Add cop to ensure reversibility of add_concurrent_index

db/migrate/20160615142710_add_index_on_requested_at_to_members.rb

@@ -3,7 +3,11 @@ class AddIndexOnRequestedAtToMembers < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :members, :requested_at
   end
+
+  def down
+    remove_index :members, :requested_at if index_exists? :members, :requested_at
+  end
 end

db/migrate/20160620115026_add_index_on_runners_locked.rb

@@ -6,7 +6,11 @@ class AddIndexOnRunnersLocked < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :ci_runners, :locked
   end
+
+  def down
+    remove_index :ci_runners, :locked if index_exists? :ci_runners, :locked
+  end
 end

db/migrate/20160715134306_add_index_for_pipeline_user_id.rb

@@ -3,7 +3,11 @@ class AddIndexForPipelineUserId < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :ci_commits, :user_id
   end
+
+  def down
+    remove_index :ci_commits, :user_id if index_exists? :ci_commits, :user_id
+  end
 end

db/migrate/20160805041956_add_deleted_at_to_namespaces.rb

@@ -5,8 +5,15 @@ class AddDeletedAtToNamespaces < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_column :namespaces, :deleted_at, :datetime
+
     add_concurrent_index :namespaces, :deleted_at
   end
+
+  def down
+    remove_index :namespaces, :deleted_at if index_exists? :namespaces, :deleted_at
+
+    remove_column :namespaces, :deleted_at
+  end
 end

db/migrate/20160808085602_add_index_for_build_token.rb

@@ -6,7 +6,11 @@ class AddIndexForBuildToken < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :ci_builds, :token, unique: true
   end
+
+  def down
+    remove_index :ci_builds, :token, unique: true if index_exists? :ci_builds, :token, unique: true
+  end
 end

db/migrate/20160819221631_add_index_to_note_discussion_id.rb

@@ -8,7 +8,11 @@ class AddIndexToNoteDiscussionId < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :notes, :discussion_id
   end
+
+  def down
+    remove_index :notes, :discussion_id if index_exists? :notes, :discussion_id
+  end
 end

db/migrate/20160819232256_add_incoming_email_token_to_users.rb

@@ -9,8 +9,15 @@ class AddIncomingEmailTokenToUsers < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_column :users, :incoming_email_token, :string
+
     add_concurrent_index :users, :incoming_email_token
   end
+
+  def down
+    remove_index :users, :incoming_email_token if index_exists? :users, :incoming_email_token
+
+    remove_column :users, :incoming_email_token
+  end
 end

db/migrate/20160919145149_add_group_id_to_labels.rb

@@ -5,9 +5,15 @@ class AddGroupIdToLabels < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_column :labels, :group_id, :integer
     add_foreign_key :labels, :namespaces, column: :group_id, on_delete: :cascade # rubocop: disable Migration/AddConcurrentForeignKey
     add_concurrent_index :labels, :group_id
   end
+
+  def down
+    remove_index :labels, :group_id if index_exists? :labels, :group_id
+    remove_foreign_key :labels, :namespaces, column: :group_id
+    remove_column :labels, :group_id
+  end
 end

db/migrate/20160920160832_add_index_to_labels_title.rb

@@ -5,7 +5,11 @@ class AddIndexToLabelsTitle < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :labels, :title
   end
+
+  def down
+    remove_index :labels, :title if index_exists? :labels, :title
+  end
 end

db/migrate/20161020083353_add_pipeline_id_to_merge_request_metrics.rb

@@ -25,9 +25,15 @@ class AddPipelineIdToMergeRequestMetrics < ActiveRecord::Migration
   # comments:
   # disable_ddl_transaction!
 
-  def change
+  def up
     add_column :merge_request_metrics, :pipeline_id, :integer
-    add_concurrent_index :merge_request_metrics, :pipeline_id
     add_foreign_key :merge_request_metrics, :ci_commits, column: :pipeline_id, on_delete: :cascade # rubocop: disable Migration/AddConcurrentForeignKey
+    add_concurrent_index :merge_request_metrics, :pipeline_id
+  end
+
+  def down
+    remove_index :merge_request_metrics, :pipeline_id if index_exists? :merge_request_metrics, :pipeline_id
+    remove_foreign_key :merge_request_metrics, :ci_commits, column: :pipeline_id
+    remove_column :merge_request_metrics, :pipeline_id
   end
 end

db/migrate/20161106185620_add_project_import_data_project_index.rb

@@ -6,7 +6,11 @@ class AddProjectImportDataProjectIndex < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :project_import_data, :project_id
   end
+
+  def down
+    remove_index :project_import_data, :project_id if index_exists? :project_import_data, :project_id
+  end
 end

db/migrate/20161124111395_add_index_to_parent_id.rb

@@ -8,7 +8,11 @@ class AddIndexToParentId < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index(:namespaces, [:parent_id, :id], unique: true)
   end
+
+  def down
+    remove_index :namespaces, [:parent_id, :id] if index_exists? :namespaces, [:parent_id, :id]
+  end
 end

db/migrate/20161202152035_add_index_to_routes.rb

@@ -9,8 +9,13 @@ class AddIndexToRoutes < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index(:routes, :path, unique: true)
     add_concurrent_index(:routes, [:source_type, :source_id], unique: true)
   end
+
+  def down
+    remove_index(:routes, :path) if index_exists? :routes, :path
+    remove_index(:routes, [:source_type, :source_id]) if index_exists? :routes, [:source_type, :source_id]
+  end
 end

