public class RemoteServiceCommand extends HystrixCommand<String> {
    private RemoteService remoteService;

    RemoteServiceCommand(Setter config, RemoteService remoteService) {
        super(config);
        this.remoteService = remoteService;
    }

    @Override
    protected String run() throws Exception {
        return remoteService.execute();
    }
}


public class RemoteService {
    static final String SUCCESS = "Success";

    private long wait;

    RemoteService(long wait) {
        this.wait = wait;
    }

    String execute() throws InterruptedException {
        TimeUnit.MILLISECONDS.sleep(wait);
        return SUCCESS;
    }
}

public class RemoteServiceTest {
    private static final Logger LOGGER = LoggerFactory.getLogger(RemoteServiceTestCommand.class);

    private static final HystrixCommandGroupKey GROUP_KEY = Factory.asKey("RemoteServiceGroup");

    private HystrixCommand.Setter baseConfig;

    @BeforeEach
    void setUp() {
        baseConfig = HystrixCommand.Setter.withGroupKey(GROUP_KEY);
    }

    @Test
    void testWithTimeoutOf100AndDefaultSettings() {
        var remoteService = new RemoteService(100L);

        assertEquals(SUCCESS, new RemoteServiceCommand(baseConfig, remoteService).execute());
    }

    @Test
    void testWithCircuitBreakerSetup() throws InterruptedException {
        var circuitBreakerProperties = HystrixCommandProperties.Setter()
            .withExecutionTimeoutInMilliseconds(1_000)
            .withCircuitBreakerSleepWindowInMilliseconds(2_000)
            .withExecutionIsolationStrategy(ExecutionIsolationStrategy.THREAD)
            .withCircuitBreakerEnabled(true)
            .withCircuitBreakerRequestVolumeThreshold(1);

        var threadPoolProperties = HystrixThreadPoolProperties.Setter()
            .withMaxQueueSize(1)
            .withCoreSize(1)
            .withQueueSizeRejectionThreshold(1);

        var config = baseConfig
            .andCommandPropertiesDefaults(circuitBreakerProperties)
            .andThreadPoolPropertiesDefaults(threadPoolProperties);

        assertNull(callRemoteService(config, 1_000L));
        assertNull(callRemoteService(config, 1_000L));
        assertNull(callRemoteService(config, 500L));

        TimeUnit.SECONDS.sleep(2L);

        assertEquals(SUCCESS, callRemoteService(config, 500L));
    }

    private String callRemoteService(HystrixCommand.Setter config, long timeout) {
        try {
            return new RemoteServiceCommand(config, new RemoteService(timeout)).execute();
        } catch (HystrixRuntimeException e) {
            var cause = e.getCause();
            if (cause.getMessage() != null) {
                LOGGER.info("{} {}", e.getMessage(), cause.getMessage());
            } else {
                LOGGER.info(e.getMessage());
            }

            return null;
        }
    }
}