为 Future 回调编写 junit 测试用例

Question

有人可以帮助为下面的代码部分（尤其是添加回调部分）编写 JUnit 测试吗？我不知道如何使用回调为 Listenablefuture 编写单元测试用例

    private void handleResponse(final ListenableFuture<UserRecordResult> response, CompletableFuture future) {

        Futures.addCallback(response, new FutureCallback<UserRecordResult>() {

            @Override
            public void onFailure(@Nonnull Throwable throwable) {

                future.completeExceptionally(new Exception("Fail to put record" + throwable.getMessage()));
            }

            @Override
            public void onSuccess(UserRecordResult result) {
                if(result.isSuccessful()) {
                    future.complete(true);
                } else {
                    future.completeExceptionally(new Exception("Fail to put record"));
                }
            }
        });
    }

Answer 1

您可以通过存根ListeneableFuture并按CompletableFuture以下方式进行测试：

@Test
public void completeExceptionallyOnCallbackFailure() {
    ListenableFuture<UserRecordResult> failureResponse = Futures.immediateFailedFuture(new RuntimeException());
    CompletableFuture future = new CompletableFuture();

    handleResponse(failureResponse, future);

    assertThat(future.isCompletedExceptionally(), equalTo(true));
}

@Test
public void completeExceptionallyIfUserRecordResultIsNotSuccessful() {
    UserRecordResult mockResult = Mockito.mock(UserRecordResult.class);
    Mockito.when(mockResult.isSuccessful()).thenReturn(false);

    ListenableFuture<UserRecordResult> failureResponse = Futures.immediateFuture(mockResult);
    CompletableFuture future = new CompletableFuture();

    handleResponse(failureResponse, future);

    assertThat(future.isCompletedExceptionally(), equalTo(true));
}

@Test
public void completeSuccessfully() throws ExecutionException, InterruptedException {
    UserRecordResult mockResult = Mockito.mock(UserRecordResult.class);
    Mockito.when(mockResult.isSuccessful()).thenReturn(true);

    ListenableFuture<UserRecordResult> successResponse = Futures.immediateFuture(mockResult);
    CompletableFuture future = new CompletableFuture();

    handleResponse(successResponse, future);

    assertThat(future.get(), equalTo(true));
}

此外，您可以使用以下方法断言实际的错误消息assertj：

@Test
public void verifyMessageIfCompletedExceptionallyAfterUserRecordResultIsNotSuccessful() {
    UserRecordResult mockResult = Mockito.mock(UserRecordResult.class);
    Mockito.when(mockResult.isSuccessful()).thenReturn(false);

    ListenableFuture<UserRecordResult> failureResponse = Futures.immediateFuture(mockResult);
    CompletableFuture future = new CompletableFuture();

    Assertions.assertThatThrownBy(() -> {
        handleResponse(failureResponse, future);
        future.get();
    })
    .isInstanceOf(Exception.class)
    .hasMessage("java.lang.Exception: Fail to put record");
}