Added cop Migration/ChangeTableReferences (#47)

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 # main
 
+* Added cop `Migration/ChangeTableReferences` ([#47](https://github.com/petalmd/rubocop-petal/pull/47))
 * Added cop `Migration/AlwaysBulkChangeTable` ([#46](https://github.com/petalmd/rubocop-petal/pull/46))
 
 # v1.0.0 (2023-05-15)

README.md

@@ -54,7 +54,7 @@ bundle exec rake 'new_cop[Rails/MyNewCop]'
 ```
 
 Have a look to [RuboCop documentation](https://docs.rubocop.org/rubocop/1.23/development.html) to get started with
-_node pattern_.
+_node pattern_. [Rubocop AST](https://github.com/rubocop/rubocop-ast/blob/master/docs/modules/ROOT/pages/node_pattern.adoc)
 
 ## Release
 

config/default.yml

@@ -11,6 +11,12 @@ Migration/AlwaysBulkChangeTable:
   Include:
     - db/migrate/**
 
+Migration/ChangeTableReferences:
+  Description: 'Prevent using `t.references` or `t.belongs_to` in a change_table.'
+  Enabled: true
+  Include:
+    - db/migrate/**
+
 Migration/ForeignKeyOption:
   Description: 'Specify the foreign key option to create the constraint.'
   Enabled: true

lib/rubocop/cop/migration/change_table_references.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Migration
+      # Prevent using `t.references` or `t.belongs_to` in a change_table.
+      # Internally, `t.references` use multiple `ALTER TABLE` statements.
+      # Since Rails cannot transform automatically `t.references` inside
+      # a `change_table bulk: true` we can manually create the equivalent
+      # `ALTER TABLE` statement using `t.bigint`, `t.index` and `t.foreign_key`.
+      #
+      #   #bad
+      #   change_table :subscriptions, bulk: true do |t|
+      #     t.references :user, null: false, foreign_key: true
+      #   end
+      #
+      #   #good
+      #   change_table :subscriptions, bulk: true do |t|
+      #     t.bigint :user_id, null: false
+      #     t.index :user_id
+      #     t.foreign_key :users, column: :user_id
+      #   end
+      class ChangeTableReferences < Base
+        MSG = 'Use a combination of `t.bigint`, `t.index` and `t.foreign_key` in a change_table.'
+
+        # @!method add_references_in_block?(node)
+        def_node_search :add_references_in_block?, <<~PATTERN
+          (send lvar /references|belongs_to/ ...)
+        PATTERN
+
+        # @!method change_table?(node)
+        def_node_search :change_table?, <<~PATTERN
+          (send nil? :change_table ...)
+        PATTERN
+
+        def on_block(node)
+          return unless change_table?(node)
+
+          references_node = node.children.detect { |n| add_references_in_block?(n) }
+          return unless references_node
+
+          arguments = references_node.child_nodes[1]
+          references_methods_range = references_node.source_range.with(end_pos: arguments.source_range.begin_pos - 1)
+          add_offense(references_methods_range)
+        end
+      end
+    end
+  end
+end

spec/rubocop/cop/migration/change_table_references_spec.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Migration::ChangeTableReferences, :config do
+  it 'registers an offense when using references in a change_table' do
+    expect_offense(<<~RUBY)
+      change_table :subscriptions, bulk: true do |t|
+         t.references :user, null: false, foreign_key: true
+         ^^^^^^^^^^^^ Use a combination of `t.bigint`, `t.index` and `t.foreign_key` in a change_table.
+      end
+    RUBY
+
+    expect_offense(<<~RUBY)
+      change_table :subscriptions, bulk: true do |t|
+         t.belongs_to :user, null: false, foreign_key: true
+         ^^^^^^^^^^^^ Use a combination of `t.bigint`, `t.index` and `t.foreign_key` in a change_table.
+      end
+    RUBY
+  end
+
+  it 'does not register an offense when using references in a create_table' do
+    expect_no_offenses(<<~RUBY)
+      create_table :subscriptions do |t|
+         t.belongs_to :user, null: false, foreign_key: true
+      end
+    RUBY
+  end
+
+  it 'does not register an offense when not using references in a create_table' do
+    expect_no_offenses(<<~RUBY)
+      change_table :subscriptions do |t|
+         t.index :user_id
+      end
+    RUBY
+  end
+end