Problem Statement
What is the Testing Pyramid concept?
Explanation
Testing Pyramid visualizes ideal test distribution: broad base of many fast unit tests, narrower middle layer of integration tests, narrow top of few end-to-end tests. Unit tests (70%) are fast, cheap, isolated testing individual functions/classes. Integration tests (20%) verify components work together, testing APIs, database interactions. E2E tests (10%) test entire application flow, slow and expensive but validate real user scenarios.
Rationale: unit tests provide fast feedback (milliseconds), catch most bugs early, easy to maintain. E2E tests are slow (seconds/minutes), brittle (break from UI changes), expensive to maintain. More unit tests ensure solid foundation, fewer E2E tests validate critical paths. Anti-pattern: inverted pyramid with mostly E2E tests results in slow, flaky test suites.
Pyramid implementation in CI/CD: run unit tests first (fail fast), run integration tests after unit tests pass, run E2E tests last or only on main branch. Fast feedback loop encourages frequent commits. Understanding testing pyramid ensures efficient, maintainable test strategy.
