Automating Tests with Flutter TestLab

Ensuring the quality and reliability of mobile applications is paramount. For Flutter apps, automating tests is essential for catching bugs early and maintaining a robust codebase. Flutter TestLab provides a cloud-based infrastructure to test your Flutter apps across a wide variety of real and virtual devices. This post will guide you through automating tests with Flutter TestLab, enhancing your app’s reliability.

What is Flutter TestLab?

Flutter TestLab is part of the Firebase Test Lab and provides cloud-based infrastructure for testing Android and iOS apps, including Flutter apps. It allows developers to run automated UI tests, unit tests, and integration tests on a variety of device configurations and screen sizes, providing insights into potential issues on different hardware and OS versions.

Why Automate Tests with Flutter TestLab?

• Broad Device Coverage: Test your app on a vast array of virtual and physical devices without needing to own or configure them.
• Automated Testing: Execute UI tests and other automated tests to detect issues early in the development lifecycle.
• Parallel Testing: Run tests concurrently on multiple devices, drastically reducing testing time.
• Detailed Reporting: Access detailed reports with logs, screenshots, and videos, facilitating quicker debugging.
• Reduced Manual Testing: Automate repetitive tasks to free up resources and increase test coverage.

Prerequisites

Before diving into automating tests with Flutter TestLab, ensure you have the following prerequisites in place:

• Flutter Environment: A correctly set up Flutter development environment.
• Firebase Project: A Firebase project associated with your Flutter app.
• Firebase CLI: The Firebase command-line tool installed and configured.
• Google Cloud SDK: The Google Cloud SDK installed and authorized.
• Appropriate Tests: Flutter UI tests (e.g., using Flutter Driver or Patrol) or unit/integration tests.

Step-by-Step Guide to Automating Tests with Flutter TestLab

Step 1: Set Up Firebase Project

If you haven’t already, create a Firebase project in the Firebase console:

1. Go to the Firebase Console.
2. Click “Add project”.
3. Enter your project name and follow the prompts to set up your project.
4. Associate your Flutter app with the Firebase project.

Step 2: Install and Configure Firebase CLI

Install the Firebase CLI globally using npm:

npm install -g firebase-tools

Log in to Firebase using the CLI:

firebase login

Initialize Firebase in your Flutter project directory:

firebase init

Select “Test Lab” during the initialization process and configure as needed.

Step 3: Set Up Google Cloud SDK

Install the Google Cloud SDK. Follow the installation instructions specific to your operating system from the official Google Cloud SDK documentation.

After installing, initialize the Cloud SDK and authenticate your account:

gcloud init

Set the active project to your Firebase project:

gcloud config set project YOUR_FIREBASE_PROJECT_ID

Step 4: Write Flutter Tests

Create your Flutter tests. For UI tests, you can use flutter_driver or patrol. Here’s an example using flutter_driver:

Example UI Test with flutter_driver

First, add flutter_driver and test to your dev_dependencies in pubspec.yaml:

dev_dependencies:
  flutter_test:
    sdk: flutter
  flutter_driver:
    sdk: flutter
  test: any

Create a test file (e.g., test_driver/app.dart):

import 'package:flutter_driver/driver_extension.dart';
import 'package:flutter/material.dart';
void main() {
  enableFlutterDriverExtension();
  runApp(MaterialApp(home: Scaffold(body: Center(child: Text('Running Flutter Driver Tests')),),));
}

Create a test file (e.g., test_driver/app_test.dart):

import 'package:flutter_driver/flutter_driver.dart';
import 'package:test/test.dart';
void main() {
  group('Flutter Driver Example', () {
    late FlutterDriver driver;
    setUpAll(() async {
      driver = await FlutterDriver.connect();
    });
    tearDownAll(() async {
      if (driver != null) {
        await driver.close();
      }
    });
    test('verify app launches', () async {
      final timeline = await driver.traceAction(() async {
        // Replace this with your test logic.  This example just waits
        // a bit.
        await Future.delayed(Duration(seconds: 1));
      });
    });
  });
}

Step 5: Build Your App

Build your Flutter app for testing:

flutter build apk

Or for iOS:

flutter build ios

You can also build an app bundle:

flutter build appbundle

Step 6: Run Tests on Flutter TestLab

Use the Firebase CLI to run your tests on Flutter TestLab.

For Android:

firebase test lab android run \\
  --app build/app/outputs/apk/release/app-release.apk \\
  --device model=redfin,version=30 \\
  --test test_driver/app_test.dart

Customize the device parameters according to your testing requirements. Available parameters include:

• model: Device model (e.g., Pixel4, Nexus5X)
• version: Android API level (e.g., 29, 30)
• locale: Device locale (e.g., en_US, fr_FR)
• orientation: Screen orientation (e.g., portrait, landscape)

For iOS:

You need to build an .ipa file and use a simulator. Please check the official Firebase documentation for more accurate instructions for iOS tests since configurations may require more parameters related to provisioning profiles and certificates.

Step 7: Review Test Results

Once the tests are running, Firebase Test Lab will provide detailed reports. You can access them from the Firebase Console:

1. Go to the Firebase Console.
2. Select your project.
3. Navigate to “Test Lab” in the left-hand menu.
4. View the test results, including logs, screenshots, and videos of the test execution.

Example: Automating Tests with Patrol

Patrol is an alternative UI testing framework that provides more control over UI elements and native features. Here’s how to set it up.

Step 1: Add Patrol Dependencies

In your pubspec.yaml:

dev_dependencies:
  patrol: ^3.0.0

Step 2: Write Patrol Tests

Create a Patrol test (e.g., integration_test/app_test.dart):

import 'package:flutter_test/flutter_test.dart';
import 'package:patrol/patrol.dart';

void main() {
  patrolTest('Counter increments on button tap', ($) async {
    await $.pumpWidgetAndSettle(MyApp());

    await $(#incrementButton).tap();
    expect($(#counterText).text, equals('1'));
  });
}

Step 3: Run Patrol Tests on Firebase Test Lab

Follow the Patrol documentation to configure your project for Firebase Test Lab. This often involves building the app with specific configurations to allow Patrol to interact with it during testing.

patrol drive --target integration_test/app_test.dart --flavor prod --dart-define FLAVOR=prod

Best Practices for Flutter TestLab Automation

• Regular Testing: Incorporate automated testing into your CI/CD pipeline for continuous validation.
• Diversify Devices: Test on a wide variety of devices and Android/iOS versions to ensure compatibility.
• Comprehensive Test Coverage: Write tests that cover various aspects of your app, including UI elements, navigation, and critical functionality.
• Review Test Reports: Regularly analyze test reports to identify and address issues promptly.
• Use Mock Data: For integration tests, use mock data to isolate the app from external dependencies and ensure test reliability.

Conclusion

Automating tests with Flutter TestLab is a crucial part of developing robust and reliable Flutter applications. By leveraging Flutter TestLab, you can ensure your app functions correctly across a broad spectrum of devices, catch issues early, and reduce the time and resources spent on manual testing. Embrace automated testing as part of your development process to deliver high-quality Flutter apps with confidence.