Introduction to Frontend Testing: Best Practices and Tools
Tags: frontend, testing, javascript, ux
Published: 2023-07-21 12:27:28

**_Frontend testing_** is the process of testing the user interface (UI) of a web application, website or mobile application. **_The purpose of frontend testing_** is to ensure that the UI works correctly and meets the requirements described in the documentation, specifications or design requirements. In this article, I offer you to familiarise yourselves with the best practices and tools that significantly facilitate this painstaking procedure. *But first and foremost, let’s draw a line between frontend and backend testing, and discuss the importance of frontend testing in modern engineering.*

## Indispensability of Frontend Testing

**The main difference** between frontend (client-side) and backend (server-side) testing is that frontend testing focuses on the user interface (UI), while backend testing focuses on the server-side logic and functionality.

Frontend testing includes testing for responsiveness, accessibility, performance, and other UI-related issues, whereas backend testing involves testing database connectivity, API endpoints, error handling, and other backend-related aspects.

Although both types of testing are vitally important, frontend testing is often considered to be a more critical dimension of web development as it directly impacts user experience. In general, frontend testing helps us:

1. _**Ensure quality.**_ It helps us guarantee that both the UI and UX meet the expectations of the end-user. In other words, it allows software engineers to identify and fix issues before they become visible to users.

2. _**Reduce risks.**_ Frontend tests assist in mitigating risks associated with development, such as security vulnerabilities, performance issues, and compatibility with different browsers and devices.

3. _**Build confidence.**_ Frontend developers can build confidence in their work by knowing that their code passes tests and lives up to the expectations. Eventually, this can lead to increased productivity and reduced stress levels.

4. _**Improve efficiency.**_ It’s no secret that frontend test automation can improve efficiency in the development process by reducing manual testing and duplication of effort.

5. _**Enhance UX.**_ Frontend testing can help developers identify issues that affect the UX, such as broken links, slow loading times, or broken forms, and promptly fix all of them.

So, as you might understand, any frontend developer should prioritise frontend testing as part of their development process to secure the success of their groundbreaking projects.

## Types of Frontend Testing

Actually, there are several types of frontend testing, each with its own purpose and approach:

1. _**Unit tests:**_ These tests focus on individual components or modules of the frontend codebase, typically written in JavaScript or TypeScript. They verify that the code behaves as expected and that there are no errors or runtime exceptions.

2. _**Component tests:**_ These are tests that concentrate on specific components of the frontend application, such as React components or Angular directives. They verify the behaviour of those components and ensure that they work correctly with the rest of the application.

3. _**E2E (end-to-end) tests:**_ These focus on the entire frontend application and affirm that it behaves correctly when users interact with it. They may also involve automation of browser interactions or use of tools like Selenium.

4. _**Accessibility tests:**_ Tests of this kind reaffirm that the frontend application is accessible to people with disabilities, such as blindness or motor impairments. They check for compliance with standards like WCAG 2.0 and Section 508.

5. _**Performance tests:**_ Such tests measure the performance of the frontend application by gauging its load time, resource usage, and responsiveness. They can help detect bottlenecks or inefficiencies in the codebase and suggest ways to improve performance.

6. _**Security tests:**_ These tests ensure that the frontend code is secure and does not contain vulnerabilities or security risks. They may include testing for cross-site scripting (XSS), SQL injection, or other security issues.
 
7. _**Load testing:**_ Finally, load tests simulate the load on the frontend application to identify any performance problems under heavy traffic conditions. Additionally, they can help predict how the application will perform in real-world conditions

## Best Frontend Practices

Now that we’ve covered the basics of frontend testing, it’s time to start discussing the most _**beneficial frontend practices.**_ Some of them may seem basic and too obvious, but many frontend developers today tend to ignore them:

1. _**Writing clear and concise test cases.**_ You, as a frontend developer, must ensure that your test cases are well written and clearly define what you want to test. This will make your tests easier to understand and maintain.

