def testCanImplementPostValidate(self): getter = DartSdkPathSetting(name='doesnt_matter') getter.get = mock.Mock() getter.validate_sdk_path = mock.Mock() getter.post_validate = mock.Mock() getter.get.return_value = 'chorizo' getter.validate_sdk_path = lambda x: x getter.post_validate.return_value = 'morcilla' class dummy: my_setting = getter d = dummy() self.assertEqual('morcilla', d.my_setting)