@jest/core
Advanced tools
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.
Jest is currently working on providing a programmatic API. This is under development, and usage of this package directly is currently not supported.
25.1.0
[babel-plugin-jest-hoist] Show codeframe on static hoisting issues (#8865)[babel-plugin-jest-hoist] Add BigInt to ALLOWED_IDENTIFIERS (#8382)[babel-preset-jest] Add @babel/plugin-syntax-bigint (#8382)[expect] Add BigInt support to toBeGreaterThan, toBeGreaterThanOrEqual, toBeLessThan and toBeLessThanOrEqual (#8382)[expect, jest-matcher-utils] Display change counts in annotation lines (#9035)[expect, jest-snapshot] Support custom inline snapshot matchers (#9278)[jest-config] Throw the full error message and stack when a Jest preset is missing a dependency (#8924)[jest-config] [BREAKING] Set default display name color based on runner (#8689)[jest-config] Merge preset globals with project globals (#9027)[jest-config] Support .cjs config files (#9291)[jest-config] [BREAKING] Support .mjs config files (#9431)[jest-core] Support reporters as default exports (#9161)[jest-core] Support --findRelatedTests paths case insensitivity on Windows (#8961)[jest-diff] Add options for colors and symbols (#8841)[jest-diff] [BREAKING] Export as ECMAScript module (#8873)[jest-diff] Add includeChangeCounts and rename Indicator options (#8881)[jest-diff] Add changeColor and patchColor options (#8911)[jest-diff] Add trailingSpaceFormatter option and replace cyan with commonColor (#8927)[jest-diff] Add firstOrLastEmptyLineReplacement option and export 3 diffLines functions (#8955)[jest-environment] Add optional getVmContext next to runScript (#9252 & #9428)[jest-environment-jsdom] Add fakeTimersLolex (#8925)[jest-environment-node] Add fakeTimersLolex (#8925)[jest-environment-node] Add queueMicrotask (#9140)[jest-environment-node] Implement getVmContext (#9252 & #9428)[@jest/fake-timers] Add Lolex as implementation of fake timers (#8897)[jest-get-type] Add BigInt support. (#8382)[jest-matcher-utils] Add BigInt support to ensureNumbers ensureActualIsNumber, ensureExpectedIsNumber (#8382)[jest-matcher-utils] Ignore highlighting matched asymmetricMatcher in diffs (#9257)[jest-reporters] Export utils for path formatting (#9162)[jest-reporters] Provides global coverage thresholds as watermarks for istanbul (#9416)[jest-runner] Warn if a worker had to be force exited (#8206)[jest-runtime] [BREAKING] Do not export ScriptTransformer - it can be imported from @jest/transform instead (#9256)[jest-runtime] Use JestEnvironment.getVmContext and vm.compileFunction if available to avoid the module wrapper (#9252 & #9428)[jest-snapshot] Display change counts in annotation lines (#8982)[jest-snapshot] [BREAKING] Improve report when the matcher has properties (#9104)[jest-snapshot] Improve colors when snapshots are updatable (#9132)[jest-snapshot] Ignore indentation for most serialized objects (#9203)[jest-transform] Create createTranspilingRequire function for easy transpiling modules (#9194)[jest-transform] [BREAKING] Return transformed code as a string, do not wrap in vm.Script (#9253)[@jest/test-result] Create method to create empty TestResult (#8867)[jest-worker] [BREAKING] Return a promise from end(), resolving with the information whether workers exited gracefully (#8206)[jest-reporters] Transform file paths into hyperlinks (#8980)[expect] Display expectedDiff more carefully in toBeCloseTo (#8389)[expect] Avoid incorrect difference for subset when toMatchObject fails (#9005)[expect] Consider all RegExp flags for equality (#9167)[expect] [BREAKING] Consider primitives different from wrappers instantiated with new (#9167)[expect] Prevent maintaining RegExp state between multiple tests (#9289)[expect] Fix