V-Techhub #3: TESTING IN MOBILE AND HOW TO TEST USING FLUTTER

Ruyk – Flutter Developer

It’s the third week of the month again, folks! Which means more sharing from our expert at Vinova. This May, we continue the topic of last month’s Flutter platform to build mobile apps.

But… building a great Flutter app is only half the battle! This week, we focused on the crucial aspect of mobile testing with Flutter. Join Ruyk as he dives into effective testing strategies and best practices to guarantee the quality and performance of your Flutter applications.

Why do we need testing in Flutter?

Do you know that testing is an indispensable aspect of software development? Yes! It’s estimated that 43% of developers are involved in testing, indicating that testing is a significant part of their duties.

In Flutter development, testing is crucial in delivering working and bug-free applications across multiple platforms. With Flutter’s support for testing frameworks and tools, developers can implement various testing methodologies and strategies to validate their code efficiently.

Understanding Testing in Flutter

To me, testing in Flutter can mean going through many steps of testing to verify the functionality, behavior, and performance of Flutter applications. At its core, testing in Flutter involves writing test cases to validate individual components, features, and user interactions within the app. 

Flutter provides built-in support for testing through packages like flutter_test, enabling developers to seamlessly write unit tests, widget tests, and integration tests. Understanding the different types of testing and their purposes is essential to make sure every part of your app works, behaves and performs just like it’s supposed to!

Types of Testing in Flutter

To ensure the quality and reliability of Flutter applications, developers should leverage various testing methodologies. Here, we explore the different types of testing available in Flutter:

• Unit testing: test a single method, class, or function. This testing aims to verify the correctness of a function, individual units, or application functions in isolation, often focusing on small atomic units of code. In Flutter, unit tests are written using the ‘flutter_test’ package, which allows developers to test pure Dart code without interacting with the UI.
• Widget testing: tests a single widget, or component testing, focuses on testing Flutter widgets and their interactions. Widget tests validate the UI components’ behavior and appearance under different scenarios, such as user input or state changes. Flutter provides the ‘flutter_test’ package for writing widget tests and utilities like WidgetTester for simulating user interactions. This testing aims to verify that a widget looks and works as expected.
• Integration Testing: tests a complete app. Integration testing involves testing the interaction between different application modules, components, or layers. In Flutter, integration tests validate the end-to-end functionality of the app by simulating user interactions across multiple screens or widgets. Flutter’s integration testing framework allows developers to write tests that interact with the app’s UI elements and verify the application’s overall behavior.

6 Basic Steps to Unit Testing in Flutter

Unit tests verify the behavior of individual functions, methods, or classes. The test package offers essential tools for writing unit tests, while flutter_test provides extra utilities for widget testing. Here’s a recipe showcasing the test package’s core features:

1. Add the test or flutter_test dependency
2. Create a test file.
3. Create a class to test.
4. Write a test for our class.
5. Combine multiple tests in a group.
6. Run the tests.

For more specifically with each step above, you can see here

Best Practices for Testing in Flutter

• Write Testable Code: Designing code with testability in mind facilitates writing comprehensive test suites and ensures the application’s logic can be easily tested.
• Use Mocking and Dependency Injection: Utilize mocking frameworks and dependency injection techniques to isolate dependencies and simulate external interactions during testing, improving test reliability and maintainability.
• Automate Testing Workflow: Integrate testing into the development workflow and automate test execution using continuous integration (CI) tools like Jenkins, Travis CI, or GitHub Actions to catch regressions early and ensure code quality.
• Follow Testing Pyramid Principles: Adhere to the pyramid principles by prioritizing unit tests over widget and integration tests, focusing on testing individual units extensively before moving on to higher-level tests.
• Regularly Refactor and Update Tests: Refactor test code regularly to keep it maintainable and up-to-date with changes in the application codebase, ensuring that tests remain relevant and effective over time.

Conclusion

Testing is a fundamental aspect of Flutter development, ensuring application reliability, stability, and quality. Flutter offers various testing approaches, including unit testing, widget testing, and integration testing, allowing developers to create comprehensive test suites that effectively validate their code.

By following best practices, such as writing testable code, utilizing mocking and dependency injection, automating the testing workflow, and adhering to testing pyramid principles, developers can streamline the process and significantly enhance the overall quality of Flutter applications.  Embracing a robust testing culture ultimately leads to more reliable code, fostering confidence in the app’s behavior for a better user experience and increased developer productivity.