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Generic configuration validation tool that helps you with warnings, errors and deprecation messages as well as showing users examples of correct configuration.


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  • [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)

Chore & Maintenance

  • [jest-snapshot] Remove dependency on jest-haste-map (#13977)




Generic configuration validation tool that helps you with warnings, errors and deprecation messages as well as showing users examples of correct configuration.

npm install --save jest-validate


import {validate} from 'jest-validate'; validate(config, validationOptions); // => {hasDeprecationWarnings: boolean, isValid: boolean}

Where ValidationOptions are:

type ValidationOptions = { comment?: string; condition?: (option: unknown, validOption: unknown) => boolean; deprecate?: ( config: Record<string, unknown>, option: string, deprecatedOptions: DeprecatedOptions, options: ValidationOptions, ) => boolean; deprecatedConfig?: DeprecatedOptions; error?: ( option: string, received: unknown, defaultValue: unknown, options: ValidationOptions, path?: Array<string>, ) => void; exampleConfig: Record<string, unknown>; recursive?: boolean; recursiveBlacklist?: Array<string>; recursiveDenylist?: Array<string>; title?: Title; unknown?: ( config: Record<string, unknown>, exampleConfig: Record<string, unknown>, option: string, options: ValidationOptions, path?: Array<string>, ) => void; }; type Title = { deprecation?: string; error?: string; warning?: string; };

exampleConfig is the only option required.


By default jest-validate will print generic warning and error messages. You can however customize this behavior by providing options: ValidationOptions object as a second argument:

Almost anything can be overwritten to suite your needs.


  • recursiveDenylist – optional array of string keyPaths that should be excluded from deep (recursive) validation.
  • comment – optional string to be rendered below error/warning message.
  • condition – an optional function with validation condition.
  • deprecate, error, unknown – optional functions responsible for displaying warning and error messages.
  • deprecatedConfig – optional object with deprecated config keys.
  • exampleConfig – the only required option with configuration against which you'd like to test.
  • recursive - optional boolean determining whether recursively compare exampleConfig to config (default: true).
  • title – optional object of titles for errors and messages.

You will find examples of condition, deprecate, error, unknown, and deprecatedConfig inside source of this repository, named respectively.

exampleConfig syntax

exampleConfig should be an object with key/value pairs that contain an example of a valid value for each key. A configuration value is considered valid when:

  • it matches the JavaScript type of the example value, e.g. string, number, array, boolean, function, or object
  • it is null or undefined
  • it matches the Javascript type of any of arguments passed to MultipleValidOptions(...)

The last condition is a special syntax that allows validating where more than one type is permissible; see example below. It's acceptable to have multiple values of the same type in the example, so you can also use this syntax to provide more than one example. When a validation failure occurs, the error message will show all other values in the array as examples.


Minimal example:

validate(config, {exampleConfig});

Example with slight modifications:

validate(config, { comment: ' Documentation:', deprecatedConfig, exampleConfig, title: { deprecation: 'Custom Deprecation', // leaving 'error' and 'warning' as default }, });

This will output:

● Validation Warning: Unknown option transformx with value "<rootDir>/node_modules/babel-jest" was found. This is either a typing error or a user mistake. Fixing it will remove this message. Documentation:
● Validation Error: Option transform must be of type: object but instead received: string Example: { "transform": { "\\.js$": "<rootDir>/preprocessor.js" } } Documentation:

Example validating multiple types

import {multipleValidOptions} from 'jest-validate'; validate(config, { // `bar` will accept either a string or a number bar: multipleValidOptions('string is ok', 2), });
● Validation Error: Option foo must be of type: string or number but instead received: array Example: { "bar": "string is ok" } or { "bar": 2 } Documentation:

Based on deprecatedConfig object with proper deprecation messages. Note custom title:

Custom Deprecation: Option scriptPreprocessor was replaced by transform, which support multiple preprocessors. Jest now treats your current configuration as: { "transform": {".*": "xxx"} } Please update your configuration. Documentation:


Last updated on 06 Mar 2023

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