jest-matcher-utils
Advanced tools
The jest-matcher-utils package provides utility functions for creating custom Jest matchers. It is designed to help developers write their own matchers that integrate seamlessly with Jest's built-in expectation system, offering a way to extend Jest's assertion capabilities with custom logic. The utilities provided by this package include formatting values for error messages, comparing values, and generating matcher error messages.
pretty-format
Formats any JavaScript value for pretty printing, which is useful for generating readable error messages in custom matchers.
const { prettyFormat } = require('jest-matcher-utils');
console.log(prettyFormat({ foo: 'bar' }));matcherHint
Generates a hint string for a matcher, which can be used at the beginning of error messages to indicate which matcher failed.
const { matcherHint } = require('jest-matcher-utils');
console.log(matcherHint('.toBe'));printExpected and printReceived
These functions format the expected and received values to be included in error messages, applying color highlighting to improve readability.
const { printExpected, printReceived } = require('jest-matcher-utils');
console.log(`Expected: ${printExpected(true)}
Received: ${printReceived(false)}`);Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework. It offers similar functionality to jest-matcher-utils in the sense that it provides a rich set of assertions and plugins to extend its capabilities. However, Chai is a standalone assertion library, not tied to any specific test runner like Jest.
Expect is a minimalist assertion library that comes with Jest but can also be used independently. It provides a similar API for writing test assertions as jest-matcher-utils, but jest-matcher-utils focuses more on the utilities for creating custom matchers rather than providing a comprehensive set of built-in matchers.
25.2.0
[jest-config] Support ESM config files with .js extension (#9573).[jest-runtime] Override module.createRequire to return a Jest-compatible require function (#9469)[jest-haste-map] [BREAKING] Remove mapper option (#9581)[*] Support array of paths for moduleNameMapper aliases (#9465)[jest-reporters] Adds ability to pass options to the istanbul-reporter through coverageReporters (#9572)[jest-runtime] Require stack when a module cannot be resolved (#9681)[jest-transform] writeCacheFile no longer calls fsync (#9695)[expect] Handle readonly properties correctly (#9575)[jest-cli] Set coverageProvider correctly when provided in config (#9562)[jest-cli] Allow specifying .cjs and .mjs config files by --config CLI option (#9578)[jest-cli] Update yargs to fix CLI flag overriding (#9519)[jest-config] Treat setupFilesAfterEnv like setupFiles when normalizing configs against presets (#9495)[jest-config] Support .mjs config files on Windows as well (#9558)[jest-config] Verify rootDir and all roots are directories (#9569)[jest-config] Ensure pattern of replacePosixSep is a string (#9546)[jest-haste-map] Fix crash on unix based systems without find (#9579)[jest-jasmine2] Fix --testNamePattern matching with concurrent tests (#9090)[jest-matcher-utils] Fix diff highlight of symbol-keyed object. (#9499)[@jest/reporters] Notifications should be fire&forget rather than having a timeout (#9567)[jest-resolve] Fix module identity preservation with symlinks and browser field resolution (#9511)[jest-resolve] Do not confuse directories with files (#8912)[jest-resolve] moduleNameMapper should take precedence over Node core modules (#9563)[jest-runtime] Reset isolateModules if it fails (#9541)[jest-runtime] Yarn PnP errors displayed to the user (#9681)[jest-snapshot] Downgrade semver to v6 to support node 8 (#9451)[jest-snapshot] Properly indent new snapshots in the presences of existing ones (#9523)[jest-transform] Correct sourcemap behavior for transformed and instrumented code (#9460)[jest-transform] Allow instrumentation of transformed files with weird file extensions (#9589)[@jest/types] Make ConfigGlobals an interface to allow for declaration merging. (#9570)[pretty-format] Export OldPlugin type (#9491)[docs] Warn about unexpected behavior / bug of node-notifier when using the notify options.[docs] Grammatical corrections to Async docs page. (#9679)[jest-resolver] Use resolve package to implement custom module resolution (#9520)[jest-runtime] Move execution of setupFiles to jest-runner (#9596)[jest-runtime] Update anchor link in helpers (#9616)[@jest/reporters] Remove unused dependencies and type exports (#9462)[website] Update pictures of reports when matchers fail (#9214)[jest-haste-map] Reduce number of lstat calls in node crawler (#9514)FAQs
A set of utility functions for expect and related packages
The npm package jest-matcher-utils receives a total of 26,454,742 weekly downloads. As such, jest-matcher-utils popularity was classified as popular.
We found that jest-matcher-utils demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 6 open source maintainers collaborating on the project.
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