io.github.resilience4j.retry.Retry Java Examples

/**
 * This method returns a desired Tax(taxAmount, taxPercentage) value when the TaxService is up. 
 * If the TaxService is down, it applies a combination of following fault tolerance patterns 
 * in a sequence: TimeLimiter, CircuitBreaker and Retry using a Callable. When all the attempts 
 * are exhausted it calls a fallback method to recover from failure and offers the default tax value.
 * 
 * @param amount
 * @return
 */
public Tax applyResiliencePatterns(BigDecimal amount) {

	CircuitBreaker circuitBreaker = configureCircuitBreaker();
	TimeLimiter timeLimiter = configureTimeLimiter();
	Retry retry = configureRetry();
	
	Supplier<CompletableFuture<Tax>> futureSupplier = () -> CompletableFuture.supplyAsync(() -> salesOrderService.supplyTax(amount));
	Callable<Tax> callable = TimeLimiter.decorateFutureSupplier(timeLimiter, futureSupplier);
	callable = CircuitBreaker.decorateCallable(circuitBreaker, callable);
	callable = Retry.decorateCallable(retry, callable);
	
	//Executing the decorated callable and recovering from any exception by calling the fallback method
	Try<Tax> result = Try.ofCallable(callable).recover(throwable -> taxServiceFallback(amount));
	return result.get();
}
 

@Test
public void testDecorateRunnable() {
    CircuitBreaker circuitBreaker = CircuitBreaker.ofDefaults("helloBackend");
    Runnable decoratedRunnable = Decorators
        .ofRunnable(() -> helloWorldService.sayHelloWorld())
        .withCircuitBreaker(circuitBreaker)
        .withRetry(Retry.ofDefaults("id"))
        .withRateLimiter(RateLimiter.ofDefaults("testName"))
        .withBulkhead(Bulkhead.ofDefaults("testName"))
        .decorate();

    decoratedRunnable.run();

    CircuitBreaker.Metrics metrics = circuitBreaker.getMetrics();
    assertThat(metrics.getNumberOfBufferedCalls()).isEqualTo(1);
    assertThat(metrics.getNumberOfSuccessfulCalls()).isEqualTo(1);
    then(helloWorldService).should(times(1)).sayHelloWorld();
}
 

@Test
public void doNotRetryFromPredicateUsingCompletable() {
    RetryConfig config = RetryConfig.custom()
        .retryOnException(t -> t instanceof IOException)
        .waitDuration(Duration.ofMillis(50))
        .maxAttempts(3).build();
    Retry retry = Retry.of("testName", config);
    doThrow(new HelloWorldException()).when(helloWorldService).sayHelloWorld();

    Completable.fromRunnable(helloWorldService::sayHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .assertError(HelloWorldException.class)
        .assertNotComplete()
        .assertSubscribed();

    then(helloWorldService).should().sayHelloWorld();
    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(1);
    assertThat(metrics.getNumberOfFailedCallsWithRetryAttempt()).isEqualTo(0);
}
 

@Test
public void testDecorateCompletionStage() throws ExecutionException, InterruptedException {
    given(helloWorldService.returnHelloWorld()).willReturn("Hello world");
    CircuitBreaker circuitBreaker = CircuitBreaker.ofDefaults("helloBackend");
    Supplier<CompletionStage<String>> completionStageSupplier =
        () -> CompletableFuture.supplyAsync(helloWorldService::returnHelloWorld);
    CompletionStage<String> completionStage = Decorators
        .ofCompletionStage(completionStageSupplier)
        .withCircuitBreaker(circuitBreaker)
        .withRetry(Retry.ofDefaults("id"), Executors.newSingleThreadScheduledExecutor())
        .withBulkhead(Bulkhead.ofDefaults("testName"))
        .get();

    String value = completionStage.toCompletableFuture().get();

    assertThat(value).isEqualTo("Hello world");
    CircuitBreaker.Metrics metrics = circuitBreaker.getMetrics();
    assertThat(metrics.getNumberOfBufferedCalls()).isEqualTo(1);
    assertThat(metrics.getNumberOfSuccessfulCalls()).isEqualTo(1);
    then(helloWorldService).should(times(1)).returnHelloWorld();
}
 

