Rewind rack.input in Base before reading request body for Rack 3 support

[cilim]

Rack 3 support

Resolves: #72

Summary

Fixes missing JSON, plain text, and XML requestBody examples in generated docs, and a NoMethodError on bodyless requests, when running the dox formatter against request specs on Rails apps using Rack 3.

Problem

Rack 3 dropped the implicit rewind on Rack::Request#body. Dox::Formatters::Multipart was fixed in v3.0.1 (#71), but Json, Plain, and Xml still inherit from Formatters::Base, which reads the request body without rewinding first.

By the time the formatter runs, Rails has already consumed the body during request processing, so http_env.body.read returns "". For JSON requests this silently omits requestBody examples from the generated spec. For bodyless requests, Rack 3 returns nil instead of StringIO(""), which causes Formatters::Plain to raise NoMethodError on body.encoding.

Test plan

• bundle exec rspec spec/formatters/
• bundle exec rspec