test_migrations.py 文件源码

def test_add_check_constraint(self):
        project_state = self.set_up_test_model()
        operation = migrations.AlterField(
            model_name='pony',
            name='pink',
            field=models.PositiveIntegerField(default=3)
        )
        new_state = project_state.clone()
        operation.state_forwards('tests', new_state)

        self.assertNoConstraint('tests_pony', ['pink'], 'check')

        with connection.schema_editor() as editor:
            operation.database_forwards('tests', editor, project_state, new_state)

        self.assertConstraint('tests_pony', ['pink'], 'check')

        with connection.schema_editor() as editor:
            operation.database_backwards('tests', editor, new_state, project_state)

        self.assertNoConstraint('tests_pony', ['pink'], 'check')