Frontend Testing: Quality and Confidence in Code

For a long time I thought that writing tests was a waste of time. I preferred to code new features instead of checking that the old ones still worked. But then, every time I refactored code or added a new feature, something would break. And when would I discover it? Often, too late. That made me understand the importance of frontend testing.

Today, tests are an essential part of my workflow. They help me prevent errors, refactor with confidence, and maintain code quality in the long term.

Why do we test in frontend?

Frontend code is complex: user interactions, dynamic state, API calls, conditional rendering… All of this can fail in unexpected ways. Automated tests allow me to validate that everything works as expected, without having to do repetitive manual testing every time I change something.

My main tools

• Vitest / Jest: For unit and integration tests. I validate functions, React hooks, individual components, and their logic.
• Cypress / Playwright: For end-to-end (E2E) tests. I simulate the behavior of a real user navigating the application.
• Testing Library: To test components in a way that reflects how users actually interact with them.

My approach

I try to follow the principle of pragmatic testing: I don’t test everything, I test what has the highest risk of failing or what’s critical to the business. This includes complex logic, authentication flows, forms, and API integrations.

Tests not only improve code quality, they also improve my confidence when deploying to production. And when working in a team, they’re fundamental to prevent a teammate’s change from breaking my code.