db/migrate/20161209153400_add_unique_index_for_environment_slug.rb

@@ -9,7 +9,11 @@ class AddUniqueIndexForEnvironmentSlug < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :environments, [:project_id, :slug], unique: true
   end
+
+  def down
+    remove_index :environments, [:project_id, :slug], unique: true if index_exists? :environments, [:project_id, :slug]
+  end
 end

db/migrate/20170204181513_add_index_to_labels_for_type_and_project.rb

@@ -5,7 +5,11 @@ class AddIndexToLabelsForTypeAndProject < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :labels, [:type, :project_id]
   end
+
+  def down
+    remove_index :labels, [:type, :project_id] if index_exists? :labels, [:type, :project_id]
+  end
 end

db/migrate/20170210062829_add_index_to_labels_for_title_and_project.rb

@@ -5,8 +5,13 @@ class AddIndexToLabelsForTitleAndProject < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :labels, :title
     add_concurrent_index :labels, :project_id
   end
+
+  def down
+    remove_index :labels, :title if index_exists? :labels, :title
+    remove_index :labels, :project_id if index_exists? :labels, :project_id
+  end
 end

db/migrate/20170210075922_add_index_to_ci_trigger_requests_for_commit_id.rb

@@ -5,7 +5,11 @@ class AddIndexToCiTriggerRequestsForCommitId < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
+  def up
     add_concurrent_index :ci_trigger_requests, :commit_id
   end
+
+  def down
+    remove_index :ci_trigger_requests, :commit_id if index_exists? :ci_trigger_requests, :commit_id
+  end
 end

db/migrate/20170210103609_add_index_to_user_agent_detail.rb

@@ -8,7 +8,11 @@ class AddIndexToUserAgentDetail < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
-    add_concurrent_index(:user_agent_details, [:subject_id, :subject_type])
+  def up
+    add_concurrent_index :user_agent_details, [:subject_id, :subject_type]
+  end
+
+  def down
+    remove_index :user_agent_details, [:subject_id, :subject_type] if index_exists? :user_agent_details, [:subject_id, :subject_type]
   end
 end

db/migrate/20170216135621_add_index_for_latest_successful_pipeline.rb

@@ -4,7 +4,11 @@ class AddIndexForLatestSuccessfulPipeline < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def change
-    add_concurrent_index(:ci_commits, [:gl_project_id, :ref, :status])
+  def up
+    add_concurrent_index :ci_commits, [:gl_project_id, :ref, :status]
+  end
+
+  def down
+    remove_index :ci_commits, [:gl_project_id, :ref, :status] if index_exists? :ci_commits, [:gl_project_id, :ref, :status]
   end
 end

rubocop/cop/migration/add_concurrent_index.rb

+require_relative '../../migration_helpers'
+
+module RuboCop
+  module Cop
+    module Migration
+      # Cop that checks if `add_concurrent_index` is used with `up`/`down` methods
+      # and not `change`.
+      class AddConcurrentIndex < RuboCop::Cop::Cop
+        include MigrationHelpers
+
+        MSG = '`add_concurrent_index` is not reversible so you must manually define ' \
+          'the `up` and `down` methods in your migration class, using `remove_index` in `down`'.freeze
+
+        def on_send(node)
+          return unless in_migration?(node)
+
+          name = node.children[1]
+
+          return unless name == :add_concurrent_index
+
+          node.each_ancestor(:def) do |def_node|
+            next unless method_name(def_node) == :change
+
+            add_offense(def_node, :name)
+          end
+        end
+
+        def method_name(node)
+          node.children.first
+        end
+      end
+    end
+  end
+end

rubocop/rubocop.rb

@@ -3,4 +3,5 @@ require_relative 'cop/gem_fetcher'
 require_relative 'cop/migration/add_column'
 require_relative 'cop/migration/add_column_with_default'
 require_relative 'cop/migration/add_concurrent_foreign_key'
+require_relative 'cop/migration/add_concurrent_index'
 require_relative 'cop/migration/add_index'

spec/rubocop/cop/migration/add_concurrent_index_spec.rb

+require 'spec_helper'
+
+require 'rubocop'
+require 'rubocop/rspec/support'
+
+require_relative '../../../../rubocop/cop/migration/add_concurrent_index'
+
+describe RuboCop::Cop::Migration::AddConcurrentIndex do
+  include CopHelper
+
+  subject(:cop) { described_class.new }
+
+  context 'in migration' do
+    before do
+      allow(cop).to receive(:in_migration?).and_return(true)
+    end
+
+    it 'registers an offense when add_concurrent_index is used inside a change method' do
+      inspect_source(cop, 'def change; add_concurrent_index :table, :column; end')
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(1)
+        expect(cop.offenses.map(&:line)).to eq([1])
+      end
+    end
+
+    it 'registers no offense when add_concurrent_index is used inside an up method' do
+      inspect_source(cop, 'def up; add_concurrent_index :table, :column; end')
+
+      expect(cop.offenses.size).to eq(0)
+    end
+  end
+
+  context 'outside of migration' do
+    it 'registers no offense' do
+      inspect_source(cop, 'def change; add_concurrent_index :table, :column; end')
+
+      expect(cop.offenses.size).to eq(0)
+    end
+  end
+end