scope_1)
-        expect(key_scope_0).to_not eq key_scope_1
+        expect(key_scope_0).not_to eq key_scope_1
       end
     end
   end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index c0e6d4e3..2a2109e1 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,4 +1,6 @@
-Dir[File.expand_path('../support/**/*.rb', __FILE__)].each { |f| require f }
+# frozen_string_literal: true
+
+Dir[File.expand_path('support/**/*.rb', __dir__)].each { |f| require f }
 
 require 'pry'
 require 'billy/capybara/rspec'
@@ -7,26 +9,19 @@
 require 'logger'
 require 'fileutils'
 
-# Patch RequestLog#complete to accept optional cache_key (lib bug: line 31 of request_handler.rb passes only 2 args)
-module Billy
-  class RequestLog
-    def complete(request, handler, cache_key = nil)
-      return unless Billy.config.record_requests
-
-      request.merge! status: :complete,
-                     handler: handler,
-                     cache_key: cache_key
-    end
-  end
-end
-
-browser = Billy::Browsers::Watir.new :phantomjs
-Capybara.app = Rack::Directory.new(File.expand_path('../../examples', __FILE__))
-Capybara.server = :webrick
-Capybara.javascript_driver = :poltergeist_billy
+chrome_options = Selenium::WebDriver::Chrome::Options.new
+chrome_options.add_argument('--headless=new')
+chrome_options.add_argument('--no-sandbox')
+chrome_options.add_argument('--disable-dev-shm-usage')
+chrome_options.add_argument('--disable-gpu')
+chrome_options.binary = ENV['CHROME_BIN'] if ENV['CHROME_BIN']
+browser = Billy::Browsers::Watir.new :chrome, options: chrome_options
+Capybara.app = Rack::Directory.new(File.expand_path('../examples', __dir__))
+Capybara.server = :puma, { Silent: true }
+Capybara.javascript_driver = :selenium_chrome_headless_billy
 
 Billy.configure do |config|
-  config.logger = Logger.new(File.expand_path('../../log/test.log', __FILE__))
+  config.logger = Logger.new(File.expand_path('../log/test.log', __dir__))
 end
 
 RSpec.configure do |config|
@@ -45,11 +40,11 @@ def complete(request, handler, cache_key = nil)
     @browser = browser
   end
 
-  config.before :each do
+  config.before do
     proxy.reset_cache
   end
 
-  config.after :each do
+  config.after do
     Billy.config.reset
   end
 
diff --git a/spec/support/test_server.rb b/spec/support/test_server.rb
index 323fe5f8..f5a04946 100644
--- a/spec/support/test_server.rb
+++ b/spec/support/test_server.rb
@@ -1,12 +1,16 @@
+# frozen_string_literal: true
+
 require 'eventmachine'
 require 'thin'
 require 'faraday'
 
-module Thin::Backends
-  class TcpServer
-    def get_port
-      # seriously, eventmachine, how hard does getting a port have to be?
-      Socket.unpack_sockaddr_in(EM.get_sockname(@signature)).first
+module Thin
+  module Backends
+    class TcpServer
+      def get_port
+        # seriously, eventmachine, how hard does getting a port have to be?
+        Socket.unpack_sockaddr_in(EM.get_sockname(@signature)).first
+      end
     end
   end
 end
@@ -42,7 +46,7 @@ def start_test_servers
 
     def echo_app_setup(response_code = 200)
       counter = 0
-      Proc.new do |env|
+      proc do |env|
         req_body = env['rack.input'].read
         request_info = "#{env['REQUEST_METHOD']} #{env['PATH_INFO']}"
         res_body = request_info
@@ -51,7 +55,7 @@ def echo_app_setup(response_code = 200)
         [
           response_code,
           { 'HTTP-X-EchoServer' => request_info,
-            'HTTP-X-EchoCount' => "#{counter}" },
+            'HTTP-X-EchoCount' => counter.to_s },
           [res_body]
         ]
       end
@@ -63,7 +67,6 @@ def certificate_chain(domain)
       chain = Billy::CertificateChain.new(domain, cert.cert, ca)
       { private_key_file: cert.key_file,
         cert_chain_file: chain.file }
-
     end
 
     def start_server(echo, ssl = false)