单元测试网络响应.在调试时工作，而不是在实际运行时工作

问题描述

我目前正在尝试测试是否确实收到了网络响应.

I am currently attempting to test that a network response is actually being received.

虽然我知道这不是我在测试方面应该做的事情，但这是我自己的好奇心，如果可能的话，我想继续.

就目前而言，我已经成功创建了测试.请求被毫无问题地发送到排球队列.

As it stands, I have successfully created the test. A request is sent to a volley queue without issue.

现在奇怪的部分:

该请求永远不会执行.这是我如何测试它的想法:

That request is never executed. Here's an idea of how I'm testing it:

 @Test
    public void testSimpleGetResponseFromServerVolley() throws Exception {
        final CountDownLatch signal = new CountDownLatch(1);

        NetworkClass.NetworkListener listener = new NetworkClass.NetworkListener() {
            @Override
            public void onResponse(Response response) {
                assertThat(response != null);
                System.out.println("Got Response");
                signal.countDown();

            }

            @Override
            public void onError(Throwable error) {
                System.out.println("No Response");
                signal.countDown();
            }
        };
        NetworkClass.getResponseFromServer(null, listener);
        signal.await();
    }

此代码意外导致测试挂起并且永远无法完成.

This code unexpectedly causes the test to hang and never complete.

然而，这是我不再对情况失去理解的地方:

如果我通过 debug 运行测试并逐行执行，则测试成功执行，并收到响应.

If I run the test via debug and step through line by line, the test successfully executes, and response is received.

我认为正在发生的事情:

当我通过调试单步执行时，volley requestQueue 成功进行并发出请求，并在调用 await() 之前收到响应.

When I step through via debug, the volley requestQueue successfully carries on and makes the request, and the response is received before await() is called.

当我不通过调试单步执行时，await() 会阻塞处理所有这些的线程.

When I don't step through via debug, await() is blocking the thread which handles all of that.

关于如何处理这个问题的任何想法?

Any ideas on how I can handle this?

推荐答案

Volley 依赖 Looper.getMainLooper() 来处理其执行.当使用 RobolectricTestRunner 时，Robolectric 会对此进行模拟，因此它不会正确设置，从而导致测试失败.

Volley relies on Looper.getMainLooper() to handle its executions. When using a RobolectricTestRunner, Robolectric mocks this out and as such it will not be correctly set up, thus resulting in a failed test.

在我的具体情况下，当我使用断点时，系统实际上确实设置了主循环器，因为系统正在利用它来显示断点/调试工具.因此，这描述了我最初的问题中发现的行为背后的原因.

In my specific case, when I was using breakpoints, the system actually does set up the main looper, because the system is utilizing it to show the breakpoints / debugging tools. This thus describes the reasoning behind the behaviour found in my initial question.

现在，对于在单元测试期间使用 Volley 获得真实网络响应的解决方案，必须将执行程序更改为不使用主循环器.

Now for a solution as to getting real network responses with Volley during a unit test, the executor must be changed to not be using the main looper.

作为一个简单的解决方案，创建一个依赖于 Executor.singleThreadExecutor() 而不是 Main Looper 的请求队列.

As an easy solution, create a request queue that relies on Executor.singleThreadExecutor() instead of the Main Looper.

这就是我的意思:

    //Specific test queue that uses a singleThreadExecutor instead of the mainLooper for testing purposes.
public RequestQueue newVolleyRequestQueueForTest(final Context context) {
    File cacheDir = new File(context.getCacheDir(), "cache/volley");
    Network network = new BasicNetwork(new HurlStack());
    ResponseDelivery responseDelivery = new ExecutorDelivery(Executors.newSingleThreadExecutor());
    RequestQueue queue = new RequestQueue(new DiskBasedCache(cacheDir), network, 4, responseDelivery);
    queue.start();
    return queue;
}

然后，在测试期间将其用作 Volley 的请求队列.

Then, use that as your request queue for Volley during the tests.

这里的关键是:

ResponseDelivery responseDelivery = new ExecutorDelivery(Executors.newSingleThreadExecutor());

希望这会有所帮助！

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