    def test_save_signal_state(self):
        """Tests that the signal state class works properly.

        The _SignalState class must set, save, and restore signals
        when needed.
        """
        if sys.platform == "win32":
            self.skipTest("Windows does not have signals.")

        def dummy_handler():
            """Assign dummy handler to an arbitrary signal."""
            pass
        self.assertNotEqual(signal.getsignal(signal.SIGWINCH), dummy_handler)
        signal_state = _SignalState()
        signal_state.set(signal.SIGWINCH, dummy_handler)
        self.assertEqual(signal.getsignal(signal.SIGWINCH), dummy_handler)
        signal_state.restore()
        self.assertNotEqual(signal.getsignal(signal.SIGWINCH), dummy_handler)
Tests that the signal state class works properly.

The _SignalState class must set, save, and restore signals
when needed.
tests/test_screen.py