@Test
public void returnOnErrorUsingCompletable() throws InterruptedException {
    RetryConfig config = retryConfig();
    Retry retry = Retry.of("testName", config);
    RetryTransformer<Object> retryTransformer = RetryTransformer.of(retry);
    doThrow(new HelloWorldException()).when(helloWorldService).sayHelloWorld();

    Completable.fromRunnable(helloWorldService::sayHelloWorld)
        .compose(retryTransformer)
        .test()
        .await()
        .assertError(HelloWorldException.class)
        .assertNotComplete();
    Completable.fromRunnable(helloWorldService::sayHelloWorld)
        .compose(retryTransformer)
        .test()
        .await()
        .assertError(HelloWorldException.class)
        .assertNotComplete();

    then(helloWorldService).should(times(6)).sayHelloWorld();
    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithRetryAttempt()).isEqualTo(2);
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(0);
}
 

@Test
public void shouldNotRetryWhenItThrowErrorSingle() {
    RetryConfig config = retryConfig();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willThrow(new Error("BAM!"));

    Single.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .assertError(Error.class)
        .assertNotComplete()
        .assertSubscribed();

    then(helloWorldService).should().returnHelloWorld();
    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithRetryAttempt()).isEqualTo(0);
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(0);
}
 

@Test
public void testDecorateSupplier() {
    given(helloWorldService.returnHelloWorld()).willReturn("Hello world");
    CircuitBreaker circuitBreaker = CircuitBreaker.ofDefaults("helloBackend");
    Supplier<String> decoratedSupplier = Decorators
        .ofSupplier(() -> helloWorldService.returnHelloWorld())
        .withCircuitBreaker(circuitBreaker)
        .withRetry(Retry.ofDefaults("id"))
        .withRateLimiter(RateLimiter.ofDefaults("testName"))
        .withBulkhead(Bulkhead.ofDefaults("testName"))
        .decorate();

    String result = decoratedSupplier.get();

    assertThat(result).isEqualTo("Hello world");
    CircuitBreaker.Metrics metrics = circuitBreaker.getMetrics();
    assertThat(metrics.getNumberOfBufferedCalls()).isEqualTo(1);
    assertThat(metrics.getNumberOfSuccessfulCalls()).isEqualTo(1);
    then(helloWorldService).should(times(1)).returnHelloWorld();
}
 

@Test
public void doNotRetryFromPredicateUsingFlowable() {
    RetryConfig config = RetryConfig.custom()
        .retryOnException(t -> t instanceof IOException)
        .waitDuration(Duration.ofMillis(50))
        .maxAttempts(3).build();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willThrow(new HelloWorldException());

    Flowable.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .assertError(HelloWorldException.class)
        .assertNotComplete();

    then(helloWorldService).should().returnHelloWorld();
    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(1);
    assertThat(metrics.getNumberOfFailedCallsWithRetryAttempt()).isEqualTo(0);
}
 

@Test
public void shouldAddMetricsForANewlyCreatedRetry() {
    Retry newRetry = retryRegistry.retry("backendB");

    assertThat(taggedRetryMetricsPublisher.meterIdMap).containsKeys("backendA", "backendB");
    assertThat(taggedRetryMetricsPublisher.meterIdMap.get("backendA")).hasSize(4);
    assertThat(taggedRetryMetricsPublisher.meterIdMap.get("backendB")).hasSize(4);

    List<Meter> meters = meterRegistry.getMeters();
    assertThat(meters).hasSize(8);

    Collection<FunctionCounter> counters = meterRegistry.get(DEFAULT_RETRY_CALLS)
        .functionCounters();

    Optional<FunctionCounter> successfulWithoutRetry = MetricsTestHelper
        .findMeterByKindAndNameTags(counters, "successful_without_retry", newRetry.getName());
    assertThat(successfulWithoutRetry).isPresent();
    assertThat(successfulWithoutRetry.get().count())
        .isEqualTo(newRetry.getMetrics().getNumberOfSuccessfulCallsWithoutRetryAttempt());
}
 

@Test
public void returnOnErrorUsingObservable() throws InterruptedException {
    RetryConfig config = retryConfig();
    Retry retry = Retry.of("testName", config);
    RetryTransformer<Object> retryTransformer = RetryTransformer.of(retry);
    given(helloWorldService.returnHelloWorld())
        .willThrow(new HelloWorldException());

