Testing
advancedTopic 12 of 14 in Frontend Development
What it is
Testing is writing code that checks whether your app works correctly. Frontend testing includes unit tests (individual functions), component tests (UI pieces), and end-to-end tests (full user flows).
Why frontend developers need it
Tests catch bugs before users do. They let you refactor with confidence, onboard new teammates safely, and ship faster. Most professional teams require tests before merging code.
What to learn
Unit testing with Vitest or Jest
Component testing with React Testing Library
Mocking API calls and modules
End-to-end testing with Playwright or Cypress
Test-driven development (TDD) workflow
Code coverage and what it actually measures
Practice project
Tested Task Manager
Take your task manager app and add a full test suite: unit tests for utility functions, component tests for the task list and form, and one end-to-end test for the complete add-complete-delete flow.