testing instance based migrations

activerecord/lib/active_record/migration.rb

@@ -306,11 +306,13 @@ module ActiveRecord
 
     def up
       self.class.delegate = self
+      return unless self.class.respond_to?(:up)
       self.class.up
     end
 
     def down
       self.class.delegate = self
+      return unless self.class.respond_to?(:down)
       self.class.down
     end
 

activerecord/test/cases/migration_test.rb

@@ -1166,6 +1166,44 @@ if ActiveRecord::Base.connection.supports_migrations?
       assert_raise(ActiveRecord::StatementInvalid) { Reminder.find(:first) }
     end
 
+    class MockMigration < ActiveRecord::Migration
+      attr_reader :went_up, :went_down
+      def initialize
+        @went_up   = false
+        @went_down = false
+      end
+
+      def up
+        @went_up = true
+        super
+      end
+
+      def down
+        @went_down = true
+        super
+      end
+    end
+
+    def test_instance_based_migration_up
+      migration = MockMigration.new
+      assert !migration.went_up, 'have not gone up'
+      assert !migration.went_down, 'have not gone down'
+
+      migration.migrate :up
+      assert migration.went_up, 'have gone up'
+      assert !migration.went_down, 'have not gone down'
+    end
+
+    def test_instance_based_migration_down
+      migration = MockMigration.new
+      assert !migration.went_up, 'have not gone up'
+      assert !migration.went_down, 'have not gone down'
+
+      migration.migrate :down
+      assert !migration.went_up, 'have gone up'
+      assert migration.went_down, 'have not gone down'
+    end
+
     def test_migrator_one_up
       assert !Person.column_methods_hash.include?(:last_name)
       assert !Reminder.table_exists?