Question

我有一个单元测试，用于测试将文件上传到GCP存储。这是上传文件的代码。

@Override
public boolean upload(StorageConfiguration storageConfiguration, File file) throws MetaFeedException {
    // get google storage connection.
    Optional<Storage> storage = getStorageConnection(storageConfiguration.getJsonCredentialFilePath());

    // if GCP storage is empty, return empty.
    if (!storage.isPresent()) {
        throw new MetaFeedException("Failed to establish connection with GCP storage");
    }

    // upload blob with given file content
    BlobId blobId = BlobId.of(storageConfiguration.getBucketName(),
            storageConfiguration.getBucketPath().concat(file.getName()));
    BlobInfo blobInfo = BlobInfo.newBuilder(blobId).setContentType(storageConfiguration.getContentType()).build();
    try {
        return storage.get().create(blobInfo, Files.readAllBytes(Paths.get(file.getAbsolutePath()))).exists();
    } catch (Exception e) {
        throw new MetaFeedException("Error occurred while uploading file.", e);
    }
}

在单元测试中，我已经做了类似的事情，

@Test
public void should_upload_file_to_gcp_with_given_data() throws Exception {
    File tempFile = File.createTempFile("file-name", "1");

    StorageConfiguration storageConfiguration = new StorageConfiguration();
    storageConfiguration.setBucketName("sample-bucket");
    storageConfiguration.setBucketPath("ff/");
    storageConfiguration.setJsonCredentialFilePath("json-credentials");
    storageConfiguration.setContentType("text/plain");

    StorageOptions defaultInstance = mock(StorageOptions.class);
    Storage mockStorage = spy(Storage.class);

    when(defaultInstance.getService()).thenReturn(mockStorage);

    BlobId blobId = BlobId.of(storageConfiguration.getBucketName(), storageConfiguration.getBucketPath().concat(tempFile.getName()));
    BlobInfo blobInfo = BlobInfo.newBuilder(blobId).setContentType(storageConfiguration.getContentType()).build();

    doNothing().when(mockStorage).create(blobInfo, Files.readAllBytes(Paths.get(tempFile.getAbsolutePath())));

    boolean upload = gcpStorageManager.upload(storageConfiguration, tempFile);
    Assert.assertTrue(upload);
}

我想做的是防止调用create()方法。我的观点是，我不想将其真正上传到GCP，因为这是一项测试。所以我尝试了如上所述。但是我出错了，

org.mockito.exceptions.base.MockitoException: 
Only void methods can doNothing()!
Example of correct use of doNothing():
    doNothing().
    doThrow(new RuntimeException())
    .when(mock).someVoidMethod();
 Above means:
someVoidMethod() does nothing the 1st time but throws an exception 
the 2nd time is called

更新

Optional<Storage> storage;
    try {
        //connect with the json key file if the key path is not empty
        if (StringUtils.isNotEmpty(jsonCredentialFilePath) && Files.exists(Paths.get(jsonCredentialFilePath))) {
            storage = Optional.ofNullable(StorageOptions.newBuilder()
                    .setCredentials(ServiceAccountCredentials.fromStream(new FileInputStream(jsonCredentialFilePath)))
                    .build().getService());
        } else {
            // if no json key file provided connect to storage without key file.
            storage = Optional.ofNullable(StorageOptions.getDefaultInstance().getService());
        }
    } catch (Exception e) {
        throw new MetaFeedException("Error occurred while connecting to GCP storage", e);
    }

    return storage;

是否有一种方法可以解决此测试，以将文件上传到GCP？

Answer 1

错误消息中描述了实际的问题：Only void methods can doNothing()

create()方法不是无效的，因此您不能使用doNoting()对其进行模拟，因此必须使用doReturn。您可以返回Blob的模型：

Blob mockBlob = mock(Blob.class);
when(mockBlob.exists()).thenReturn(true);
doReturn(mockBlob).when(mockStorage).create(blobInfo, Files.readAllBytes(Paths.get(tempFile.getAbsolutePath())));

这是第一个错误。第二，看起来您没有将间谍对象注入被测对象。您的方法getStorageConnection()将在您调用Storage时创建一个新实例，并且不考虑该间谍对象。因此，您在模拟StorageOptions.class，但是StorageOptions.getDefaultInstance()方法对这个模拟对象一无所知。

因此，在这里我可以看到两种解决问题的方法。第一个，对我来说，更可取的是将依赖注入到方法或类中。对方法的依赖注入：

@Override
public boolean upload(Storage storage, File file) throws MetaFeedException {

但是，事实并非如此，只要您的方法覆盖了某些接口（如我所假设）。因此，您可以将方法getStorageConnection移动到单独的类StorageProvider并将其实例注入您的类，然后在测试中您可以模拟StorageProvider来返回{{1 spy中的}}。在上传方法中，您将调用：

Storage

第二条路径（这是解决方法）是使方法Optional<Storage> storage = storageProvider.getStorageConnection(storageConfiguration.getJsonCredentialFilePath());受保护，并在测试中对其进行重写以返回被监视的对象。在您的测试中：

getStorageConnection

Answer 2

我遇到以下问题：我有一个返回Page <...>的方法，但是我只能在void方法上使用doNothing（），所以修复很容易：

    @Override
    public Page<ThreadServiceModel> findAll(Pageable pageable) {
        return this.findAll(ThreadServiceModel.class, pageable);
    }

然后我们开始：

        //Will fail and the actualy findAll will be invoked:
        when(this.threadServices.findAll(ThreadServiceModel.class,pageable)).thenReturn(null);

        //Will fail ,cuz you cannot call doNothing() on something that returns values

        doNothing().when(this.threadServices).findAll(ThreadServiceModel.class,pageable);

        //This is the solution ,and when you use doReturn() the actual method will be NOT invoked,
        //+In my case i dont need value , but if i want I cant use...
        doReturn(null).when(this.threadServices).findAll(ThreadServiceModel.class,pageable);

因此解决方案很简单，请在我向您展示的代码上使用最后一种方法：）

Mockito中具有doNothing（）的非无效方法？

2 个答案: