test_sys.py 文件源码

def test_original_displayhook(self):
        import builtins
        out = io.StringIO()
        sys.stdout = out

        dh = sys.__displayhook__

        self.assertRaises(TypeError, dh)
        if hasattr(builtins, "_"):
            del builtins._

        dh(None)
        self.assertEqual(out.getvalue(), "")
        self.assertTrue(not hasattr(builtins, "_"))
        dh(42)
        self.assertEqual(out.getvalue(), "42\n")
        self.assertEqual(builtins._, 42)

        del sys.stdout
        self.assertRaises(RuntimeError, dh, 42)