def test_valid_timestamp_true(self, mock_time):
cache = Cache(5, 60.0)
cache._items = {"k1": ["v1", 20.0]}
mock_time.return_value = 50.0
self.assertTrue(cache._valid_timestamp("k1"))
mock_time.assert_called_once()
mock_time.reset_mock()
mock_time.return_value = 80.0
self.assertTrue(cache._valid_timestamp("k1"))
mock_time.assert_called_once()
def test_valid_timestamp_false(self, mock_time):
cache = Cache(5, 60.0)
cache._items = {"k1": ["v1", 20.0]}
mock_time.return_value = 100.0
self.assertFalse(cache._valid_timestamp("k1"))
mock_time.assert_called_once()