def METHOD_NAME(self):
    output = mock.create_autospec(output_lib.Output)
    w = writer_lib.Writer(output)
    with mock.patch.object(time, "time") as mock_time:
        mock_time.return_value = 12345.678
        w.add_scalar("foo", 42.0, 12)
    output.emit_scalar.assert_called_once()
    _, kwargs = output.emit_scalar.call_args
    self.assertEqual(12345.678, kwargs["wall_time"])