30 articles
RSSHow to fix Node.js built-in test runner errors — node --test not finding files, ESM vs CJS imports, TypeScript with --experimental-strip-types, mock.method isolation, coverage reporting, and watch mode setup.
How to fix Playwright component testing errors — playwright-ct.config not found, mount fixture undefined, CSS not loaded in tests, Vite alias for imports, TypeScript paths, hooks (beforeMount), and snapshot strategy.
How to fix Bun test runner issues — mock.module not isolating, happy-dom setup for DOM tests, --coverage missing files, timer mocks, snapshot updates, TypeScript path aliases, and preload files.
How to fix freezegun errors — freeze_time decorator not affecting datetime.now, timezone-aware datetime mismatch, time.time not frozen, async test time leak, third-party library still using real time, and tick parameter behavior.
How to fix Moto errors — mock not activating, real AWS credentials used in tests, ImportError mock_s3 removed in v5, fixtures with multiple services, NoCredentialsError despite mock, and standalone server mode.
How to fix Nox errors — no noxfile.py found, session not detected, virtualenv backend uv not installed, session.install fails outside virtualenv, parametrize matrix exploding, and reuse_venv confusion.
How to fix Hypothesis errors — Unsatisfied assumption, Flaky test detected, HealthCheck data_too_large, strategy composition failing, example database stale, settings profile not found, and stateful testing errors.
How to fix Locust errors — no locustfile found, User class not detected, worker connection refused, distributed mode throughput lower than single-node, StopUser exception, FastHttpUser vs HttpUser, and headless CSV reports.
How to fix Selenium errors — WebDriverException session not created, NoSuchElementException element not found, StaleElementReferenceException, TimeoutException waiting for element, headless Chrome crashes, and driver version mismatch.
How to fix Tox errors — ERROR cannot find Python interpreter, tox.ini config parsing error, allowlist_externals required, recreating environments slow, pyproject.toml integration, and matrix env selection.
How to fix Supertest HTTP testing issues — Express and Fastify setup, async test patterns, authentication headers, file uploads, JSON body assertions, and Vitest/Jest integration.
How to fix Cypress issues — element selection strategies, async command chaining, cy.intercept for network stubbing, component testing, authentication handling, and flaky test debugging.
How to fix Mock Service Worker issues — browser vs Node setup, handler registration, worker start timing, passthrough requests, and common MSW v2 API changes from v1.
How to fix Playwright test issues — locator strategies, auto-waiting, network mocking, flaky tests in CI, trace viewer debugging, and common headless browser setup problems.
How to fix Storybook issues — CSF3 story format, addon configuration, webpack vs Vite builder, decorator setup, args not updating component, and Storybook 8 migration problems.
How to fix Go testing issues — test function naming, table-driven tests, t.Run subtests, httptest, testify assertions, and common go test flag errors.
How to fix Jest setup file issues — setupFilesAfterFramework vs setupFiles, global mocks not applying, @testing-library/jest-dom matchers, module mocking in setup, and TypeScript setup files.
How to fix Spring Boot test issues — @SpringBootTest vs test slices, MockMvc setup, @MockBean vs @Mock, test context caching, and common test configuration mistakes.
How to fix React Testing Library query failures — getByRole vs getByText, async queries, accessible names, waitFor patterns, custom queries, and common selector mistakes.
How to fix Jest async test timeouts — missing await, unresolved Promises, done callback misuse, global timeout configuration, fake timers, and async setup/teardown issues.
How to fix Jest coverage not collecting all files — collectCoverageFrom config, coverage thresholds, Istanbul ignore comments, ts-jest setup, and Babel transform issues.
How to fix Jest fake timers not working — useFakeTimers setup, runAllTimers vs advanceTimersByTime, async timers, React testing with act(), and common timer test mistakes.
How to fix Jest module mocks not working — hoisting behavior, ES module mocks, factory functions, mockReturnValue vs implementation, and clearing mocks between tests.
How to fix Jest failing with 'Cannot use import statement outside a module' — configuring Babel transforms, using experimental VM modules, migrating to Vitest, and handling ESM-only packages.
How to fix Jest snapshot failures — updating outdated snapshots, removing obsolete ones, fixing inline snapshots, preventing brittle snapshot tests, and managing snapshots in CI.
How to fix Vitest configuration not taking effect — why setupFiles don't run, globals are undefined, mocks don't work, and how to configure Vitest correctly for React, Vue, and Node.js projects.
How to fix jest.mock() not intercepting module calls — why mocks are ignored, how to correctly mock ES modules, default exports, named exports, and fix hoisting issues in Jest tests.
How to fix Jest 'Exceeded timeout of 5000ms for a test' errors caused by unresolved promises, missing done callbacks, async/await mistakes, and slow database or network calls in tests.
How to fix the Jest 'Cannot find module' error by configuring moduleNameMapper, moduleDirectories, tsconfig paths, and resolving ESM, monorepo, and dependency issues.
How to fix pytest errors like 'fixture not found', 'ERRORS collecting test', or 'no tests ran' caused by missing conftest.py, wrong scope, or import issues.