jest
JavaScript testing framework with focus on simplicity
TLDR
Run all tests
$ jest
Run specific test file$ jest [path/to/test.js]
Run tests matching pattern$ jest -t "[pattern]"
Run in watch mode$ jest --watch
Generate coverage report$ jest --coverage
Update snapshots$ jest -u
Run tests in parallel$ jest --maxWorkers=[4]
Run only changed tests$ jest --onlyChanged
SYNOPSIS
jest [options] [files...]
DESCRIPTION
jest is a JavaScript testing framework with focus on simplicity. It provides test runners, assertions, mocking, and code coverage in a single package.The tool features snapshot testing, parallel execution, and intelligent test selection. It works with React, Vue, Node.js, and most JavaScript projects.
PARAMETERS
--watch
Watch mode for changed files.--watchAll
Watch all files.--coverage
Collect code coverage.-t pattern
Run matching test names.-u, --updateSnapshot
Update snapshots.--maxWorkers n
Max parallel workers.--onlyChanged
Run only changed tests.--bail
Stop on first failure.--verbose
Display individual test results.--config file
Configuration file.--ci
CI mode settings.
CAVEATS
Default test regex may miss files. Snapshots need review. Coverage may miss edge cases. Memory usage high with many tests.
HISTORY
Jest was created by Facebook (Meta), initially for testing React applications. Released around 2014, it evolved from Jasmine roots to become one of the most popular JavaScript testing frameworks, known for its zero-configuration approach.
SEE ALSO
npm(1), mocha(1), vitest(1), playwright(1)
