'`database` checks are only run when their tag is specified.'

def test_database_checks_not_run_by_default(self):

    def f1(**kwargs):
        return [5]
    registry = CheckRegistry()
    registry.register(Tags.database)(f1)
    errors = registry.run_checks()
    self.assertEqual(errors, [])
    errors2 = registry.run_checks(tags=[Tags.database])
    self.assertEqual(errors2, [5])