    Observable.fromCallable(helloWorldService::returnHelloWorld)
        .compose(retryTransformer)
        .test()
        .await()
        .assertError(HelloWorldException.class)
        .assertNotComplete();
    Observable.fromCallable(helloWorldService::returnHelloWorld)
        .compose(retryTransformer)
        .test()
        .await()
        .assertError(HelloWorldException.class)
        .assertNotComplete();

    then(helloWorldService).should(times(6)).returnHelloWorld();
    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithRetryAttempt()).isEqualTo(2);
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(0);
}
 

@Test
public void returnOnErrorUsingMaybe() throws InterruptedException {
    RetryConfig config = retryConfig();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willThrow(new HelloWorldException());
    Maybe.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .await()
        .assertError(HelloWorldException.class)
        .assertNotComplete();
    Maybe.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .await()
        .assertError(HelloWorldException.class)
        .assertNotComplete();

    then(helloWorldService).should(times(6)).returnHelloWorld();

    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithRetryAttempt()).isEqualTo(2);
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(0);
}
 

@Test
public void shouldReplaceMetrics() {
    Collection<FunctionCounter> counters = meterRegistry.get(DEFAULT_RETRY_CALLS).functionCounters();
    Optional<FunctionCounter> successfulWithoutRetry = MetricsTestHelper.findMeterByKindAndNameTags(counters,
        "successful_without_retry", retry.getName());
    assertThat(successfulWithoutRetry).isPresent();
    assertThat(successfulWithoutRetry.get().count())
        .isEqualTo(retry.getMetrics().getNumberOfSuccessfulCallsWithoutRetryAttempt());

    Retry newRetry = Retry.of(retry.getName(), RetryConfig.custom().maxAttempts(1).build());

    retryRegistry.replace(retry.getName(), newRetry);

    counters = meterRegistry.get(DEFAULT_RETRY_CALLS).functionCounters();
    successfulWithoutRetry = MetricsTestHelper
        .findMeterByKindAndNameTags(counters, "successful_without_retry",
        newRetry.getName());
    assertThat(successfulWithoutRetry).isPresent();
    assertThat(successfulWithoutRetry.get().count())
        .isEqualTo(newRetry.getMetrics().getNumberOfSuccessfulCallsWithoutRetryAttempt());
}
 

private <T> Supplier<T> decorateSupplierWithOnSuccess(Retry retry, Supplier<T> supplier) {
    return () -> {
        Retry.Context<T> context = retry.context();
        do {
            try {
                T result = supplier.get();
                final boolean validationOfResult = context.onResult(result);
                if (!validationOfResult) {
                    context.onSuccess();
                    return result;
                }
            } catch (RuntimeException runtimeException) {
                context.onRuntimeError(runtimeException);
            }
        } while (true);
    };
}
 

@Test
public void retryOnResultUsingMono() {
    RetryConfig config = RetryConfig.<String>custom()
        .retryOnResult("retry"::equals)
        .waitDuration(Duration.ofMillis(10))
        .maxAttempts(3).build();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willReturn("retry")
        .willReturn("success");

    StepVerifier.create(Mono.fromCallable(helloWorldService::returnHelloWorld)
        .transformDeferred(RetryOperator.of(retry)))
        .expectSubscription()
        .expectNext("success")
        .expectComplete()
        .verify(Duration.ofSeconds(1));

    then(helloWorldService).should(times(2)).returnHelloWorld();
    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(0);
    assertThat(metrics.getNumberOfSuccessfulCallsWithRetryAttempt()).isEqualTo(1);
}
 

@Test
public void retryOnResultUsingMaybe() throws InterruptedException {
    RetryConfig config = RetryConfig.<String>custom()
        .retryOnResult("retry"::equals)
        .waitDuration(Duration.ofMillis(50))
        .maxAttempts(3).build();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willReturn("retry")
        .willReturn("success");
    Maybe.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .await()
        .assertValueCount(1)
        .assertValue("success")
        .assertComplete();

    then(helloWorldService).should(times(2)).returnHelloWorld();

