jest▌

Jest testing best practices for JavaScript and TypeScript projects with mocking, async handling, and React patterns. \n \n Organize tests with descriptive names in nested describe blocks, using .test.ts / .test.js files placed alongside source code or in __tests__ directories \n Mock external dependencies with jest.mock() , jest.spyOn() , and mockImplementation() , resetting between tests to prevent state leakage \n Handle async code with promises, async/await , and resolves / rejects matchers;

Comprehensive React component testing with Jest and React Testing Library covering configuration, mocking, async patterns, and best practices. \n \n Covers Jest configuration for JavaScript and TypeScript projects, including setup files, module mapping, and coverage thresholds \n Provides query strategies prioritizing accessibility (getByRole, getByLabelText) and explains getBy, queryBy, and findBy variants \n Includes mocking patterns for modules, functions, API calls via MSW, context, and chil

Jest is the industry-standard testing framework with 70% market share, providing a mature, battle-tested ecosystem for TypeScript projects. It offers comprehensive testing capabilities with built-in snapshot testing, mocking, and coverage reporting.