如何编写用于Firebase通知的单元测试？

我做了以下课程来接收Firebase消息并创建通知。我已经通过将Firebase消息发送到应用程序进行了测试，并且效果很好。但是，我需要编写单元测试来测试此功能。但是我为此编写的2个单元测试都失败了。 onMessageReceived()接收RemoteMessage对象中的数据。然后，它查找键的值，type并根据键的值是0还是1，调用buildNotificationBigText()或buildNotificationBigPicture()。因此，我编写了2种测试方法。在测试方法中，我创建了一个RemoteMessage对象并将其传递给onMessageReceived()。但是，这些测试无法正常工作，并且出现以下错误：

java.lang.NullPointerException: Attempt to invoke virtual method 'void in.ac.bits_pilani.goa.ard.services.HandleFirebaseMessages.onMessageReceived(com.google.firebase.messaging.RemoteMessage)' on a null object reference
at in.ac.bits_pilani.goa.ard.activities.MainActivityTest.handleFirebaseMessageBigPicture(MainActivityTest.java:90)

java.lang.NullPointerException: Attempt to invoke virtual method 'void in.ac.bits_pilani.goa.ard.services.HandleFirebaseMessages.onMessageReceived(com.google.firebase.messaging.RemoteMessage)' on a null object reference
    at in.ac.bits_pilani.goa.ard.activities.MainActivityTest.handleFirebaseMessagesBigText(MainActivityTest.java:80)

HandleFirebaseMessages.java

public class HandleFirebaseMessages extends FirebaseMessagingService {

    /**
     * default id for notification in case specific id is not given in data.
     */
    final int default_id = 42;

    NotificationCompat.Builder builder ;

    /**
     * contains bigTitle value of data in onMessageReceived().
     */
    String bigTitle;

    /**
     * is assigned the bigSummaryText value of data in onMessageReceived().
     */
    String bigSummaryText;

    public HandleFirebaseMessages() {
    }

    /**
     * returns the bitmap image from the url given.
     * @param src image url
     * @return bitmap image at url
     */
    public static Bitmap getBitmapFromURL(final String src) {
        try {
            final URL url = new URL(src);
            final HttpURLConnection cOnnection= (HttpURLConnection) url.openConnection();
            connection.setDoInput(true);
            connection.connect();
            final InputStream input = connection.getInputStream();
            return BitmapFactory.decodeStream(input);
        } catch (final IOException e) {
            // Log exception
            Log.e("TAG", "fucked man " + e.getMessage());
            return null;
        }
    }

    /**
     * creates the notification when type is 1 or big text.
     * @param data data to be put in notification
     */
    public void buildNotificationBigText(final Map data) {
        Log.e("Tag4", "entered buildNotificationBigText");
        //final String bigTitle = data.get("bigTitle");
        final String bigSubTitle = data.get("bigSubTitle");
        //final String bigSummaryText = data.get("bigSummaryText");

        final NotificationCompat.BigTextStyle notificatiOnBigText= new NotificationCompat.BigTextStyle();

        if (bigTitle != null) {
            notificationBigText.setBigContentTitle(bigTitle);
        }
        if (bigSubTitle != null) {
            notificationBigText.bigText(bigSubTitle);
        }
        if (bigSummaryText != null) {
            notificationBigText.setSummaryText(bigSummaryText);
        }

        builder.setStyle(notificationBigText);
    }

    /**
     * creates the notification when type is 2 or big picture.
     * @param data data to be put in notification
     */
    public void buildNotificationBigPicture(final Map data) {
        Log.e("Tag3", "entered buildNotificationBigPicture");
        final String imageUrl = data.get("imageUrl");
        //final String bigSummaryText = data.get("bigSummaryText");
        //final String bigTitle = data.get("bigTitle");

        final NotificationCompat.BigPictureStyle notificatiOnBigPicture= new NotificationCompat.BigPictureStyle();
        if (imageUrl != null) {
            final Bitmap image = getBitmapFromURL(imageUrl);
            if (image != null) {
                notificationBigPicture.bigPicture(image);
            } else {
                //TODO Image is null bt url wasn;t!
            }
        }

        if (bigSummaryText != null) {
            notificationBigPicture.setSummaryText(bigSummaryText);
        }
        if (bigTitle != null) {
            notificationBigPicture.setBigContentTitle(bigTitle);
        }
        //TODO icon
        builder.setStyle(notificationBigPicture);
    }

    @Override
    public void onMessageReceived(final RemoteMessage remoteMessage) {
        super.onMessageReceived(remoteMessage);

        Log.e("Tag1", "onMessageReceived() started");
        final Map data = remoteMessage.getData();

        if (data == null) {
            return;
        }

        bigTitle = data.get("bigTitle");
        bigSummaryText = data.get("bigSummaryText");
        final String type = data.get("type");
        final String id = data.get("id");
        final String smallTitle = data.get("smallTitle");
        final String smallSubTitle = data.get("smallSubTitle");
        //final String cOntentInfo= data.get("contentInfo");
        //final String ticker = data.get("ticker");
        final String link = data.get("link");
        final String className = data.get("className");