2. _**Not striving for the entire code coverage.**_ This means that instead of trying to cover every line of code with tests, developers should focus on testing the most important and critical blocks of code. This approach can help reduce the time and resources required to test the code, while still ensuring that the most important functionality is covered.

3. _**Using a test automation framework.**_ Automating your frontend testing can make the entire process faster and more reliable. There are many frameworks such as Jest, Cypress and Puppeteer that can help you automate your tests.

4. _**Run automated tests regularly.**_ This will help you catch bugs and problems as early as possible. Most importantly, it can save you time and money in the long run.

5. _**Documenting your test results.**_ This common yet highly efficient practice helps you understand what went wrong and what needs to be fixed. Besides, it can aid other developers understand why certain changes were made.

6. _**Conducting deterministic testing.**_ It is a type of testing that aims to ensure that a software system behaves in a predictable way. When performing deterministic testing, the same test is run multiple times with the same inputs, and the same outputs are expected each time. By performing deterministic testing, you can reduce the risk of introducing unexpected errors or behaviour into your system and improve its overall quality and performance.

7. _**Refusing from testing internals.**_ This concept presupposes the idea of not testing the internal workings of a component or module, but rather focus on its external behaviour and interactions with other components. Such an approach helps keep the frontend codebase clean and maintainable by avoiding the need to test code that is not directly related to user interaction.   

## Best Frontend Testing Tools

_**It is self-explanatory that none of the aforementioned practices can be brought to life without using the testing tools I’m going to talk about in this section.**_ Here is _my personal_ list of the best frontend testing tools:

1) _**Selenium**_ – an open-source web automation tool that allows you to automate and interact with web applications using programming languages such as Java, Python or C#. It provides a playback tool for authoring functional tests across most of the web browsers. Selenium has one of the largest communities within the industry and is widely used in frontend testing. 

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/1lgt5d9iuwdzigx6c63q.png) Source: _Blazemeter_

2) _**Cypress**_ – a JavaScript-based test automation framework designed to make it easy to write, maintain and scale tests for web applications. Cypress uses a declarative and test-driven approach to test automation, which means that you write tests by defining what you want the application to do, rather than how to achieve it. Cypress has a number of features that make it an attractive choice for frontend test automation. It comes with a built-in test runner and support for manipulating the Document Object Model, making it possible for you to share tests across various projects and teams. On top of that, Cypress offers a plugin architecture that allows you to extend the framework with custom commands, assertions, and more.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/idrle0r3yc933o706paw.png) _Source: Cypress.io_

3) _**Applitools**_ – a tool for automating web application testing, specifically for frontend testing. It is based on Selenium and allows you to write tests in JavaScript, but also has its own test runner and a library of pre-built commands. Applitools also has a plugin system to extend its functionality and can be integrated with other tools such as Jenkins for continuous integration and delivery.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/0sjhhox92hxiwh6nd7dh.png)_Source: Applitools_

4) _**Katalon**_ – another tool for automated testing of web-based applications. It is designed for both manual and automated testing and can be used with various programming languages, including Java, Python and JavaScript. Katalon comes with a suite of automated tests that allow you to quickly write and execute tests without having to write any code. In addition, Katalon has a rich feature set that allows you to customise your tests and integrate them with other tools.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/bbhlrzl3ljef9pzaa2la.png)_Source: BrowserStack_

5) _**Rainforest QA**_ – a no-code test automation platform, facilitating the process of maintaining end-to-end tests for web applications. Rainforest QA offers frontend testing services that include manual testing, automated testing, performance testing and user interface testing. They use a wide range of tools and techniques to ensure that your web applications are functional and meet user expectations.

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/dkgqpduwi3u7femo8dr4.png)_Source: Rainforest QA_

## Conclusion

_**In today’s world where technologies are developing at never-before-seen rates, frontend testing is becoming increasingly important.**_ _Without quality UI and UX testing, it is impossible to lead a project to success. Modern cutting-edge tools and practices allow you to automate testing, reduce testing time and increase its efficiency. However, it is important to realise that only quality testing can guarantee successful application performance and user satisfaction._