testing

End-to-end testing verifies complete user flows through a real browser, comparing Cypress and Playwright on architecture, cross-browser support, debugging, and performance to choose the right tool for your project.

Test-Driven Development (Red-Green-Refactor cycle) versus Behavior-Driven Development (Given-When-Then specifications), when each methodology shines, and how to apply them in practice for JavaScript projects.

How to test application performance with benchmarks, Web Vitals monitoring, Lighthouse CI integration, and performance budgets that prevent regressions in bundle size and runtime metrics.

Designing a comprehensive testing strategy using the testing trophy, defining what to test at each level, setting coverage targets, integrating tests into CI/CD, and making pragmatic trade-offs for large-scale applications.

Catching unintended UI changes with visual regression testing using screenshot comparison tools like Percy, Chromatic, and Playwright, including how pixel diffing works and when visual tests add value.