    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(0);
    assertThat(metrics.getNumberOfSuccessfulCallsWithRetryAttempt()).isEqualTo(1);
}
 

@Test
public void retryOnResultFailAfterMaxAttemptsUsingMaybe() throws InterruptedException {
    RetryConfig config = RetryConfig.<String>custom()
        .retryOnResult("retry"::equals)
        .waitDuration(Duration.ofMillis(50))
        .maxAttempts(3).build();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willReturn("retry");

    Maybe.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .await()
        .assertValueCount(1)
        .assertValue("retry")
        .assertComplete()
        .assertSubscribed();

    then(helloWorldService).should(times(3)).returnHelloWorld();
}
 

@Test
public void shouldReplaceMetrics() {
    Collection<FunctionCounter> counters = meterRegistry.get(DEFAULT_RETRY_CALLS)
        .functionCounters();
    Optional<FunctionCounter> successfulWithoutRetry = findMeterByKindAndNameTags(counters,
        "successful_without_retry", retry.getName());
    assertThat(successfulWithoutRetry).isPresent();
    assertThat(successfulWithoutRetry.get().count())
        .isEqualTo(retry.getMetrics().getNumberOfSuccessfulCallsWithoutRetryAttempt());

    Retry newRetry = Retry.of(retry.getName(), RetryConfig.custom().maxAttempts(1).build());

    retryRegistry.replace(retry.getName(), newRetry);

    counters = meterRegistry.get(DEFAULT_RETRY_CALLS).functionCounters();
    successfulWithoutRetry = findMeterByKindAndNameTags(counters, "successful_without_retry",
        newRetry.getName());
    assertThat(successfulWithoutRetry).isPresent();
    assertThat(successfulWithoutRetry.get().count())
        .isEqualTo(newRetry.getMetrics().getNumberOfSuccessfulCallsWithoutRetryAttempt());
}
 

@Test
public void retryOnResultFailAfterMaxAttemptsUsingObservable() throws InterruptedException {
    RetryConfig config = RetryConfig.<String>custom()
        .retryOnResult("retry"::equals)
        .waitDuration(Duration.ofMillis(50))
        .maxAttempts(3).build();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willReturn("retry");

    Observable.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .await()
        .assertValueCount(1)
        .assertValue("retry")
        .assertComplete();

    then(helloWorldService).should(times(3)).returnHelloWorld();
}
 

@Test
public void doNotRetryFromPredicateUsingMaybe() {
    RetryConfig config = RetryConfig.custom()
        .retryOnException(t -> t instanceof IOException)
        .waitDuration(Duration.ofMillis(50))
        .maxAttempts(3).build();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willThrow(new HelloWorldException());

    Maybe.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .assertError(HelloWorldException.class)
        .assertNotComplete();

    then(helloWorldService).should().returnHelloWorld();

    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(1);
    assertThat(metrics.getNumberOfFailedCallsWithRetryAttempt()).isEqualTo(0);
}
 

@Test
public void shouldUseCustomPrefix() throws Throwable {
    Retry retry = givenMetricRegistry("testPrefix", metricRegistry);
    given(helloWorldService.returnHelloWorld()).willReturn("Hello world");

    String value = retry.executeSupplier(helloWorldService::returnHelloWorld);

    assertThat(value).isEqualTo("Hello world");
    then(helloWorldService).should(times(1)).returnHelloWorld();
    assertThat(metricRegistry.getMetrics()).hasSize(4);
    assertThat(
        metricRegistry.getGauges().get("testPrefix.testName." + SUCCESSFUL_CALLS_WITH_RETRY)
            .getValue()).isEqualTo(0L);
    assertThat(
        metricRegistry.getGauges().get("testPrefix.testName." + SUCCESSFUL_CALLS_WITHOUT_RETRY)
            .getValue()).isEqualTo(1L);
    assertThat(metricRegistry.getGauges().get("testPrefix.testName." + FAILED_CALLS_WITH_RETRY)
        .getValue()).isEqualTo(0L);
    assertThat(
        metricRegistry.getGauges().get("testPrefix.testName." + FAILED_CALLS_WITHOUT_RETRY)
            .getValue()).isEqualTo(0L);
}
 

