From 50de40daa27f61c0e5ba52d6c2d11f6e93a6c8a6 Mon Sep 17 00:00:00 2001 From: SGWebFreelancer Date: Tue, 28 Nov 2023 10:19:27 +0800 Subject: [PATCH 1/2] Unit Testing for CompletableFuture class --- .../CompletableFutureTest.java | 150 ++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureTest.java diff --git a/core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureTest.java b/core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureTest.java new file mode 100644 index 0000000000..25e8ea4c81 --- /dev/null +++ b/core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureTest.java @@ -0,0 +1,150 @@ +package com.baeldung.concurrent.completablefuture; + +import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertFalse; +import static org.junit.jupiter.api.Assertions.assertThrows; +import static org.junit.jupiter.api.Assertions.assertTrue; +import static org.mockito.ArgumentMatchers.any; +import static org.mockito.Mockito.mock; +import static org.mockito.Mockito.when; + +import java.util.Arrays; +import java.util.List; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.CompletionException; +import java.util.concurrent.ExecutionException; +import java.util.concurrent.Executor; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.TimeoutException; +import java.util.stream.Collectors; + +import org.junit.Test; + +public class CompletableFutureTest { + + @Test + public void givenAsyncTask_whenProcessingAsyncSucceed_thenReturnSuccess() throws ExecutionException, InterruptedException { + Microservice mockMicroserviceA = mock(Microservice.class); + Microservice mockMicroserviceB = mock(Microservice.class); + + when(mockMicroserviceA.retrieveAsync(any())).thenReturn(CompletableFuture.completedFuture("Hello")); + when(mockMicroserviceB.retrieveAsync(any())).thenReturn(CompletableFuture.completedFuture("World")); + + CompletableFuture resultFuture = processAsync(List.of(mockMicroserviceA, mockMicroserviceB)); + + String result = resultFuture.get(); + assertEquals("HelloWorld", result); + } + + @Test + public void givenAsyncTask_whenProcessingAsyncWithException_thenReturnException() throws ExecutionException, InterruptedException { + Microservice mockMicroserviceA = mock(Microservice.class); + Microservice mockMicroserviceB = mock(Microservice.class); + + when(mockMicroserviceA.retrieveAsync(any())).thenReturn(CompletableFuture.completedFuture("Hello")); + when(mockMicroserviceB.retrieveAsync(any())).thenReturn(CompletableFuture.failedFuture(new RuntimeException("Simulated Exception"))); + CompletableFuture resultFuture = processAsync(List.of(mockMicroserviceA, mockMicroserviceB)); + // Use assertThrows to verify that the expected exception is thrown + ExecutionException exception = assertThrows(ExecutionException.class, resultFuture::get); + // Assert the exception message + assertEquals("Simulated Exception", exception.getCause() + .getMessage()); + } + + @Test + public void givenAsyncTask_whenProcessingAsyncWithTimeout_thenHandleTimeoutException() throws ExecutionException, InterruptedException { + Microservice mockMicroserviceA = mock(Microservice.class); + Microservice mockMicroserviceB = mock(Microservice.class); + Executor delayedExecutor = CompletableFuture.delayedExecutor(200, TimeUnit.MILLISECONDS); + when(mockMicroserviceA.retrieveAsync(any())).thenReturn(CompletableFuture.supplyAsync(() -> "Hello", delayedExecutor)); + Executor delayedExecutor2 = CompletableFuture.delayedExecutor(500, TimeUnit.MILLISECONDS); + when(mockMicroserviceB.retrieveAsync(any())).thenReturn(CompletableFuture.supplyAsync(() -> "World", delayedExecutor2)); + CompletableFuture resultFuture = processAsync(List.of(mockMicroserviceA, mockMicroserviceB)); + assertThrows(TimeoutException.class, () -> resultFuture.get(300, TimeUnit.MILLISECONDS)); + } + + @Test + public void givenCompletableFuture_whenCompleted_thenStateIsDone() { + Executor delayedExecutor = CompletableFuture.delayedExecutor(200, TimeUnit.MILLISECONDS); + CompletableFuture cf1 = CompletableFuture.supplyAsync(() -> "Hello", delayedExecutor); + CompletableFuture cf2 = CompletableFuture.supplyAsync(() -> " World"); + CompletableFuture cf3 = CompletableFuture.supplyAsync(() -> "!"); + CompletableFuture[] cfs = new CompletableFuture[] { cf1, cf2, cf3 }; + + CompletableFuture allCf = CompletableFuture.allOf(cfs); + + assertFalse(allCf.isDone()); + allCf.join(); + String result = Arrays.stream(cfs) + .map(CompletableFuture::join) + .collect(Collectors.joining()); + + assertFalse(allCf.isCancelled()); + assertTrue(allCf.isDone()); + assertFalse(allCf.isCompletedExceptionally()); + assertEquals(result, "Hello World!"); + } + + @Test + public void givenCompletableFuture_whenCompletedWithException_thenStateIsCompletedExceptionally() throws ExecutionException, InterruptedException { + Executor delayedExecutor = CompletableFuture.delayedExecutor(200, TimeUnit.MILLISECONDS); + CompletableFuture cf1 = CompletableFuture.supplyAsync(() -> "Hello", delayedExecutor); + CompletableFuture cf2 = CompletableFuture.failedFuture(new RuntimeException("Simulated Exception")); + CompletableFuture cf3 = CompletableFuture.supplyAsync(() -> "!"); + CompletableFuture[] cfs = new CompletableFuture[] { cf1, cf2, cf3 }; + + CompletableFuture allCf = CompletableFuture.allOf(cfs); + + assertFalse(allCf.isDone()); + assertFalse(allCf.isCompletedExceptionally()); + + // Exception is expected, assert the cause + CompletionException exception = assertThrows(CompletionException.class, allCf::join); + + assertEquals("Simulated Exception", exception.getCause() + .getMessage()); + assertTrue(allCf.isCompletedExceptionally()); + assertTrue(allCf.isDone()); + assertFalse(allCf.isCancelled()); + } + + @Test + public void givenCompletableFuture_whenCancelled_thenStateIsCancelled() throws ExecutionException, InterruptedException { + Executor delayedExecutor = CompletableFuture.delayedExecutor(200, TimeUnit.MILLISECONDS); + CompletableFuture cf1 = CompletableFuture.supplyAsync(() -> "Hello", delayedExecutor); + CompletableFuture cf2 = CompletableFuture.supplyAsync(() -> " World"); + CompletableFuture cf3 = CompletableFuture.supplyAsync(() -> "!"); + CompletableFuture[] cfs = new CompletableFuture[] { cf1, cf2, cf3 }; + CompletableFuture allCf = CompletableFuture.allOf(cfs); + assertFalse(allCf.isDone()); + assertFalse(allCf.isCompletedExceptionally()); + allCf.cancel(true); + assertTrue(allCf.isCancelled()); + assertTrue(allCf.isDone()); + } + + CompletableFuture processAsync(List microservices) { + List> dataFetchFutures = fetchDataAsync(microservices); + return combineResults(dataFetchFutures); + } + + private List> fetchDataAsync(List microservices) { + return microservices.stream() + .map(client -> client.retrieveAsync("")) + .collect(Collectors.toList()); + } + + private CompletableFuture combineResults(List> dataFetchFutures) { + return CompletableFuture.allOf(dataFetchFutures.toArray(new CompletableFuture[0])) + .thenApply(v -> dataFetchFutures.stream() + .map(future -> future.exceptionally(ex -> { + throw new CompletionException(ex); + }) + .join()) + .collect(Collectors.joining())); + } + + interface Microservice { + CompletableFuture retrieveAsync(String input); + } +} From 93b63daa27efd5c20a69b5395f09a9c085b060cb Mon Sep 17 00:00:00 2001 From: SGWebFreelancer Date: Tue, 28 Nov 2023 10:24:39 +0800 Subject: [PATCH 2/2] Fix test file name --- ...ompletableFutureTest.java => CompletableFutureUnitTest.java} | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) rename core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/{CompletableFutureTest.java => CompletableFutureUnitTest.java} (99%) diff --git a/core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureTest.java b/core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureUnitTest.java similarity index 99% rename from core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureTest.java rename to core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureUnitTest.java index 25e8ea4c81..5953c6d87a 100644 --- a/core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureTest.java +++ b/core-java-modules/core-java-concurrency-2/src/test/java/com/baeldung/concurrent/completablefuture/CompletableFutureUnitTest.java @@ -20,7 +20,7 @@ import java.util.stream.Collectors; import org.junit.Test; -public class CompletableFutureTest { +public class CompletableFutureUnitTest { @Test public void givenAsyncTask_whenProcessingAsyncSucceed_thenReturnSuccess() throws ExecutionException, InterruptedException {