def test_loadModuleWith_testSuite(self):
        """
        Check that C{testSuite} is used when present and other L{TestCase}s are
        not included.
        """
        from twisted.trial.test import mockcustomsuite2
        suite = self.loader.loadModule(mockcustomsuite2)
        self.assertEqual(0, suite.countTestCases())
        self.assertEqual("MyCustomSuite", getattr(suite, 'name', None))

        Check that C{testSuite} is used when present and other L{TestCase}s are
        not included.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/test/test_loader.py