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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.


Version published
Weekly downloads
decreased by-12.38%

Weekly downloads





  • [jest-config] Do not warn about preset in ProjectConfig #13583


  • [jest-transform] Defer creation of cache directory #13420




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:


What is jest-validate?

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

Is jest-validate popular?

The npm package jest-validate receives a total of 15,687,456 weekly downloads. As such, jest-validate popularity was classified as popular.

Is jest-validate well maintained?

We found that jest-validate demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago.It has 6 open source maintainers collaborating on the project.

Last updated on 08 Nov 2022

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