Flutter Packages Weekly #13: patrol

4 min readJul 28, 2024

“Elevate Your Flutter Testing Game with patrol: The Ultimate E2E Testing Solution”

Welcome to another exciting installment of Flutter Packages Weekly! In this edition, we’re focusing on enhancing list interactions with the patrol package, a testing powerhouse that’s revolutionizing how we ensure our apps work flawlessly.

What is patrol?

Patrol is an advanced end-to-end (E2E) testing package for Flutter that takes your app testing to unprecedented heights. It’s designed to simplify the process of writing and running integration tests, ensuring your app performs seamlessly across various scenarios and user interactions.

Why Use patrol?

In the fast-paced world of app development, thorough testing is non-negotiable for delivering top-notch products. Patrol emerges as a game-changer by offering a more intuitive and feature-rich alternative to Flutter’s built-in integration_test package. Here’s why patrol should be your go-to testing tool:

Native Interaction Capabilities: Patrol allows you to interact with native UI elements, a feat not possible with standard Flutter tests.
Improved Test Readability: The package provides a more expressive API, making your tests not only easier to write but also to understand and maintain.
Advanced Widget Selection: With powerful selectors, locating and interacting with widgets in your app becomes a breeze.
Cross-Platform Consistency: Patrol works flawlessly on both iOS and Android, ensuring your tests are reliable across platforms.

Key Features of patrol

Native Element Interaction: Easily handle permission dialogs, system settings, and other native UI components.
Logical Test Organization: Group your tests for better structure and maintainability.
Custom Finder Creation: Build reusable finders for complex widget hierarchies.
Visual Verification: Capture screenshots during test execution for visual confirmation.
Flexible Timeout Configuration: Set custom timeouts for different actions to accommodate varying network conditions.

Installation Guide

Get started with patrol by adding it to your pubspec.yaml .

dev_dependencies:
  patrol: ^latest_version

To set up patrol for your project, execute:

flutter pub run patrol:init

This command will generate the necessary configuration files and example tests to jump start your testing journey.

Example Use Cases

Let’s dive into two detailed examples to showcase patrol’s capabilities:

1. User Authentication Flow

This example demonstrates how to test a complete user authentication flow, including handling native permission dialogs:

import 'package:patrol/patrol.dart';

void main() {
  patrolTest('User successfully logs in', (PatrolTester $) async {
    // Launch the app
    await $.pumpWidget(MyApp());

    // Navigate to login screen
    await $(#loginButton).tap();
    // Fill in login credentials
    await $(#emailField).enterText('user@example.com');
    await $(#passwordField).enterText('securePassword123');
    // Tap login button
    await $(#submitLogin).tap();
    // Handle biometric authentication prompt (if available)
    if (await $.native.isPermissionDialogVisible()) {
      await $.native.tap(Selector(text: 'Use Face ID'));
    }
    // Verify successful login
    await $.expectVisible(#welcomeMessage);
    await $.expectVisible(#userDashboard);
    // Check for specific user information
    expect($(#userEmail).text, equals('user@example.com'));
  });
}

2. E-commerce Product Purchase Flow

This example showcases how to test a complete e-commerce purchase flow, including interacting with a native image picker:

import 'package:patrol/patrol.dart'
void main() {
  patrolTest('User completes product purchase', (PatrolTester $) async {
    // Launch the app
    await $.pumpWidget(MyEcommerceApp());

    // Navigate to product page
    await $(#searchBar).enterText('wireless headphones');
    await $(#searchButton).tap();
    await $(#productCard).first.tap();
    // Add product to cart
    await $(#addToCartButton).tap();
    await $.expectVisible(#cartNotification);
    // Go to cart and proceed to checkout
    await $(#cartIcon).tap();
    await $(#checkoutButton).tap();
    // Fill in shipping information
    await $(#nameField).enterText('John Doe');
    await $(#addressField).enterText('123 Flutter St');
    await $(#cityField).enterText('Flutter City');
    await $(#zipCodeField).enterText('12345');
    // Select payment method
    await $(#paymentMethodDropdown).tap();
    await $(#creditCardOption).tap();
    // Enter credit card details
    await $(#cardNumberField).enterText('4111111111111111');
    await $(#expiryDateField).enterText('12/25');
    await $(#cvvField).enterText('123');
    // Upload product review image
    await $(#uploadReviewImage).tap();
    // Handle native image picker
    await $.native.tap(Selector(text: 'Choose from Gallery'));
    await $.native.tap(Selector(text: 'Recent'));
    await $.native.tap(Selector(index: 0, type: 'android.widget.ImageView'));
    // Complete purchase
    await $(#placeOrderButton).tap();
    // Verify order confirmation
    await $.expectVisible(#orderConfirmationMessage);
    await $.expectVisible(#orderNumber);
  });
}

Personal Experience

As a Flutter developer with years of experience under my belt, I can’t emphasize enough how patrol has transformed my testing approach. Before discovering patrol, testing native interactions was a significant pain point, often requiring separate test suites for iOS and Android. Patrol has allowed me to consolidate these tests, saving valuable time and ensuring more consistent behavior across platforms.

One project where patrol truly shined was a health and fitness app that required extensive permission handling and integration with native health APIs. Patrol’s native action support made it possible to create comprehensive tests that covered every aspect of the app’s functionality, from permission requests to data synchronization with health platforms. This comprehensive testing significantly reduced the number of bugs that made it to production and improved the overall user experience.

Helpful Resources

Conclusion

Patrol is an indispensable tool for Flutter developers serious about delivering high-quality, robust applications. Its ability to interact with native elements, coupled with an intuitive API, makes it a game-changer in ensuring your Flutter apps are reliable and perform consistently across different devices and scenarios.

By incorporating patrol into your testing arsenal, you’ll not only catch more bugs before they reach your users but also gain the confidence to innovate and push the boundaries of what’s possible with Flutter. The detailed examples we’ve explored demonstrate how patrol can handle complex testing scenarios with ease, from user authentication to e-commerce flows.

Give patrol a try in your next project, and experience the peace of mind that comes with thorough, efficient testing. Your future self (and your users) will thank you!

Until next week, keep coding, keep testing, and keep pushing the envelope of Flutter development!