def test_invalid_disconnect(self):
        """
        Test disconnecting an unconnected receiver.

        @raise AssertionError: If the test fails.
        """
        mediator = Mediator()
        try:
            mediator.disconnect('foo', self.dog.set_sound)
            mediator.disconnect('bar', self.cat.set_sound)
        except:
            raise AssertionError()

        Test disconnecting an unconnected receiver.

        @raise AssertionError: If the test fails.
        
tests/behavioral_tests/test_mediator.py