Merge branch '32054-rails-should-use-timestamptz-database-type-for-postgresql' into 'master'

Add database helpers 'add_timestamps_with_timezone' and 'timestamps_with_timezone'

Closes #32054

See merge request !11229

changelogs/unreleased/32054-rails-should-use-timestamptz-database-type-for-postgresql.yml

+---
+title: Add database helpers 'add_timestamps_with_timezone' and 'timestamps_with_timezone'
+merge_request: 11229
+author: @blackst0ne

config/initializers/active_record_data_types.rb

+# ActiveRecord custom data type for storing datetimes with timezone information.
+# See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11229
+
+if Gitlab::Database.postgresql?
+  require 'active_record/connection_adapters/postgresql_adapter'
+
+  module ActiveRecord
+    module ConnectionAdapters
+      class PostgreSQLAdapter
+        NATIVE_DATABASE_TYPES.merge!(datetime_with_timezone: { name: 'timestamptz' })
+      end
+    end
+  end
+elsif Gitlab::Database.mysql?
+  require 'active_record/connection_adapters/mysql2_adapter'
+
+  module ActiveRecord
+    module ConnectionAdapters
+      class AbstractMysqlAdapter
+        NATIVE_DATABASE_TYPES.merge!(datetime_with_timezone: { name: 'timestamp' })
+      end
+    end
+  end
+end

config/initializers/active_record_table_definition.rb

+# ActiveRecord custom method definitions with timezone information.
+# See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11229
+
+require 'active_record/connection_adapters/abstract/schema_definitions'
+
+# Appends columns `created_at` and `updated_at` to a table.
+#
+# It is used in table creation like:
+# create_table 'users' do |t|
+#   t.timestamps_with_timezone
+# end
+module ActiveRecord
+  module ConnectionAdapters
+    class TableDefinition
+      def timestamps_with_timezone(**options)
+        options[:null] = false if options[:null].nil?
+
+        [:created_at, :updated_at].each do |column_name|
+          column(column_name, :datetime_with_timezone, options)
+        end
+      end
+    end
+  end
+end

db/migrate/20160314114439_add_requested_at_to_members.rb

+# rubocop:disable Migration/Datetime
 class AddRequestedAtToMembers < ActiveRecord::Migration
   def change
     add_column :members, :requested_at, :datetime

db/migrate/20160415062917_create_personal_access_tokens.rb

+# rubocop:disable Migration/Datetime
+# rubocop:disable Migration/Timestamps
 class CreatePersonalAccessTokens < ActiveRecord::Migration
   def change
     create_table :personal_access_tokens do |t|

db/migrate/20160610204157_add_deployments.rb

 # See http://doc.gitlab.com/ce/development/migration_style_guide.html
 # for more information on how to write migrations for GitLab.
 
+# rubocop:disable Migration/Datetime
 class AddDeployments < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20160610204158_add_environments.rb

 # See http://doc.gitlab.com/ce/development/migration_style_guide.html
 # for more information on how to write migrations for GitLab.
 
+# rubocop:disable Migration/Datetime
 class AddEnvironments < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20160705054938_add_protected_branches_push_access.rb

 # See http://doc.gitlab.com/ce/development/migration_style_guide.html
 # for more information on how to write migrations for GitLab.
 
+# rubocop:disable Migration/Timestamps
 class AddProtectedBranchesPushAccess < ActiveRecord::Migration
   DOWNTIME = false
 

db/migrate/20160705054952_add_protected_branches_merge_access.rb

 # See http://doc.gitlab.com/ce/development/migration_style_guide.html
 # for more information on how to write migrations for GitLab.
 
