6 Best Practices for Rock-Solid Frontend Component Testing

Imagine launching a web application, and users start experiencing issues like inaccessible forms and pages, broken buttons, and inconsistent interfaces. This scenario can frustrate users and damage your business reputation.

Testing front-end components is essential for delivering high-quality web applications. Testing your components ensures that they function properly, are accessible to everyone, and have a consistent user interface.

Best practices make testing efficient and effective by providing an organized approach and streamlining activities to improve software quality.

If you're a software tester responsible for testing frontend components, this article outlines key best practices to guide you.

Choose the right type of test for your project

Before starting the testing process, you need to decide on the appropriate type of test to use to cover different aspects of your application.

There are various types of testing available for frontend components, so how do you know when to use each of them? Let’s look into that and discuss scenarios that are best suited for each of these testing types.

• Unit Testing: Unit testing is the foundation for testing front-end components. It involves checking individual components independently to ensure they work as expected. It is mostly performed by developers.

  For instance, if you only need to verify that a button component renders correctly and triggers the appropriate function when clicked, unit testing is the right approach. Similarly, you would use unit testing to ensure a function correctly calculates the total price of products.

• Integration Testing: Integration testing checks how multiple components work together to ensure they interact correctly and ensure that data flows properly.

  For instance, if you want to test that a form component interacts properly with its child input component and submits users’ data correctly, integration testing would be the right type of test to perform.

• End-to-End (E2E) Testing: End-to-end testing checks the entire application workflow from start to finish. It is best for validating user journeys and the app's overall behavior.

  If you want to test the full functionality of an e-commerce shopping cart, you’ll perform end-to-end testing by adding items to the cart, removing items and checking out. Similarly, if you want to make sure the authentication provider is working as it should, you’ll also perform end-to-end testing. You’ll test the entire user registration process by filling out the registration form, receiving a confirmation email, logging in, and then logging out.

Understanding when to use each of these types of tests allows you to develop a comprehensive testing plan that addresses all necessary scenarios.

Now that you know how to choose the right type of test, you’ll learn how to balance testing strategy to avoid leaning too much on any one testing method.

Maintain a balanced testing strategy

End-to-End testing involves testing the whole application from the end user’s perspective, i.e., testing the complete application from start to finish.

Over-reliance on end-to-end tests can lead to several issues, such as:

• E2E tests are prone to false positives and negatives, reducing their reliability.
• It can be time-consuming, especially for complex software.
• It can be hard to maintain if you’re dealing with large cases of frequently changing E2E tests.

To achieve and maintain a balanced testing strategy, allocate your testing efforts effectively across unit, integration, and end-to-end (E2E) tests. Here's how you can do that:

• Follow the testing pyramid by first ensuring that most of your tests are unit tests, as this can help you quickly identify and fix problems at their source. Next, utilize integration tests to validate how different components work together, as this will help you catch issues that unit tests might miss. E2E tests should be saved for high-risk areas and critical user journeys, like end-to-end validation, since they are resource-intensive.
• Use mocking and stubbing in unit and integration tests to isolate components, reducing complexity and increasing execution speed.

This approach ensures thorough testing while maintaining efficiency and reliability.

Now, let's focus on how you can maintain UI consistency by using visual regression testing to detect any unexpected changes.

Use visual regression testing to catch changes in UI

Since you’re testing the frontend part of the web application — the part that users see, it’s important that the UI is consistent. UI consistency here refers to the uniformity of design elements such as the font, colors, button styles and layouts throughout the application.

Visual regression testing detects changes in your app's appearance by comparing snapshots before and after code changes. This ensures that the UI remains consistent and catches design issues that functional tests might miss, reducing the risk of visual bugs.

Recommended tools include Applitools, which uses AI to automate visual testing, and Percy, to get visual insights into code change.

After ensuring UI consistency, focus on making your components accessible to all users to improve usability.

Test for accessibility

Ensuring that your components are accessible to all users is not just a best practice; it's a necessity. Accessibility testing involves testing to ensure your software is easily accessible to everyone, including people with disabilities.

Some advanced accessibility testing strategies you can implement:

• Automated tools like Axe and WAVE catch common issues but may miss some details. Combine automation for repetitive tasks with manual testing for things like keyboard accessibility and accurate alt text descriptions.
• Using keyboard navigation to make all interactive features accessible to people who may not be able to use a mouse.
• Test your application with screen readers to ensure that the content is understandable.
• Consider the challenges of dynamic content and complex UI elements, like custom dropdowns that may not be immediately accessible. Address them by ensuring that ARIA (Accessible Rich Internet Applications) attributes are properly implemented.

By including accessibility testing in your process, you can ensure that everyone can use your application.

Write maintainable and reusable test code

Structuring your test code for reusability and maintainability makes it efficient, easy to update, and reduces duplication, all of which improves debugging and consistency.

Quick tips for writing clean test cases:

• Organize your tests into small, reusable modules.
• Reuse common test logic to avoid duplication
• Use descriptive test names to make the code self-explanatory.

Following these practices helps you create a maintainable and scalable test suite.

Continuously integrate and automate your tests

Integrating and automating tests into your CI/CD pipeline ensures that they run automatically with every code change, speeding up development, detecting errors early, and maintaining consistent code quality.

Tools for test automation include Jenkins, which can be set up to run tests in parallel across multiple nodes, reducing the time it takes to validate code changes in large codebases. Another tool is GitHub Actions, which supports matrix builds that allow you to run tests across different environments (e.g., operating systems and multiple browser versions).

Strategies for test automation include:

1. Integrate automated tests early to catch issues sooner.
2. Use unit, integration, and end-to-end tests.
3. Run tests in parallel to speed up the testing process.
4. Continuously monitor test results and performance.

Continuously integrating and automating your tests can help you improve the reliability and quality of your web applications.

Each of these best practices helps make the testing process more effective and efficient, ensuring high-quality front-end components.

Conclusion

You can achieve an efficient testing process by following best practices such as choosing the appropriate tests, balancing your strategy, using visual regression testing, ensuring accessibility, creating maintainable code, and automating tests.

These practices help you deliver a better user experience and keep your application consistent and reliable.