        Log.e("Tag2", "type = " + type);

        builder = new NotificationCompat.Builder(this);

        if (type != null) {
            if (type.compareTo("1") == 0) {
                //Large Text Style corresponds to "1"
                buildNotificationBigText(data);
            } else if (type.compareTo("2") == 0) {
                //BigPicture style specific
                buildNotificationBigPicture(data);
            }
        }

        //General things to be added for any kind of notification
        if (smallTitle != null) {
            builder.setContentTitle(smallTitle);
        }
        if (smallSubTitle != null) {
            builder.setContentText(smallSubTitle);
        }

        int notificatiOnId= default_id;
        if (id != null) {
            notificatiOnId= Integer.parseInt(id);
        }
        builder.setContentIntent(addWebsiteLinkPendingIntent(notificationId, link, className));

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            builder.setCategory(Notification.CATEGORY_SOCIAL);
        }

        builder.setSmallIcon(R.drawable.ic_stat);
        builder.setColor(ContextCompat.getColor(this, R.color.colorPrimary));
        builder.setAutoCancel(true);

        final NotificationManagerCompat mNotificatiOnManager= NotificationManagerCompat.from(this);
        mNotificationManager.notify(notificationId, builder.build());

    }

    /**
     * returns the intent for the webpage or activity to open from the notification.
     * @param id notification id
     * @param link webpage link
     * @param className class for the activity to open
     * @return PendingIntent for the webpage ot activity
     */
    private PendingIntent addWebsiteLinkPendingIntent(final int id, final String link, final String className) {
        Intent intent;

        if (link != null) {
            //TODO Change to ChromeCustomTabs later
            intent = new Intent(Intent.ACTION_VIEW, Uri.parse(link));
        } else if (className != null) {
            try {
                intent = new Intent(this, Class.forName("com.csatimes.dojma." + className));
                //TODO check for page number
            } catch (final ClassNotFoundException e) {
                intent = new Intent(this, MainActivity.class);
            }
            intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
        } else {
            intent = new Intent(this, MainActivity.class);
            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NO_ANIMATION);
        }

        return PendingIntent.getActivity(
                this,
                id,
                intent,
                PendingIntent.FLAG_CANCEL_CURRENT);
    }

}

MainActivityTests.java：

  @RunWith(AndroidJUnit4.class)
public class MainActivityTest {

    private Context context;

    @Mock
    private HandleFirebaseMessages handleFirebaseMessages;

    @Rule
    public ActivityTestRule activityTestRule =
            new ActivityTestRule<>(MainActivity.class);

    @Before
    public void init() {
        cOntext= InstrumentationRegistry.getTargetContext();
        //MockitoAnnotations.initMocks(this);
        //handleFirebaseMessages = new HandleFirebaseMessages();
    }

     @Test
        public void handleFirebaseMessagesBigText() {
            HandleFirebaseMessages handleFirebaseMessages=new HandleFirebaseMessages();
            RemoteMessage remoteMessage = new RemoteMessage.Builder("token").addData("type","1").build();
            handleFirebaseMessages.onMessageReceived(remoteMessage);
            Map data = new HashMap<>() ;
            data.put("type","1");
            Mockito.verify(handleFirebaseMessages).buildNotificationBigText(data);
        }

        @Test
        public void handleFirebaseMessagesBigPicture() {
            HandleFirebaseMessages handleFirebaseMessages=new HandleFirebaseMessages();
            RemoteMessage remoteMessage = new RemoteMessage.Builder("token").addData("type","2").build();
            handleFirebaseMessages.onMessageReceived(remoteMessage);
            Map data = new HashMap<>() ;
            data.put("type","2");
            Mockito.verify(handleFirebaseMessages).buildNotificationBigPicture(data);
        }

}

Jakub Szczyg.. 5

建议在测试时限制要测试的依赖项。您可以采用不依赖FirebaseMessagingService的方式来重构代码。

例如，您可以将其提取为独立于其他类的方法（最好与不依赖FirebaseMessagingService的其他类（以及HandleFirebaseMessages中的其他方法））分离，而不是将其逻辑放在onMessageReceived（）中。它甚至可以进行结构化，使其依赖于纯Java代码，因此不需要任何工具即可运行测试。

这样，您将只测试代码，而不测试其他依赖项，这将使测试变得更加容易。

建议在测试时限制要测试的依赖项。您可以采用不依赖FirebaseMessagingService的方式来重构代码。

例如，您可以将其提取为独立于其他类的方法（最好与不依赖FirebaseMessagingService的其他类（以及HandleFirebaseMessages中的其他方法））分离，而不是将其逻辑放在onMessageReceived（）中。它甚至可以进行结构化，使其依赖于纯Java代码，因此不需要任何工具即可运行测试。

这样，您将只测试代码，而不测试其他依赖项，这将使测试变得更加容易。