@jest/core
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Package description
The @jest/core package is the core engine of Jest, a popular JavaScript testing framework. It provides the functionality necessary to run tests, including the test runner, test watcher, and the ability to configure and initialize tests. It is designed for developers who need to write and run tests for their JavaScript code, offering a powerful and flexible testing environment.
Running tests
This feature allows you to programmatically run your tests using Jest. You can specify options and projects to run tests on, making it flexible for different testing scenarios.
jest.runCLI(options, projects).then(result => { console.log('Tests completed'); });Configuring Jest
This feature enables you to read and manipulate Jest's configuration programmatically. It's useful for custom setups or when integrating Jest into other tools.
const { readConfig } = require('@jest/core');
readConfig(argc, argv).then(config => { console.log('Jest config:', config); });Using the TestWatcher
The TestWatcher API allows you to listen to events related to the test lifecycle, such as when a test starts or finishes. This is useful for implementing custom behaviors or integrations.
const { TestWatcher } = require('@jest/core');
const watcher = new TestWatcher({ isWatchMode: true });
watcher.on('test_start', test => { console.log('Test started:', test.name); });Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple. It's similar to @jest/core in providing a testing framework, but differs in its interface and default behavior, such as having a different assertion library by default (Chai) and not including a mocking library.
Jasmine is a behavior-driven development framework for testing JavaScript code. It does not require a DOM, and it has a clean, obvious syntax so that you can easily write tests. Compared to @jest/core, Jasmine is more focused on the BDD aspect and comes with an assertion library out of the box, whereas Jest provides more utilities for mocking and spying.
AVA is a test runner for Node.js with a concise API, detailed error output, and process isolation for concurrent tests. It's designed to be fast and comes with built-in support for ES6. Unlike @jest/core, AVA emphasizes minimalism and parallel test execution, which can lead to faster test runs for certain projects.
Changelog
29.5.0
[jest-changed-files] Support Sapling (#13941)[jest-circus, @jest/cli, jest-config] Add feature to randomize order of tests via CLI flag or through the config file(#12922)[jest-cli, jest-config, @jest/core, jest-haste-map, @jest/reporters, jest-runner, jest-runtime, @jest/types] Add workerThreads configuration option to allow using worker threads for parallelization (#13939)[jest-cli] Export yargsOptions (#13970)[jest-config] Add openHandlesTimeout option to configure possible open handles warning. (#13875)[@jest/create-cache-key-function] Allow passing length argument to createCacheKey() function and set its default value to 16 on Windows (#13827)[jest-message-util] Add support for AggregateError (#13946 & #13947)[jest-message-util] Add support for Error causes in test and it (#13935 & #13966)[jest-reporters] Add summaryThreshold option to summary reporter to allow overriding the internal threshold that is used to print the summary of all failed tests when the number of test suites surpasses it (#13895)[jest-runtime] Expose @sinonjs/fake-timers async APIs functions advanceTimersByTimeAsync(msToRun) (tickAsync(msToRun)), advanceTimersToNextTimerAsync(steps) (nextAsync), runAllTimersAsync (runAllAsync), and runOnlyPendingTimersAsync (runToLastAsync) (#13981)[jest-runtime, @jest/transform] Allow V8 coverage provider to collect coverage from files which were not loaded explicitly (#13974)[jest-snapshot] Add support to cts and mts TypeScript files to inline snapshots (#13975)[jest-worker] Add start method to worker farms (#13937)[jest-worker] Support passing a URL as path to worker (#13982)[babel-plugin-jest-hoist] Fix unwanted hoisting of nested jest usages (#13952)[jest-circus] Send test case results for todo tests (#13915)[jest-circus] Update message printed on test timeout (#13830)[jest-circus] Avoid creating the word "testfalse" when takesDoneCallback is false in the message printed on test timeout AND updated timeouts test (#13954)[jest-environment-jsdom] Stop setting document to null on teardown (#13972)[@jest/expect-utils] Update toStrictEqual() to be able to check jest.fn().mock.calls (#13960)[@jest/test-result] Allow TestResultsProcessor type to return a Promise (#13950)[jest-snapshot] Remove dependency on jest-haste-map (#13977)Readme
Jest is currently working on providing a programmatic API. This is under development, and usage of this package directly is currently not supported.
FAQs
Delightful JavaScript Testing.
The npm package @jest/core receives a total of 18,133,862 weekly downloads. As such, @jest/core popularity was classified as popular.
We found that @jest/core demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 3 open source maintainers collaborating on the project.
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