+# rubocop:disable Migration/Timestamps
 class AddProtectedBranchesMergeAccess < ActiveRecord::Migration
   DOWNTIME = false
 

db/migrate/20160724205507_add_resolved_to_notes.rb

+# rubocop:disable Migration/Datetime
 class AddResolvedToNotes < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20160727163552_create_user_agent_details.rb

+# rubocop:disable Migration/Timestamps
 class CreateUserAgentDetails < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20160727191041_create_boards.rb

+# rubocop:disable Migration/Timestamps
 class CreateBoards < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20160727193336_create_lists.rb

+# rubocop:disable Migration/Timestamps
 class CreateLists < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20160805041956_add_deleted_at_to_namespaces.rb

+# rubocop:disable Migration/Datetime
 # rubocop:disable RemoveIndex
 class AddDeletedAtToNamespaces < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers

db/migrate/20160824124900_add_table_issue_metrics.rb

 # See http://doc.gitlab.com/ce/development/migration_style_guide.html
 # for more information on how to write migrations for GitLab.
 
+# rubocop:disable Migration/Datetime
+# rubocop:disable Migration/Timestamps
 class AddTableIssueMetrics < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20160825052008_add_table_merge_request_metrics.rb

 # See http://doc.gitlab.com/ce/development/migration_style_guide.html
 # for more information on how to write migrations for GitLab.
 
+# rubocop:disable Migration/Datetime
+# rubocop:disable Migration/Timestamps
 class AddTableMergeRequestMetrics < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20160831214002_create_project_features.rb

+# rubocop:disable Migration/Timestamps
 class CreateProjectFeatures < ActiveRecord::Migration
   DOWNTIME = false
 

db/migrate/20160915042921_create_merge_requests_closing_issues.rb

 # See http://doc.gitlab.com/ce/development/migration_style_guide.html
 # for more information on how to write migrations for GitLab.
 
+# rubocop:disable Migration/Timestamps
 class CreateMergeRequestsClosingIssues < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20161014173530_create_label_priorities.rb

+# rubocop:disable Migration/Timestamps
 class CreateLabelPriorities < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20161113184239_create_user_chat_names_table.rb

+# rubocop:disable Migration/Datetime
+# rubocop:disable Migration/Timestamps
 class CreateUserChatNamesTable < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20161124111402_add_routes_table.rb

 # See http://doc.gitlab.com/ce/development/migration_style_guide.html
 # for more information on how to write migrations for GitLab.
 
+# rubocop:disable Migration/Timestamps
 class AddRoutesTable < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20161221152132_add_last_used_at_to_key.rb

+# rubocop:disable Migration/Datetime
 class AddLastUsedAtToKey < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20161223034646_create_timelogs_ce.rb

+# rubocop:disable Migration/Timestamps
 class CreateTimelogsCe < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20161228124936_change_expires_at_to_date_in_personal_access_tokens.rb

 # See http://doc.gitlab.com/ce/development/migration_style_guide.html
 # for more information on how to write migrations for GitLab.
 
+# rubocop:disable Migration/Datetime
 class ChangeExpiresAtToDateInPersonalAccessTokens < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170120131253_create_chat_teams.rb

+# rubocop:disable Migration/Timestamps
 class CreateChatTeams < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170130221926_create_uploads.rb

+# rubocop:disable Migration/Datetime
 class CreateUploads < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170222143317_drop_ci_projects.rb

+# rubocop:disable Migration/Datetime
 class DropCiProjects < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170301205639_remove_unused_ci_tables_and_columns.rb

+# rubocop:disable Migration/Datetime
 class RemoveUnusedCiTablesAndColumns < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170309173138_create_protected_tags.rb

+# rubocop:disable Migration/Timestamps
 class CreateProtectedTags < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170314082049_create_system_note_metadata.rb

+# rubocop:disable Migration/Timestamps
 class CreateSystemNoteMetadata < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170315194013_add_closed_at_to_issues.rb

+# rubocop:disable Migration/Datetime
 class AddClosedAtToIssues < ActiveRecord::Migration
   DOWNTIME = false
 

db/migrate/20170322013926_create_container_repository.rb

+# rubocop:disable Migration/Timestamps
 class CreateContainerRepository < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170329095907_create_ci_trigger_schedules.rb

+# rubocop:disable Migration/Datetime
 class CreateCiTriggerSchedules < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170425112128_create_pipeline_schedules_table.rb

