Add test coverage for bulk altering timestamps

activerecord/test/cases/migration_test.rb

@@ -1177,6 +1177,42 @@ if ActiveRecord::Base.connection.supports_bulk_alter?
       assert column(:qualification_experience)
     end
 
+    def test_adding_timestamps
+      with_bulk_change_table do |t|
+        t.string :title
+      end
+
+      assert column(:title)
+
+      assert_queries(1) do
+        with_bulk_change_table do |t|
+          t.timestamps
+          t.remove :title
+        end
+      end
+
+      [:created_at, :updated_at].each { |c| assert column(c) }
+      assert_not column(:title)
+    end
+
+    def test_removing_timestamps
+      with_bulk_change_table do |t|
+        t.timestamps
+      end
+
+      [:created_at, :updated_at].each { |c| assert column(c) }
+
+      assert_queries(1) do
+        with_bulk_change_table do |t|
+          t.remove_timestamps
+          t.string :title
+        end
+      end
+
+      [:created_at, :updated_at].each { |c| assert_not column(c) }
+      assert column(:title)
+    end
+
     def test_adding_indexes
       with_bulk_change_table do |t|
         t.string :username