subsetEquality false circular reference detection (#9322)[jest-config] Use half of the available cores when watchAll mode is enabled (#9117)[jest-config] Fix Jest multi project runner still cannot handle exactly one project (#8894)[jest-console] Add missing console.group calls to NullConsole (#9024)[jest-core] Don't include unref'd timers in --detectOpenHandles results (#8941)[jest-core] Limit number of workers when creating haste maps in projects (#9259)[jest-diff] Do not inverse format if line consists of one change (#8903)[jest-diff] Rename some new options and change their default values (#9077)[jest-environment-node] Fix TextEncoder.encode not referencing same global Uint8Array constructor (#9261)[jest-fake-timers] getTimerCount will not include cancelled immediates (#8764)[jest-fake-timers] Support util.promisify on setTimeout (#9180)[jest-jasmine2, jest-circus] Improve error message format for Node's assert.fail (#9262)[jest-leak-detector] [BREAKING] Use weak-napi instead of weak package (#8686)[jest-mock] Fix for mockReturnValue overriding mockImplementationOnce (#8398)[jest-reporters] Make node-notifier an optional dependency (#8918)[jest-reporters] Make all arguments to methods on BaseReporter optional (#9159)[jest-resolve]: Set MODULE_NOT_FOUND as error code when module is not resolved from paths (#8487)[jest-resolve-dependencies] Handle dynamic dependencies correctly even when using module maps (#9303)[jest-snapshot] Remove only the added newlines in multiline snapshots (#8859)[jest-snapshot] Distinguish empty string from external snapshot not written (#8880)[jest-snapshot] [BREAKING] Distinguish empty string from internal snapshot not written (#8898)[jest-snapshot] [BREAKING] Remove report method and throw matcher errors (#9049)[jest-snapshot] Omit irrelevant received properties when property matchers fail (#9198)[jest-transform] Properly cache transformed files across tests (#8890)[jest-transform] Don't fail the test suite when a generated source map is invalid (#9058)[jest-types] [BREAKING] Use less null | undefined in config types (#9200)[jest-util] Allow querying process.domain (#9136)[pretty-format] Correctly detect memoized elements (#9196)[pretty-format] Fix pretty-format to respect displayName on forwardRef (#9422)[*] [BREAKING] Drop support for Node 6 (#8455)[*] Add Node 12 to CI (#8411)[*] [BREAKING] Upgrade to Micromatch v4 (#8852)[babel-plugin-jest-hoist] [BREAKING] Use ESM exports (#8874)[docs] Add alias and optional boolean value to coverage CLI Reference (#8996)[docs] Fix broken link pointing to legacy JS file in "Snapshot Testing".[docs] Add setupFilesAfterEnv and jest.setTimeout example (#8971)[expect] Test that toStrictEqual is equivalent to Node's assert.deepStrictEqual (#9167)[jest] [BREAKING] Use ESM exports (#8874)[jest-cli] [BREAKING] Use ESM exports (#8874)[jest-cli] [BREAKING] Remove re-exports from @jest/core (#8874)[jest-diff] Remove the need to export splitLines0 function (#9151)[jest-environment-jsdom] [BREAKING] Upgrade JSDOM from v11 to v15 (#8851)[jest-haste-map] Upgrade to fsevents@2 (#9215)[jest-reporters] [BREAKING] Upgrade Istanbul dependencies, which are used for code coverage (#9192)[jest-util] [BREAKING] Remove deprecated exports (#8863)[jest-validate] [BREAKING] Use ESM exports (#8874)[jest-types] Mark InitialOptions as Partial (#8848)[jest-config] Refactor normalize to be more type safe (#8848)FAQs
Delightful JavaScript Testing.
The npm package @jest/core receives a total of 18,124,089 weekly downloads. As such, @jest/core popularity was classified as popular.
We found that @jest/core demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 3 open source maintainers collaborating on the project.
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