1 files changed, 118 insertions, 0 deletions
diff --git a/activerecord/test/cases/migration/compatibility_test.rb b/activerecord/test/cases/migration/compatibility_test.rb
new file mode 100644
index 0000000000..60ca90464d
--- /dev/null
+++ b/activerecord/test/cases/migration/compatibility_test.rb
@@ -0,0 +1,118 @@
+require 'cases/helper'
+
+module ActiveRecord
+  class Migration
+    class CompatibilityTest < ActiveRecord::TestCase
+      attr_reader :connection
+      self.use_transactional_tests = false
+
+      def setup
+        super
+        @connection = ActiveRecord::Base.connection
+        @verbose_was = ActiveRecord::Migration.verbose
+        ActiveRecord::Migration.verbose = false
+
+        connection.create_table :testings do |t|
+          t.column :foo, :string, :limit => 100
+          t.column :bar, :string, :limit => 100
+        end
+      end
+
+      teardown do
+        connection.drop_table :testings rescue nil
+        ActiveRecord::Migration.verbose = @verbose_was
+        ActiveRecord::SchemaMigration.delete_all rescue nil
+      end
+
+      def test_migration_doesnt_remove_named_index
+        connection.add_index :testings, :foo, :name => "custom_index_name"
+
+        migration = Class.new(ActiveRecord::Migration[4.2]) {
+          def version; 101 end
+          def migrate(x)
+            remove_index :testings, :foo
+          end
+        }.new
+
+        assert connection.index_exists?(:testings, :foo, name: "custom_index_name")
+        assert_raise(StandardError) { ActiveRecord::Migrator.new(:up, [migration]).migrate }
+        assert connection.index_exists?(:testings, :foo, name: "custom_index_name")
+      end
+
+      def test_migration_does_remove_unnamed_index
+        connection.add_index :testings, :bar
+
+        migration = Class.new(ActiveRecord::Migration[4.2]) {
+          def version; 101 end
+          def migrate(x)
+            remove_index :testings, :bar
+          end
+        }.new
+
+        assert connection.index_exists?(:testings, :bar)
+        ActiveRecord::Migrator.new(:up, [migration]).migrate
+        assert_not connection.index_exists?(:testings, :bar)
+      end
+
+      def test_references_does_not_add_index_by_default
+        migration = Class.new(ActiveRecord::Migration) {
+          def migrate(x)
+            create_table :more_testings do |t|
+              t.references :foo
+              t.belongs_to :bar, index: false
+            end
+          end
+        }.new
+
+        ActiveRecord::Migrator.new(:up, [migration]).migrate
+
+        assert_not connection.index_exists?(:more_testings, :foo_id)
+        assert_not connection.index_exists?(:more_testings, :bar_id)
+      ensure
+        connection.drop_table :more_testings rescue nil
+      end
+
+      def test_timestamps_have_null_constraints_if_not_present_in_migration_of_create_table
+        migration = Class.new(ActiveRecord::Migration) {
+          def migrate(x)
+            create_table :more_testings do |t|
+              t.timestamps
+            end
+          end
+        }.new
+
+        ActiveRecord::Migrator.new(:up, [migration]).migrate
+
+        assert connection.columns(:more_testings).find { |c| c.name == 'created_at' }.null
+        assert connection.columns(:more_testings).find { |c| c.name == 'updated_at' }.null
+      ensure
+        connection.drop_table :more_testings rescue nil
+      end
+
+      def test_timestamps_have_null_constraints_if_not_present_in_migration_for_adding_timestamps_to_existing_table
+        migration = Class.new(ActiveRecord::Migration) {
+          def migrate(x)
+            add_timestamps :testings
+          end
+        }.new
+
+        ActiveRecord::Migrator.new(:up, [migration]).migrate
+
+        assert connection.columns(:testings).find { |c| c.name == 'created_at' }.null
+        assert connection.columns(:testings).find { |c| c.name == 'updated_at' }.null
+      end
+
+      def test_legacy_migrations_get_deprecation_warning_when_run
+        migration = Class.new(ActiveRecord::Migration) {
+          def up
+            add_column :testings, :baz, :string
+          end
+        }
+
+        assert_deprecated do
+          migration.migrate :up
+        end
+      end
+    end
+  end
+end