@Test
public void whenRetryIsUsed_thenItWorksAsExpected() {
    RetryConfig config = RetryConfig.custom().maxAttempts(2).build();
    RetryRegistry registry = RetryRegistry.of(config);
    Retry retry = registry.retry("my");
    Function<Integer, Void> decorated = Retry.decorateFunction(retry, (Integer s) -> {
        service.process(s);
        return null;
    });

    when(service.process(anyInt())).thenThrow(new RuntimeException());
    try {
        decorated.apply(1);
        fail("Expected an exception to be thrown if all retries failed");
    } catch (Exception e) {
        verify(service, times(2)).process(any(Integer.class));
    }
}
 

@Test
public void doNotRetryFromPredicateUsingSingle() {
    RetryConfig config = RetryConfig.custom()
        .retryOnException(t -> t instanceof IOException)
        .waitDuration(Duration.ofMillis(50))
        .maxAttempts(3).build();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willThrow(new HelloWorldException());
    Single.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .assertError(HelloWorldException.class)
        .assertNotComplete()
        .assertSubscribed();

    then(helloWorldService).should().returnHelloWorld();
    Retry.Metrics metrics = retry.getMetrics();

    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(1);
    assertThat(metrics.getNumberOfFailedCallsWithRetryAttempt()).isEqualTo(0);
}
 

@Test
public void testDecorateCheckedSupplier() throws IOException {
    given(helloWorldService.returnHelloWorldWithException()).willReturn("Hello world");
    CircuitBreaker circuitBreaker = CircuitBreaker.ofDefaults("helloBackend");
    CheckedFunction0<String> decoratedSupplier = Decorators
        .ofCheckedSupplier(() -> helloWorldService.returnHelloWorldWithException())
        .withCircuitBreaker(circuitBreaker)
        .withRetry(Retry.ofDefaults("id"))
        .withRateLimiter(RateLimiter.ofDefaults("testName"))
        .withBulkhead(Bulkhead.ofDefaults("testName"))
        .decorate();

    String result = Try.of(decoratedSupplier).get();

    assertThat(result).isEqualTo("Hello world");
    CircuitBreaker.Metrics metrics = circuitBreaker.getMetrics();
    assertThat(metrics.getNumberOfBufferedCalls()).isEqualTo(1);
    assertThat(metrics.getNumberOfSuccessfulCalls()).isEqualTo(1);
    then(helloWorldService).should(times(1)).returnHelloWorldWithException();
}
 

@Override
public List<MetricFamilySamples> collect() {
    GaugeMetricFamily retryCallsFamily = new GaugeMetricFamily(
        names.getCallsMetricName(),
        "The number of calls",
        LabelNames.NAME_AND_KIND
    );

    for (Retry retry : retryRegistry.getAllRetries()) {
        retryCallsFamily.addMetric(asList(retry.getName(), "successful_without_retry"),
            retry.getMetrics().getNumberOfSuccessfulCallsWithoutRetryAttempt());
        retryCallsFamily.addMetric(asList(retry.getName(), "successful_with_retry"),
            retry.getMetrics().getNumberOfSuccessfulCallsWithRetryAttempt());
        retryCallsFamily.addMetric(asList(retry.getName(), "failed_without_retry"),
            retry.getMetrics().getNumberOfFailedCallsWithoutRetryAttempt());
        retryCallsFamily.addMetric(asList(retry.getName(), "failed_with_retry"),
            retry.getMetrics().getNumberOfFailedCallsWithRetryAttempt());

    }

    return Collections.singletonList(retryCallsFamily);
}
 

private void shouldCompleteFutureAfterAttemptsInCaseOfExceptionAtSyncStage(int noOfAttempts) {
    given(helloWorldService.returnHelloWorld())
        .willThrow(new HelloWorldException());
    Retry retryContext = Retry.of(
        "id",
        RetryConfig
            .custom()
            .maxAttempts(noOfAttempts)
            .build());
    Supplier<CompletionStage<String>> supplier = Retry.decorateCompletionStage(
        retryContext,
        scheduler,
        () -> helloWorldService.returnHelloWorld());

