Testing is the practice of verifying that software behaves correctly and keeps working as it changes, catching bugs before users do. A balanced strategy follows the testing pyramid: many fast unit tests for individual functions and components, a smaller set of integration tests for APIs, databases, and service interactions, and a few end-to-end tests that simulate real user flows. Common tools include Jest, Vitest, or Pytest for unit tests, Postman or Supertest for API testing, and Cypress or Playwright for browser automation, with XCTest and Espresso covering native iOS and Android apps. Tests run automatically in CI pipelines such as GitHub Actions on every commit, so regressions surface early. Teams also use mocks and fixtures to isolate dependencies, track code coverage as a guide rather than a goal, and add performance, security, and accessibility checks where they matter. For AI-powered features, evaluation sets and output validation help keep responses consistent.

If you share which testing tools you actually used (for example Jest, Pytest, or Playwright), I can tailor this to your project.