+# rubocop:disable Migration/Datetime
+# rubocop:disable Migration/Timestamps
 class CreatePipelineSchedulesTable < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/migrate/20170427215854_create_redirect_routes.rb

+# rubocop:disable Migration/Timestamps
 class CreateRedirectRoutes < ActiveRecord::Migration
   # Set this constant to true if this migration requires downtime.
   DOWNTIME = false

db/migrate/20170503004125_add_last_repository_updated_at_to_projects.rb

+# rubocop:disable Migration/Datetime
 class AddLastRepositoryUpdatedAtToProjects < ActiveRecord::Migration
   DOWNTIME = false
 

db/migrate/20170523121229_create_conversational_development_index_metrics.rb

+# rubocop:disable Migration/Timestamps
 class CreateConversationalDevelopmentIndexMetrics < ActiveRecord::Migration
   DOWNTIME = false
 

db/migrate/20170525132202_create_pipeline_stages.rb

+# rubocop:disable Migration/Timestamps
 class CreatePipelineStages < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

db/post_migrate/20170425130047_drop_ci_trigger_schedules_table.rb

+# rubocop:disable Migration/Datetime
 class DropCiTriggerSchedulesTable < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 

doc/development/migration_style_guide.md

@@ -122,7 +122,7 @@ limit can vary from installation to installation. As a result it's recommended
 you do not use more than 32 threads in a single migration. Usually 4-8 threads
 should be more than enough.
 
-## Removing indices
+## Removing indexes
 
 When removing an index make sure to use the method `remove_concurrent_index` instead
 of the regular `remove_index` method. The `remove_concurrent_index` method
@@ -142,7 +142,7 @@ class MyMigration < ActiveRecord::Migration
 end
 ```
 
-## Adding indices
+## Adding indexes
 
 If you need to add a unique index please keep in mind there is the possibility
 of existing duplicates being present in the database. This means that should
@@ -222,6 +222,41 @@ add_column_with_default(:projects, :foo, :integer, default: 10, limit: 8)
 add_column(:projects, :foo, :integer, default: 10, limit: 8)
 ```
 
+## Timestamp column type
+
+By default, Rails uses the `timestamp` data type that stores timestamp data without timezone information.        
+The `timestamp` data type is used by calling either the `add_timestamps` or the `timestamps` method.       
+Also Rails converts the `:datetime` data type to the `timestamp` one.        
+
+Example:
+
+```ruby
+# timestamps
+create_table :users do |t|
+  t.timestamps
+end
+
+# add_timestamps
+def up
+  add_timestamps :users
+end
+
+# :datetime
+def up
+  add_column :users, :last_sign_in, :datetime
+end
+```
+
+Instead of using these methods one should use the following methods to store timestamps with timezones:
+
+* `add_timestamps_with_timezone`
+* `timestamps_with_timezone`
+
+This ensures all timestamps have a time zone specified. This in turn means existing timestamps won't
+suddenly use a different timezone when the system's timezone changes. It also makes it very clear which
+timezone was used in the first place.
+
+
 ## Testing
 
 Make sure that your migration works with MySQL and PostgreSQL with data. An

lib/gitlab/database/migration_helpers.rb

 module Gitlab
   module Database
     module MigrationHelpers
+      # Adds `created_at` and `updated_at` columns with timezone information.
+      #
+      # This method is an improved version of Rails' built-in method `add_timestamps`.
+      #
+      # Available options are:
+      # default - The default value for the column.
+      # null - When set to `true` the column will allow NULL values.
+      #        The default is to not allow NULL values.
+      def add_timestamps_with_timezone(table_name, options = {})
+        options[:null] = false if options[:null].nil?
+
+        [:created_at, :updated_at].each do |column_name|
+          if options[:default] && transaction_open?
+            raise '`add_timestamps_with_timezone` with default value cannot be run inside a transaction. ' \
+              'You can disable transactions by calling `disable_ddl_transaction!` ' \
+              'in the body of your migration class'
+          end
+
+          # If default value is presented, use `add_column_with_default` method instead.
+          if options[:default]
+            add_column_with_default(
+              table_name,
+              column_name,
+              :datetime_with_timezone,
+              default: options[:default],
+              allow_null: options[:null]
+            )
+          else
+            add_column(table_name, column_name, :datetime_with_timezone, options)
+          end
+        end
+      end
+
       # Creates a new index, concurrently when supported
       #
       # On PostgreSQL this method creates an index concurrently, on MySQL this