    Try<String> resultTry = Try.of(() -> awaitResult(supplier.get()));

    then(helloWorldService).should(times(noOfAttempts)).returnHelloWorld();
    assertThat(resultTry.isFailure()).isTrue();
    assertThat(resultTry.getCause().getCause()).isInstanceOf(HelloWorldException.class);
}
 

private void shouldCompleteFutureAfterAttemptsInCaseOfExceptionAtAsyncStage(int noOfAttempts) {
    CompletableFuture<String> failedFuture = new CompletableFuture<>();
    failedFuture.completeExceptionally(new HelloWorldException());
    given(helloWorldService.returnHelloWorld())
        .willReturn(failedFuture);
    Retry retryContext = Retry.of(
        "id",
        RetryConfig
            .custom()
            .maxAttempts(noOfAttempts)
            .build());
    Supplier<CompletionStage<String>> supplier = Retry.decorateCompletionStage(
        retryContext,
        scheduler,
        () -> helloWorldService.returnHelloWorld());

    Try<String> resultTry = Try.of(() -> awaitResult(supplier.get()));

    then(helloWorldService).should(times(noOfAttempts)).returnHelloWorld();
    assertThat(resultTry.isFailure()).isTrue();
    assertThat(resultTry.getCause().getCause()).isInstanceOf(HelloWorldException.class);
}
 

private void shouldCompleteFutureAfterAttemptsInCaseOfRetyOnResultAtAsyncStage(int noOfAttempts,
    String retryResponse) {
    given(helloWorldService.returnHelloWorld())
        .willReturn(completedFuture("Hello world"));
    Retry retryContext = Retry.of(
        "id",
        RetryConfig
            .<String>custom()
            .maxAttempts(noOfAttempts)
            .retryOnResult(s -> s.contains(retryResponse))
            .build());
    Supplier<CompletionStage<String>> supplier = Retry.decorateCompletionStage(
        retryContext,
        scheduler,
        () -> helloWorldService.returnHelloWorld());

    Try<String> resultTry = Try.of(() -> awaitResult(supplier.get()));

    then(helloWorldService).should(times(noOfAttempts)).returnHelloWorld();
    assertThat(resultTry.isSuccess()).isTrue();
}
 

@Test
public void shouldReturnAfterTwoAttempts() {
    willThrow(new HelloWorldException()).willDoNothing().given(helloWorldService)
        .sayHelloWorld();
    Retry retry = Retry.ofDefaults("id");
    TestSubscriber<RetryEvent.Type> testSubscriber = toFlowable(retry.getEventPublisher())
        .map(RetryEvent::getEventType)
        .test();
    CheckedRunnable retryableRunnable = Retry
        .decorateCheckedRunnable(retry, helloWorldService::sayHelloWorld);

    Try<Void> result = Try.run(retryableRunnable);

    then(helloWorldService).should(times(2)).sayHelloWorld();
    assertThat(result.isSuccess()).isTrue();
    assertThat(sleptTime).isEqualTo(RetryConfig.DEFAULT_WAIT_DURATION);
    testSubscriber.assertValueCount(2)
        .assertValues(RetryEvent.Type.RETRY, RetryEvent.Type.SUCCESS);
}
 

@Before
public void setup() {
    registry = new CollectorRegistry();
    retryRegistry = RetryRegistry.ofDefaults();
    retry = retryRegistry.retry("backendA");

    RetryMetricsCollector.ofRetryRegistry(retryRegistry).register(registry);

    retry.executeSupplier(() -> "return");

    Supplier<String> supplier = Retry.decorateSupplier(retry, () -> {
        throw new RuntimeException();
    });

    Try.ofSupplier(supplier);
}
 

@Test
public void shouldNotRetryWhenItThrowErrorSingle() {
    RetryConfig config = retryConfig();
    Retry retry = Retry.of("testName", config);
    given(helloWorldService.returnHelloWorld())
        .willThrow(new Error("BAM!"));

    Single.fromCallable(helloWorldService::returnHelloWorld)
        .compose(RetryTransformer.of(retry))
        .test()
        .assertError(Error.class)
        .assertNotComplete();

    then(helloWorldService).should().returnHelloWorld();
    Retry.Metrics metrics = retry.getMetrics();
    assertThat(metrics.getNumberOfFailedCallsWithRetryAttempt()).isEqualTo(0);
    assertThat(metrics.getNumberOfFailedCallsWithoutRetryAttempt()).isEqualTo(0);
}