In the world of web development, ensuring the reliability and functionality of frontend code is crucial to ensuring a seamless user experience. Frontend testing plays an important role in achieving this goal. In this article, we’ll explore the ins and outs of frontend testing, including best practices, tools, and different types of testing. We’ll cover everything from unit testing and integration testing, to performance testing and end-to-end testing.

What is front end (FE)?

The front end is the part of the software application that is directly visible and interactive to the user. It represents a user interface that includes all the visual and interactive elements that users can see and interact with on the screen of their device, such as computers, phones and tablets.

How to understand frontend testing ?

Frontend testing involves evaluating the behavior, functionality, and performance of the user interface components of a web application. It’s a process that ensures your frontend code meets the required standards and delivers the expected results to your users. Frontend testing can be divided into several types.

Types of frontend testing

1. Unit testing

Unit testing focuses on isolated testing of individual components such as functions, classes or modules. This type of testing helps to identify bugs and flaws early in the development process. Unit testing frameworks such as Jest, Mocha and Jasmine are commonly used in frontend development. React developers often use tools like React Testing Library and Enzyme to facilitate unit testing in their applications.

Best practices for unit testing:

  • Write tests that cover different use cases for each component.
  • Use meaningful test names to increase readability.
  • Keep the tests independent and isolated from each other.

2. Integration Testing

Integration testing involves testing the interactions between the various components of the frontend to ensure that they work seamlessly. This type of testing helps to catch problems that may arise when components interact with each other. Tools such as Cypress and Selenium are commonly used for integration testing.

3. End-to-End (E2E) testing

End-to-end testing simulates real user scenarios by testing the entire user flow of an application. It ensures that all frontend and backend components work in harmony. E2E testing tools such as Cypress, Selenium and Puppeteer are widely used for this purpose.

4. Performance Testing

Performance testing evaluates how well your frontend application performs under various conditions, such as high user load or low network speed. Tools like Lighthouse and WebPageTest help you identify performance bottlenecks and optimize your application for better speed and responsiveness.

5. Manual testing

Frontend manual testing involves human testers interacting with the frontend application to identify visual bugs, usability issues, and other user-related problems. While manual testing is valuable, it is essential to add also automated testing to ensure consistent results.

Frontend testing best practices

  • Test early and often: start testing frontend code as early as possible in the development process. Frequent testing helps catch errors early, making it easier and cheaper to fix them.
  • Isolation: keep the tests isolated from each other. Each test should be independent and should not be dependent on the state of the previous tests.
  • Use realistic data: when writing tests, use realistic data and scenarios that users are likely to encounter. This will ensure that your tests accurately reflect real-world use.
  • Continuous Integration: integrate testing into the development workflow through continuous integration (CI). This will ensure that tests are automatically run whenever changes are made to the code.
2 hands point to the computer code on the monitor
Integrate testing into the development workflow to avoid bugs and errors in the code.

Automated testing for frontend – challenges

  • A constantly evolving user interface: in modern software, core libraries and third-party components need to be updated every few months. Updating one library requires appropriate changes to all other necessary components. All components, including automation and testing tools, need to be retested with each update.
  • Constantly changing user preferences: with new devices, browsers and operating system versions being introduced every few months, user requirements and preferences are constantly changing. For example, the pandemic has caused a rapid increase in user demand/requests for video conferencing and streaming. These newer user requirements need to be identified and implemented without significant delay.
  • Choosing the right automation tool: effective, regular testing of the front-end requires automation. Manual testers cannot be expected to run tests on every update. By choosing an automation tool that can be effectively set up and enhanced
  • Detecting problems across browsers and devices: with thousands of browser versions and devices used to access the internet around the world, testers have to cover a huge range to equip a site or app for real-world use. This can be challenging as new devices and browser versions are constantly being released. Using a cloud-based testing infrastructure is more affordable than, for example, BrowserStack.

Popular frontend testing tools

  • Jest: A widely used frontend testing framework for JavaScript testing that is suitable for both, unit testing and integration testing.
  • Cypress: It is an end-to-end testing framework that is known for its ease of use and real-time loading.
  • React: A component testing tool that emphasizes testing from the user’s perspective.
  • Selenium: A versatile testing framework that supports a variety of programming languages and browsers for both frontend and backend testing.
  • Lighthouse: a tool from Google that helps you assess the performance, accessibility and SEO of your web app.

How to create a website testing plan?

Step 1: Find tools to manage your test plan.

Step 2: Deciding on a budget for the tests.

Step 3: Establish a timeline for the entire process.

Step 4: Decision on the overall scope of the project. The scope includes the following items:

  • OS and browsers used by users,
  • popular devices used by users,
  • user competence.

Front end vs. Back end testing

While front-end testing focuses on the user interface and user experience, back-end testing evaluates server-side functionality and data processing. Both types of testing are essential to creating a robust and reliable web application. They complement each other and provide a complete quality assurance process.

Backend testing

Backend testing is an important part of software development that focuses on verifying the functionality and reliability of the server side of the application.

The back-end test is about examining various aspects of the server side of the application. This includes testing APIs, database connections, data manipulation, request processing, and proper communication with all components of the system. Here are a few important points to focus on during back-end testing:

  1. API Functionality: verifies that the API correctly receives requests and returns the expected responses. Different combinations of inputs and subsequent responses are tested.
  2. Correct data processing: the server is examined to ensure that it is handling the data correctly. This includes adding, updating and deleting data in the database.
  3. Database testing: it verifies that database queries work correctly and return the expected results. Different types of queries and their combinations are tested.
  4. Performance Testing: Examines how the application behaves under different load. Response time and speed of processing requests are measured.
  5. Security: server security is tested to minimize the possibility of attacks or misuse.


If you’re familiar with testing and looking for work, check out our job listings. We are currently looking for a Tosca tester. We have great employee benefits and a friendly company atmosphere.

About the author

Michaela Kojnoková

Agile Test Engineer

Po štúdiu informatiky na ŽU a TUKE som sa najviac ponorila do oblasti automatizácie testovania. Okrem toho sa venujem tvorbe webov, databázam, dátovej analytike, umelej inteligencii a strojovému učeniu. Mám rada cestovanie, šport a najviac si užívam čas strávený v prírode s mojimi blízkymi. LinkedIn

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