During the development and maintenance of an application, it is essential to ensure that added functionalities and modifications achieve the intended goals while avoiding the emergence of errors or a decrease in performance.

For this, it is crucial to implement a solid and efficient testing framework. In this article, we will explore key aspects to consider when working with React Native and Expo in the realm of mobile application testing.

We suggest reviewing our articles Why should you start testing?, The test types you need, What is TDD? if you are just starting with testing.

Build Process

An agile build process is essential for success in application development, as it allows adapting to changes, testing new features, and releasing updates securely. Additionally, obtaining early feedback helps identify performance issues and resolve them before reaching production.

Automatically incorporating tests into the build process can pose certain challenges, such as test rendering, dependency management, waiting times, and compatibility with CI/CD tools.

Despite these challenges, having an efficient and agile build system that facilitates development and test execution is essential. It is advised to keep dependencies up to date and follow the guidelines provided by the testing tools used.

Emulators

Emulators are an excellent option for testing our applications in a controlled environment without depending on physical devices. We can test our applications on iOS and Android emulators easily without installing any additional software. If you are not familiar with running your application on emulators, you can follow the guide provided by Expo.

Physical Devices

It is essential to perform tests on physical devices to ensure our application's compatibility on different platforms, especially on Android, which has a wide variety of devices.

In addition, it is crucial to monitor the use of hardware resources, such as the camera, GPS, and accelerometer, as well as identify performance issues on lower-capacity devices to ensure an optimal user experience. If you are not familiar with running your application on physical devices, you can follow the official documentation.

Automated Testing

Integrating automated testing into our build process and continuous delivery is essential to ensure our application meets the expected quality and performance standards.

By running tests automatically, we can ensure that our application works correctly in different scenarios and prevent issues that could affect users.

It is important to ensure that tests are defined correctly and cover all relevant aspects of the application. This way, we can have greater confidence in the stability of the release and scale safely without worrying about unexpected errors in production.

Tools

Jest

The Jest testing framework is highly popular and seamlessly integrates with React Native and Expo. It allows for unit, integration, and snapshot testing.

Jest offers a variety of advantages, including support for different test types, easy configuration, module mocking, a watcher that runs tests on save, code coverage reports, and support for asynchronous tests.

React Native Testing Library

RNTL is a testing library for React Native, inspired by react-testing-library, allowing us to render our components in our tests.

It is a great option for testing React Native components. Its focus on integration testing and accessibility testing makes it ideal for implementing comprehensive tests that ensure a great user experience.

Detox

Detox is an automated testing library for React Native that allows for functional testing on iOS and Android emulators and physical devices.

The main advantage of Detox is its ability to simulate real user interactions with the application, such as gestures, button presses, and keyboard input. This makes tests more accurate and similar to the actual end-user experience.

In addition, Detox automates tests involving application navigation, camera interaction, and other hardware functions. This is particularly useful for applications that heavily rely on mobile device resources.

Conclusion

Tests are essential for the development and maintenance of projects. To be effective, it is necessary to have the right tools and solid knowledge of the subject.

In this article, we covered the most important aspects of implementing a testing framework for mobile applications.

Remember that test automation improves quality and reduces the costs and time spent on manual testing.

Make sure to keep your dependencies up to date, follow the guides of the tools you use, automate your tests, and you will achieve a new level of quality in your applications.

Good luck with the development of your applications!