testland/jest-tests
Configures and runs Jest - Meta-built batteries-included JS/TS unit framework with built-in `expect`, snapshot testing, mocking (`jest.mock`, `jest.fn`, `jest.spyOn`, manual `__mocks__/`), test environment selection (`jsdom` / `node`), parallel workers, coverage via Istanbul, watch mode, and CI integration via `--ci` flag. Use when the user works with React (CRA / older Next.js) or Node services and needs the most ecosystem-supported JS test framework.
75
94%
Does it follow best practices?
Run evals on this skill
Adds up to 20 points to the overall score
View guide
Passed
No findings from the security scan
configuration.mdreferences/
Jest configuration
Deep reference for jest-tests SKILL.md. Consult when generating or tuning
jest.config.js - test environment, coverage collection, path aliases.
Generate config (per jest-start):
npm init jest@latestCommon jest.config.js settings:
module.exports = {
testEnvironment: 'jsdom', // 'jsdom' for browser; 'node' for backend
setupFilesAfterEach: ['<rootDir>/jest.setup.js'],
testMatch: ['**/__tests__/**/*.[jt]s?(x)', '**/?(*.)+(spec|test).[jt]s?(x)'],
transform: {
'^.+\\.(ts|tsx)$': 'ts-jest',
},
collectCoverageFrom: ['src/**/*.{js,ts}', '!src/**/*.d.ts'],
coverageThreshold: {
global: {
branches: 80,
functions: 80,
lines: 80,
statements: 80,
},
},
moduleNameMapper: {
'^@/(.*)$': '<rootDir>/src/$1', // path aliases matching tsconfig
},
};testEnvironment defaults to jsdom in Jest 26 and earlier; from Jest 27+
defaults to node. Set explicitly to avoid surprise.