Merge pull request #1383 from koic/intro_migrated_schema_version

Introduce `AllCops: MigratedSchemaVersion` config

Author: koic

README.md

@@ -83,6 +83,22 @@ gems.locked file to find the version of Rails that has been bound to the
 application. If neither of those files exist, RuboCop will use Rails 5.0
 as the default.
 
+### `AllCops: MigratedSchemaVersion`
+
+By specifying the `MigratedSchemaVersion` option, migration files that have already been run can be ignored.
+When `MigratedSchemaVersion: '20241225000000'` is set, migration files lower than or equal to '20241225000000' will be ignored.
+For example, to ignore db/migrate/20241225000000_create_articles.rb and earlier migrations you would configure it the following way:
+
+```yaml
+AllCops
+  MigratedSchemaVersion: '20241225000000'
+```
+
+This prevents inspecting schema settings for already applied migration files.
+Changing already applied migrations should be avoided because it can lead to the schema getting out of sync
+between your local copy and what it actually is in production, depending on when `bin/rails db:migrate` was executed.
+If you want to modify your schema to comply with the cops, you should instead create new migrations.
+
 ## Rails configuration tip
 
 In Rails 6.1+, add the following `config.generators.after_generate` setting to

changelog/new_intro_migrated_schema_version.md

@@ -0,0 +1 @@
+* [#1383](https://github.com/rubocop/rubocop-rails/pull/1383): Introduce `AllCops: MigratedSchemaVersion` config. ([@koic][])

config/default.yml

@@ -25,6 +25,10 @@ AllCops:
   # application. If neither of those files exist, RuboCop will use Rails 5.0
   # as the default.
   TargetRailsVersion: ~
+  # By specifying `MigratedSchemaVersion` option, migration files that have been migrated can be ignored.
+  # When `MigratedSchemaVersion: '20241231000000'` is set. Migration files lower than or equal to '20250101000000' will be ignored.
+  # For example, this is the timestamp in db/migrate/20250101000000_create_articles.rb.
+  MigratedSchemaVersion: ~
 
 Lint/NumberConversion:
   # Add Rails' duration methods to the ignore list for `Lint/NumberConversion`

docs/modules/ROOT/pages/usage.adoc

@@ -52,6 +52,23 @@ gems.locked file to find the version of Rails that has been bound to the
 application. If neither of those files exist, RuboCop will use Rails 5.0
 as the default.
 
+=== `AllCops: MigratedSchemaVersion`
+
+By specifying the `MigratedSchemaVersion` option, migration files that have already been run can be ignored.
+When `MigratedSchemaVersion: '20241225000000'` is set, migration files lower than or equal to '20241225000000' will be ignored.
+For example, to ignore db/migrate/20241225000000_create_articles.rb and earlier migrations you would configure it the following way:
+
+[source,yaml]
+----
+AllCops
+  MigratedSchemaVersion: '20241225000000'
+----
+
+This prevents inspecting schema settings for already applied migration files.
+Changing already applied migrations should be avoided because it can lead to the schema getting out of sync
+between your local copy and what it actually is in production, depending on when `bin/rails db:migrate` was executed.
+If you want to modify your schema to comply with the cops, you should instead create new migrations.
+
 == Rails configuration tip
 
 In Rails 6.1+, add the following `config.generators.after_generate` setting to

lib/rubocop/cop/mixin/migrations_helper.rb

@@ -21,6 +21,35 @@ def in_migration?(node)
           migration_class?(class_node)
         end
       end
+
+      # rubocop:disable Style/DocumentDynamicEvalDefinition
+      %i[on_send on_csend on_block on_numblock on_class].each do |method|
+        class_eval(<<~RUBY, __FILE__, __LINE__ + 1)
+          def #{method}(node)
+            return if already_migrated_file?
+
+            super if method(__method__).super_method
+          end
+        RUBY
+      end
+      # rubocop:enable Style/DocumentDynamicEvalDefinition
+
+      private
+
+      def already_migrated_file?
+        return false unless migrated_schema_version
+
+        match_data = File.basename(processed_source.file_path).match(/(?<timestamp>\d{14})/)
+        schema_version = match_data['timestamp'] if match_data
+
+        return false unless schema_version
+
+        schema_version <= migrated_schema_version.to_s # Ignore applied migration files.
+      end
+
+      def migrated_schema_version
+        config.for_all_cops.fetch('MigratedSchemaVersion', nil)
+      end
     end
   end
 end

lib/rubocop/cop/rails/add_column_index.rb

@@ -19,6 +19,7 @@ module Rails
       class AddColumnIndex < Base
         extend AutoCorrector
         include RangeHelp
+        prepend MigrationsHelper
 
         MSG = '`add_column` does not accept an `index` key, use `add_index` instead.'
         RESTRICT_ON_SEND = %i[add_column].freeze

lib/rubocop/cop/rails/bulk_change_table.rb

@@ -65,6 +65,7 @@ module Rails
       #   end
       class BulkChangeTable < Base
         include DatabaseTypeResolvable
+        prepend MigrationsHelper
 
         MSG_FOR_CHANGE_TABLE = <<~MSG.chomp
           You can combine alter queries using `bulk: true` options.

lib/rubocop/cop/rails/dangerous_column_names.rb

@@ -14,6 +14,8 @@ module Rails
       #   # good
       #   add_column :users, :saved
       class DangerousColumnNames < Base # rubocop:disable Metrics/ClassLength
+        prepend MigrationsHelper
+
         COLUMN_TYPE_METHOD_NAMES = %i[
           bigint
           binary

lib/rubocop/cop/rails/migration_class_name.rb

@@ -20,7 +20,7 @@ module Rails
       #
       class MigrationClassName < Base
         extend AutoCorrector
-        include MigrationsHelper
+        prepend MigrationsHelper
 
         MSG = 'Replace with `%<camelized_basename>s` that matches the file name.'
 

lib/rubocop/cop/rails/not_null_column.rb

@@ -41,6 +41,7 @@ module Rails
       #   change_column_null :products, :category_id, false
       class NotNullColumn < Base
         include DatabaseTypeResolvable
+        prepend MigrationsHelper
 
         MSG = 'Do not add a NOT NULL column without a default value.'
         RESTRICT_ON_SEND = %i[add_column add_reference].freeze