jest-cli

What is jest-cli?

The jest-cli npm package is the command line interface for Jest, a popular JavaScript testing framework. It allows developers to run tests, configure Jest options, and interact with Jest directly from the command line. Jest is widely used for testing React applications, but it can also be used for testing other JavaScript code.

What are jest-cli's main functionalities?

Running Tests

Run all tests in a project. This is the most basic and commonly used command to start the Jest test runner.

jest

Running Tests in Watch Mode

Run Jest in watch mode. This command will re-run tests when files change, which is useful during development.

jest --watch

Running Specific Tests

Run tests in a specific file or files matching a pattern. This allows for more targeted testing.

jest testFileName

Configuring Jest

Specify a configuration file for Jest. This allows developers to customize how Jest behaves, including setting up test environments, mock implementations, and more.

jest --config=jest.config.js

Coverage Reporting

Generate a test coverage report. This helps developers understand which parts of their codebase are covered by tests.

jest --coverage

Other packages similar to jest-cli

mocha

Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple. It's often compared to Jest but is considered more flexible and less opinionated, though it requires more setup and configuration.

jasmine

Jasmine is a behavior-driven development framework for testing JavaScript code. It does not require a DOM and has no dependencies, making it suited for websites, Node.js projects, or anywhere JavaScript can run. It's similar to Jest but has a different syntax and set of features.

ava

AVA is a test runner for Node.js with a concise API, detailed error output, and process isolation that lets you develop with confidence. It's different from Jest in that it runs tests concurrently, which can be faster, but it may not be as feature-rich as Jest.

tape

Tape is a tap-producing test harness for Node.js and browsers. It's minimalistic and straightforward, with less abstraction than Jest. It's suitable for small to medium-sized projects that don't need the extensive features Jest provides.

README

Jest

Painless JavaScript Unit Testing

• Familiar Approach: Built on top of the Jasmine test framework, using familiar expect(value).toBe(other) assertions

• Mock by Default: Automatically mocks CommonJS modules returned by require(), making most existing code testable

• Short Feedback Loop: DOM APIs are mocked and tests run in parallel via a small node.js command line utility

Getting Started

Check out the Getting Started tutorial. It's pretty simple!

API

<generated_api_start />

The jest object

• jest.autoMockOff()
• jest.autoMockOn()
• jest.clearAllTimers()
• jest.dontMock(module)
• jest.genMockFromModule(moduleObj)
• jest.genMockFunction()
• jest.genMockFn()
• jest.mock(moduleName)
• jest.runAllTicks()
• jest.runAllTimers()
• jest.runOnlyPendingTimers()
• jest.setMock(moduleName, moduleExports)

Mock functions

• mockFn.mock.calls
• mockFn.mock.instances
• mockFn.mockClear()
• mockFn.mockImplementation(fn)
• mockFn.mockImpl(fn)
• mockFn.mockReturnThis()
• mockFn.mockReturnValue(value)
• mockFn.mockReturnValueOnce(value)

Config options

• config.collectCoverage [boolean]
• config.collectCoverageOnlyFrom [object]
• config.modulePathIgnorePatterns [array]
• config.rootDir [string]
• config.scriptPreprocessor [string]
• config.setupEnvScriptFile [string]
• config.setupTestFrameworkScriptFile [string]
• [config.testDirectoryName string
• config.testFileExtensions [array]
• config.testPathDirs [array]
• config.testPathIgnorePatterns [array]
• config.unmockedModulePathPatterns [array]

Globally injected variables

• afterEach(fn)
• beforeEach(fn)
• describe(name, fn)
• it(name, fn)
• it.only(name, fn) executes only this test. Useful when investigating a failure
• jest
• pit(name, fn) helper for promises
• require(module)
• require.requireActual(module)
• xdescribe(name, fn)
• xit(name, fn)

expect(value)

• .not inverse the next comparison
• .toThrow(?message)
• .toBe(value) comparison using ===
• .toEqual(value) deep comparison. Use jasmine.any(type) to be softer
• .toBeFalsy()
• .toBeTruthy()
• .toBeNull()
• .toBeUndefined()
• .toBeDefined()
• .toMatch(regexp)
• .toContain(string)
• .toBeCloseTo(number, delta)
• .toBeGreaterThan(number)
• .toBeLessThan(number)
• .toBeCalled()
• .toBeCalledWith(arg, um, ents)
• .lastCalledWith(arg, um, ents)

<generated_api_end />