def test_wrappedModule(self):
        """
        Deprecating an attribute in a module replaces and wraps that module
        instance, in C{sys.modules}, with a
        L{twisted.python.deprecate._ModuleProxy} instance but only if it hasn't
        already been wrapped.
        """
        sys.modules[self._testModuleName] = mod = types.ModuleType('foo')
        self.addCleanup(sys.modules.pop, self._testModuleName)

        setattr(mod, 'first', 1)
        setattr(mod, 'second', 2)

        deprecate.deprecatedModuleAttribute(
            Version('Twisted', 8, 0, 0),
            'message',
            self._testModuleName,
            'first')

        proxy = sys.modules[self._testModuleName]
        self.assertNotEqual(proxy, mod)

        deprecate.deprecatedModuleAttribute(
            Version('Twisted', 8, 0, 0),
            'message',
            self._testModuleName,
            'second')

        self.assertIs(proxy, sys.modules[self._testModuleName])

        Deprecating an attribute in a module replaces and wraps that module
        instance, in C{sys.modules}, with a
        L{twisted.python.deprecate._ModuleProxy} instance but only if it hasn't
        already been wrapped.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_deprecate.py