Cypress

This skill teaches you Cypress patterns that actually prevent flaky tests: data-testid selectors instead of brittle CSS, cy.intercept for network control, cy.session for fast auth, and deterministic waits instead of sleeps. It covers both E2E and component testing, with practical CI setup including retries and artifact management. The anti-patterns section is honest about what breaks in production (deep selectors, test order dependencies, mixing stubs with real backend calls). If you're debugging flaky UI tests or setting up browser automation for the first time, the troubleshooting guide alone is worth the tokens. Includes parallelization guidance for Cypress Cloud when test runtime becomes a bottleneck.