监视异步任务不起作用

Question

我正在测试一个AsyncTask。我想存根一个HttpURLConnection以返回我的模拟对象。这就是我的做法(PackageDownloader代表一个AsyncTask(：

 ...
 PackageDownloader packageDownloader = new PackageDownloader();
 packageDownloader.setParameters(URL, downloadFolder, downloadProgressCallback);
 PackageDownloader mPackageDownloader = spy(packageDownloader);
 HttpURLConnection connectionMock = Mockito.mock(HttpURLConnection.class);
 doReturn(0).when(connectionMock).getContentLength();
 doReturn(connectionMock).when(mPackageDownloader).createConnection(Mockito.any(URL.class));
 mPackageDownloader.execute();
 mPackageDownloader.get();

这是PackageDownloader：

public HttpURLConnection createConnection(URL url) throws IOException {
    HttpURLConnection connection;
    connection = (HttpURLConnection) url.openConnection();
    return connection;
}
@Override
protected DownloadResult doInBackground(Void... params) {
    HttpURLConnection connection;
    URL downloadUrl = new URL(downloadUrlString);
    connection = createConnection(downloadUrl);
    long totalBytes = connection.getContentLength();
    ...

在这里，createConnection 返回真实的，而不是模拟的对象，我不知道为什么。

Answer 1

好吧，我已经找到了一个解决方案，尽管还没有找到为什么它会如此工作的解释。没有任何效果的原因是doInBackground方法是异步的，我假设，所以我不得不通过反射直接调用它，如下所示：

 Method method = mPackageDownloader.getClass().getMethod("doInBackground", Void[].class);
 method.invoke(mPackageDownloader, new Void[] {null});

Answer 2

您可以使用 robolectric 来测试异步任务而不是反射。遵循ShadowApplication.runBackgroundTasks()应调用doInBackground()方法。

@RunWith(RobolectricTestRunner.class)
public class AcknowledgeAppRemovedTaskTest {
    @Test
    public void execute_shouldOpenInputStreamOfConnection() throws IOException {
        DownloadTask spy = spy(new DownloadTask());
        HttpURLConnection connectionMock = mock(HttpURLConnection.class);
        doReturn(connectionMock).when(spy).createConnection(any(URL.class));
        spy.execute();
        ShadowApplication.runBackgroundTasks();
        verify(connectionMock).getInputStream();
    }
}

class DownloadTask extends AsyncTask<Void, Void, Void> {}
    public HttpURLConnection createConnection(URL url) throws IOException {
        return (HttpURLConnection) url.openConnection();
    }
    @Override
    protected Void doInBackground(Void... voids) {
        try {
            HttpURLConnection urlConnection = createConnection(new URL("https://www.google.com/"));
            urlConnection.getInputStream();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

https://github.com/robolectric/robolectric/blob/master/robolectric/src/test/java/org/robolectric/shadows/ShadowAsyncTaskTest.java

https://groups.google.com/forum/#!topic/mockito/mqF21aqTi5g