rubocop/cop/migration/add_timestamps.rb

+require_relative '../../migration_helpers'
+
+module RuboCop
+  module Cop
+    module Migration
+      # Cop that checks if 'add_timestamps' method is called with timezone information.
+      class AddTimestamps < RuboCop::Cop::Cop
+        include MigrationHelpers
+
+        MSG = 'Do not use `add_timestamps`, use `add_timestamps_with_timezone` instead'.freeze
+
+        # Check methods.
+        def on_send(node)
+          return unless in_migration?(node)
+
+          add_offense(node, :selector) if method_name(node) == :add_timestamps
+        end
+
+        def method_name(node)
+          node.children[1]
+        end
+      end
+    end
+  end
+end

rubocop/cop/migration/datetime.rb

+require_relative '../../migration_helpers'
+
+module RuboCop
+  module Cop
+    module Migration
+      # Cop that checks if datetime data type is added with timezone information.
+      class Datetime < RuboCop::Cop::Cop
+        include MigrationHelpers
+
+        MSG = 'Do not use the `datetime` data type, use `datetime_with_timezone` instead'.freeze
+
+        # Check methods in table creation.
+        def on_def(node)
+          return unless in_migration?(node)
+
+          node.each_descendant(:send) do |send_node|
+            add_offense(send_node, :selector) if method_name(send_node) == :datetime
+          end
+        end
+
+        # Check methods.
+        def on_send(node)
+          return unless in_migration?(node)
+
+          node.each_descendant do |descendant|
+            add_offense(node, :expression) if descendant.type == :sym && descendant.children.last == :datetime
+          end
+        end
+
+        def method_name(node)
+          node.children[1]
+        end
+      end
+    end
+  end
+end

rubocop/cop/migration/timestamps.rb

+require_relative '../../migration_helpers'
+
+module RuboCop
+  module Cop
+    module Migration
+      # Cop that checks if 'timestamps' method is called with timezone information.
+      class Timestamps < RuboCop::Cop::Cop
+        include MigrationHelpers
+
+        MSG = 'Do not use `timestamps`, use `timestamps_with_timezone` instead'.freeze
+
+        # Check methods in table creation.
+        def on_def(node)
+          return unless in_migration?(node)
+
+          node.each_descendant(:send) do |send_node|
+            add_offense(send_node, :selector) if method_name(send_node) == :timestamps
+          end
+        end
+
+        def method_name(node)
+          node.children[1]
+        end
+      end
+    end
+  end
+end

rubocop/rubocop.rb

@@ -8,7 +8,10 @@ require_relative 'cop/migration/add_column_with_default_to_large_table'
 require_relative 'cop/migration/add_concurrent_foreign_key'
 require_relative 'cop/migration/add_concurrent_index'
 require_relative 'cop/migration/add_index'
+require_relative 'cop/migration/add_timestamps'
+require_relative 'cop/migration/datetime'
 require_relative 'cop/migration/remove_concurrent_index'
 require_relative 'cop/migration/remove_index'
 require_relative 'cop/migration/reversible_add_column_with_default'
+require_relative 'cop/migration/timestamps'
 require_relative 'cop/migration/update_column_in_batches'

spec/lib/gitlab/database/migration_helpers_spec.rb

@@ -7,7 +7,42 @@ describe Gitlab::Database::MigrationHelpers, lib: true do
     )
   end
 
