Add mismatched sequence size check

lib/active_record_doctor.rb

@@ -20,6 +20,7 @@
 require "active_record_doctor/detectors/incorrect_dependent_option"
 require "active_record_doctor/detectors/short_primary_key_type"
 require "active_record_doctor/detectors/mismatched_foreign_key_type"
+require "active_record_doctor/detectors/mismatched_sequence_type"
 require "active_record_doctor/detectors/table_without_primary_key"
 require "active_record_doctor/detectors/table_without_timestamps"
 require "active_record_doctor/errors"

lib/active_record_doctor/config/default.rb

@@ -34,6 +34,10 @@
     ignore_tables: [],
     ignore_columns: []
 
+  detector :mismatched_sequence_type,
+    enabled: true,
+    ignore_tables: []
+
   detector :missing_foreign_keys,
     enabled: true,
     ignore_models: [],

test/active_record_doctor/detectors/mismatched_sequence_type_test.rb

@@ -0,0 +1,147 @@
+# frozen_string_literal: true
+
+class ActiveRecordDoctor::Detectors::MismatchedSequenceTypeTest < Minitest::Test
+  def test_non_postgresql_generates_no_errors
+    skip if postgresql?
+
+    Context.create_table(:companies, id: :integer)
+    refute_problems
+  end
+
+  def test_matching_integer_primary_key_and_sequence_is_not_reported
+    skip unless postgresql?
+
+    Context.create_table(:companies, id: :integer)
+    refute_problems
+  end
+
+  def test_matching_bigint_primary_key_and_sequence_is_not_reported
+    skip unless postgresql?
+
+    Context.create_table(:companies, id: :bigint)
+    refute_problems
+  end
+
+  def test_bigint_column_with_integer_sequence_is_reported
+    skip unless postgresql?
+
+    Context.create_table(:companies, id: :integer)
+    # Widen the column without changing the sequence so the types diverge.
+    @connection.execute("ALTER TABLE companies ALTER COLUMN id TYPE bigint")
+
+    sequence = fetch_sequence("companies", "id")
+    assert sequence, "Expected a sequence to exist for companies.id"
+
+    assert_problems(<<~OUTPUT)
+      the sequence #{sequence} has type integer but companies.id is bigint - change the sequence type to bigint
+    OUTPUT
+  end
+
+  def test_bigint_column_with_smallint_sequence_is_reported
+    skip unless postgresql?
+
+    # Create with integer (gets a sequence), downgrade sequence to smallint,
+    # then widen the column to bigint — leaving a too-small sequence behind.
+    Context.create_table(:companies, id: :integer)
+    sequence = fetch_sequence("companies", "id")
+    assert sequence, "Expected a sequence to exist for companies.id"
+    @connection.execute("ALTER SEQUENCE #{sequence} AS smallint MAXVALUE 32767 RESTART 1")
+    @connection.execute("ALTER TABLE companies ALTER COLUMN id TYPE bigint")
+
+    assert_problems(<<~OUTPUT)
+      the sequence #{sequence} has type smallint but companies.id is bigint - change the sequence type to bigint
+    OUTPUT
+  end
+
+  def test_integer_column_with_smallint_sequence_is_reported
+    skip unless postgresql?
+
+    # Create with integer (gets a sequence), then downgrade the sequence type
+    # to smallint — the column remains integer but the sequence is now too small.
+    Context.create_table(:companies, id: :integer)
+    sequence = fetch_sequence("companies", "id")
+    assert sequence, "Expected a sequence to exist for companies.id"
+    @connection.execute("ALTER SEQUENCE #{sequence} AS smallint MAXVALUE 32767 RESTART 1")
+
+    assert_problems(<<~OUTPUT)
+      the sequence #{sequence} has type smallint but companies.id is integer - change the sequence type to integer
+    OUTPUT
+  end
+
+  def test_uuid_primary_key_is_not_reported
+    skip unless postgresql?
+
+    require_uuid_column_type!
+
+    Context.create_table(:companies, id: :uuid)
+    refute_problems
+  end
+
+  def test_no_primary_key_is_not_reported
+    skip unless postgresql?
+
+    Context.create_table(:companies, id: false) do |t|
+      t.string :name, null: false
+    end
+
+    refute_problems
+  end
+
+  def test_config_ignore_tables
+    skip unless postgresql?
+
+    Context.create_table(:companies, id: :integer)
+    @connection.execute("ALTER TABLE companies ALTER COLUMN id TYPE bigint")
+
+    config_file(<<-CONFIG)
+      ActiveRecordDoctor.configure do |config|
+        config.detector :mismatched_sequence_type,
+          ignore_tables: ["companies"]
+      end
+    CONFIG
+
+    refute_problems
+  end
+
+  def test_global_ignore_tables
+    skip unless postgresql?
+
+    Context.create_table(:companies, id: :integer)
+    @connection.execute("ALTER TABLE companies ALTER COLUMN id TYPE bigint")
+
+    config_file(<<-CONFIG)
+      ActiveRecordDoctor.configure do |config|
+        config.global :ignore_tables, ["companies"]
+      end
+    CONFIG
+
+    refute_problems
+  end
+
+  private
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+    super
+  end
+
+  def fetch_sequence(table, column)
+    @connection.select_value(<<~SQL)
+      SELECT n.nspname || '.' || seq.relname
+      FROM pg_class seq
+      JOIN pg_namespace n ON n.oid = seq.relnamespace
+      JOIN pg_depend dep
+        ON dep.objid = seq.oid
+       AND dep.classid = 'pg_class'::regclass
+       AND dep.refobjid = #{@connection.quote(table)}::regclass
+       AND dep.refobjsubid = (
+             SELECT attnum FROM pg_attribute
+             WHERE attrelid = #{@connection.quote(table)}::regclass
+               AND attname = #{@connection.quote(column)}
+           )
+       AND dep.deptype IN ('a', 'i')
+      WHERE seq.relkind = 'S'
+      LIMIT 1
+    SQL
+  end
+end