assertThrows(Exception.class, () -> {
            future.get(5, TimeUnit.SECONDS);
        });

        client.close();
    }

    @Test
    void testNotificationDelivery() throws Exception {
        // Setup successful registration
        WitnessRegisterResponse mockResponse = mock(WitnessRegisterResponse.class);
        lenient().when(mockResponse.isSuccess()).thenReturn(true);