在 Mockito 中使用 doNothing() 的非空方法？

Question

我有一个单元测试来测试将文件上传到 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);
    }
}

在我的单元测试中，我做了这样的事情，

@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);
}

我要做的是防止调用该create()方法。我的观点是我不想真正上传到 GCP，因为这是一个测试。所以我尝试了上面的方法。但我有一个错误，

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;

有没有办法修复这个将文件上传到 GCP 的测试？

Answer 1

我遇到了以下问题：我有一个返回 Page<...> 的方法，但我只能在 void 方法上使用 doNothing() ，因此修复很容易：

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

现在我们开始：

        //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);

所以解决方案很简单，使用我向您展示的代码的最后一种方法:)