-  before { allow(model).to receive(:puts) }
+  before do
+    allow(model).to receive(:puts)
+  end
+
+  describe '#add_timestamps_with_timezone' do
+    before do
+      allow(model).to receive(:transaction_open?).and_return(false)
+    end
+
+    context 'using PostgreSQL' do
+      before do
+        allow(Gitlab::Database).to receive(:postgresql?).and_return(true)
+        allow(model).to receive(:disable_statement_timeout)
+      end
+
+      it 'adds "created_at" and "updated_at" fields with the "datetime_with_timezone" data type' do
+        expect(model).to receive(:add_column).with(:foo, :created_at, :datetime_with_timezone, { null: false })
+        expect(model).to receive(:add_column).with(:foo, :updated_at, :datetime_with_timezone, { null: false })
+
+        model.add_timestamps_with_timezone(:foo)
+      end
+    end
+
+    context 'using MySQL' do
+      before do
+        allow(Gitlab::Database).to receive(:postgresql?).and_return(false)
+      end
+
+      it 'adds "created_at" and "updated_at" fields with "datetime_with_timezone" data type' do
+        expect(model).to receive(:add_column).with(:foo, :created_at, :datetime_with_timezone, { null: false })
+        expect(model).to receive(:add_column).with(:foo, :updated_at, :datetime_with_timezone, { null: false })
+
+        model.add_timestamps_with_timezone(:foo)
+      end
+    end
+  end
 
   describe '#add_concurrent_index' do
     context 'outside a transaction' do

spec/rubocop/cop/migration/add_timestamps_spec.rb

+require 'spec_helper'
+
+require 'rubocop'
+require 'rubocop/rspec/support'
+
+require_relative '../../../../rubocop/cop/migration/add_timestamps'
+
+describe RuboCop::Cop::Migration::AddTimestamps do
+  include CopHelper
+
+  subject(:cop) { described_class.new }
+  let(:migration_with_add_timestamps) do
+    %q(
+      class Users < ActiveRecord::Migration
+        DOWNTIME = false
+
+        def change
+          add_column(:users, :username, :text)
+          add_timestamps(:users)
+        end
+      end
+    )
+  end
+
+  let(:migration_without_add_timestamps) do
+    %q(
+      class Users < ActiveRecord::Migration
+        DOWNTIME = false
+
+        def change
+          add_column(:users, :username, :text)
+        end
+      end
+    )
+  end
+
+  let(:migration_with_add_timestamps_with_timezone) do
+    %q(
+      class Users < ActiveRecord::Migration
+        DOWNTIME = false
+
+        def change
+          add_column(:users, :username, :text)
+          add_timestamps_with_timezone(:users)
+        end
+      end
+    )
+  end
+
+  context 'in migration' do
+    before do
+      allow(cop).to receive(:in_migration?).and_return(true)
+    end
+
+    it 'registers an offense when the "add_timestamps" method is used' do
+      inspect_source(cop, migration_with_add_timestamps)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(1)
+        expect(cop.offenses.map(&:line)).to eq([7])
+      end
+    end
+
+    it 'does not register an offense when the "add_timestamps" method is not used' do
+      inspect_source(cop, migration_without_add_timestamps)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(0)
+      end
+    end
+
+    it 'does not register an offense when the "add_timestamps_with_timezone" method is used' do
+      inspect_source(cop, migration_with_add_timestamps_with_timezone)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(0)
+      end
+    end
+  end
+
+  context 'outside of migration' do
+    it 'registers no offense' do
+      inspect_source(cop, migration_with_add_timestamps)
+      inspect_source(cop, migration_without_add_timestamps)
+      inspect_source(cop, migration_with_add_timestamps_with_timezone)
+
+      expect(cop.offenses.size).to eq(0)
+    end
+  end
+end

spec/rubocop/cop/migration/datetime_spec.rb

+require 'spec_helper'
+
+require 'rubocop'
+require 'rubocop/rspec/support'
+
+require_relative '../../../../rubocop/cop/migration/datetime'
+
+describe RuboCop::Cop::Migration::Datetime do
+  include CopHelper
+
+  subject(:cop) { described_class.new }
+  let(:migration_with_datetime) do
+    %q(
+      class Users < ActiveRecord::Migration
+        DOWNTIME = false
+
+        def change
+          add_column(:users, :username, :text)
+          add_column(:users, :last_sign_in, :datetime)
+        end
+      end
+    )
+  end
+
+  let(:migration_without_datetime) do
+    %q(
+      class Users < ActiveRecord::Migration
+        DOWNTIME = false
+
+        def change
+          add_column(:users, :username, :text)
+        end
+      end
+    )
+  end
+
+  let(:migration_with_datetime_with_timezone) do
+    %q(
+      class Users < ActiveRecord::Migration
+        DOWNTIME = false
+
+        def change
+          add_column(:users, :username, :text)
+          add_column(:users, :last_sign_in, :datetime_with_timezone)
+        end
+      end
+    )
+  end
+
+  context 'in migration' do
+    before do
+      allow(cop).to receive(:in_migration?).and_return(true)
+    end
+
+    it 'registers an offense when the ":datetime" data type is used' do
+      inspect_source(cop, migration_with_datetime)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(1)
+        expect(cop.offenses.map(&:line)).to eq([7])
+      end
+    end
+
+    it 'does not register an offense when the ":datetime" data type is not used' do
+      inspect_source(cop, migration_without_datetime)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(0)
+      end
+    end
+
+    it 'does not register an offense when the ":datetime_with_timezone" data type is used' do
+      inspect_source(cop, migration_with_datetime_with_timezone)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(0)
+      end
+    end
+  end
+
+  context 'outside of migration' do
+    it 'registers no offense' do
+      inspect_source(cop, migration_with_datetime)
+      inspect_source(cop, migration_without_datetime)
+      inspect_source(cop, migration_with_datetime_with_timezone)
+
+      expect(cop.offenses.size).to eq(0)
+    end
+  end
+end

spec/rubocop/cop/migration/timestamps_spec.rb

+require 'spec_helper'
+
+require 'rubocop'
+require 'rubocop/rspec/support'
+
+require_relative '../../../../rubocop/cop/migration/timestamps'
+
+describe RuboCop::Cop::Migration::Timestamps do
+  include CopHelper
+
+  subject(:cop) { described_class.new }
+  let(:migration_with_timestamps) do
+    %q(
+      class Users < ActiveRecord::Migration
+        DOWNTIME = false
+
+        def change
+          create_table :users do |t|
+            t.string :username, null: false
+            t.timestamps null: true
+            t.string :password
+          end
+        end
+      end
+    )
+  end
+
+  let(:migration_without_timestamps) do
+    %q(
+      class Users < ActiveRecord::Migration
+        DOWNTIME = false
+
+        def change
+          create_table :users do |t|
+            t.string :username, null: false
+            t.string :password
+          end
+        end
+      end
+    )
+  end
+
+  let(:migration_with_timestamps_with_timezone) do
+    %q(
+      class Users < ActiveRecord::Migration
+        DOWNTIME = false
+
+        def change
+          create_table :users do |t|
+            t.string :username, null: false
+            t.timestamps_with_timezone null: true
+            t.string :password
+          end
+        end
+      end
+    )
+  end
+
+  context 'in migration' do
+    before do
+      allow(cop).to receive(:in_migration?).and_return(true)
+    end
+
+    it 'registers an offense when the "timestamps" method is used' do
+      inspect_source(cop, migration_with_timestamps)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(1)
+        expect(cop.offenses.map(&:line)).to eq([8])
+      end
+    end
+
+    it 'does not register an offense when the "timestamps" method is not used' do
+      inspect_source(cop, migration_without_timestamps)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(0)
+      end
+    end
+
+    it 'does not register an offense when the "timestamps_with_timezone" method is used' do
+      inspect_source(cop, migration_with_timestamps_with_timezone)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(0)
+      end
+    end
+  end
+
+  context 'outside of migration' do
+    it 'registers no offense' do
+      inspect_source(cop, migration_with_timestamps)
+      inspect_source(cop, migration_without_timestamps)
+      inspect_source(cop, migration_with_timestamps_with_timezone)
+
+      expect(cop.offenses.size).to eq(0)
+    end
+  end
+end