用Robolectric测试隐式意图

Question

我正在开发我的Android应用程序中的一项新功能，用户可以按下按钮来启动相机，拍照并保存到应用程序的本地数据库中以供使用。这是用户单击该按钮时调用的方法及其用于创建文件的辅助方法（在Java中）：

private void capturePicture() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    // Ensure that there's a camera activity to handle the intent
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        // Create the File where the photo should go
        File photoFile = null;
        try {
            photoFile = createImageFile();
        } catch (IOException ex) {
            // Error occurred while creating the File
            ex.printStackTrace();
        }
        // Continue only if the File was successfully created
        if (photoFile != null) {
            Uri photoURI = FileProvider.getUriForFile(this,
                    "com.frischlymade.spoken.fileprovider",
                    photoFile);
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PIC);
        }
    }
}

private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpg",         /* suffix */
            storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    mCurrentImagePath = image.getAbsolutePath();
    return image;
}

我现在正在学习如何测试Android应用程序，Robolectric似乎是进行单元测试的好工具。遵循文档和首次用户测试

@Test
public void clickingLogin_shouldStartLoginActivity() {
    WelcomeActivity activity = Robolectric.setupActivity(WelcomeActivity.class);
    activity.findViewById(R.id.login).performClick();

    Intent expectedIntent = new Intent(activity, LoginActivity.class);
    Intent actual = shadowOf(RuntimeEnvironment.application).getNextStartedActivity();
    assertEquals(expectedIntent.getComponent(), actual.getComponent());
}

我为我的方法编写了此测试（在Kotlin中）：

@Test fun clickingTake_shouldStartCamera() {
    val activity: AddCategoryActivity = Robolectric.setupActivity(AddCategoryActivity::class.java)
    activity.findViewById<MaterialButton>(R.id.item_take_pic_btn).performClick()

    val expected = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
    val actual   = shadowOf(RuntimeEnvironment.application).nextStartedActivity
    assertEquals(expected.component, actual.component)
}

但是，当我运行测试时，测试失败，结果为“ actual不能为null”。所以我知道出了点问题，与示例的主要区别是我在显式上使用了隐式意图。我也正在开始暗示结果的意图，这也可能会影响事物。我不知道为什么我得到错误。我如何修改它以适用于隐式意图？还是我应该以其他方式这样做？