def test_decorateTestSuiteReferences(self):
        """
        When decorating a test suite in-place, the number of references to the
        test objects in that test suite should stay the same.

        Previously, L{unittest.decorate} recreated a test suite, so the
        original suite kept references to the test objects. This test is here
        to ensure the problem doesn't reappear again.
        """
        getrefcount = getattr(sys, 'getrefcount', None)
        if getrefcount is None:
            raise unittest.SkipTest(
                "getrefcount not supported on this platform")
        test = self.TestCase()
        suite = unittest.TestSuite([test])
        count1 = getrefcount(test)
        unittest.decorate(suite, unittest.TestDecorator)
        count2 = getrefcount(test)
        self.assertEqual(count1, count2)

        When decorating a test suite in-place, the number of references to the
        test objects in that test suite should stay the same.

        Previously, L{unittest.decorate} recreated a test suite, so the
        original suite kept references to the test objects. This test is here
        to ensure the problem doesn't reappear again.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/test/test_tests.py