jest-validate

What is jest-validate?

The jest-validate package is a utility for validating and ensuring that configurations passed to Jest, the JavaScript testing framework, are correct. It checks if the provided configuration object adheres to Jest's expected configurations and provides warnings or errors for any invalid or unknown options. This helps developers to quickly identify issues with their Jest setup.

What are jest-validate's main functionalities?

Validation of configuration objects

This feature allows developers to validate their Jest configuration objects against a schema. It ensures that the configuration provided matches the expected format and values that Jest can work with.

{"validateConfig": require('jest-validate').validateConfig, "config": { "verbose": true }, "exampleConfig": { "verbose": false }}

Customization of validation messages

Developers can provide custom messages for unknown or deprecated options. This helps in guiding the user to correct their configuration with helpful feedback.

{"validateConfig": require('jest-validate').validateConfig, "config": { "unknownOption": true }, "exampleConfig": { "verbose": false }, "options": { "comment": "A custom message for unknownOption" }}

Deprecation warnings

jest-validate can warn users about deprecated configuration options. It provides a mechanism to inform users about the new options they should use instead.

{"validateConfig": require('jest-validate').validateConfig, "config": { "scriptPreprocessor": "<rootDir>/preprocessor.js" }, "exampleConfig": { "transform": {"^.+\\.js$": "<rootDir>/preprocessor.js"} }, "deprecatedConfig": { "scriptPreprocessor": "Please use `transform` instead" }}

Other packages similar to jest-validate

convict

Convict is a configuration management library for Node.js that includes schema validation. It is similar to jest-validate in that it validates configuration objects, but it is more general-purpose and not tied to a specific framework like Jest.

joi

Joi is a powerful schema description language and data validator for JavaScript. Unlike jest-validate, which is tailored for Jest configurations, Joi can be used for validating any kind of data structures and is often used for validating API input.

yup

Yup is a JavaScript schema builder for value parsing and validation. Similar to Joi, it defines a schema to validate objects against. It is less verbose and more expressive in some cases compared to Joi and is not specific to Jest configurations.

README

jest-validate

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

Usage

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.

API

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.

Options

• 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.

Examples

Minimal example:

validate(config, {exampleConfig});

Example with slight modifications:

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

This will output:

Warning:

● 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: http://custom-docs.com

Error:

● Validation Error:

  Option transform must be of type:
    object
  but instead received:
    string

  Example:
  {
    "transform": {
      "\\.js$": "<rootDir>/preprocessor.js"
    }
  }

  Documentation: http://custom-docs.com

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),
});

Error:

● Validation Error:

  Option foo must be of type:
    string or number
  but instead received:
    array

  Example:
  {
    "bar": "string is ok"
  }

  or

  {
    "bar": 2
  }

  Documentation: http://custom-docs.com

Deprecation

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: http://custom-docs.com

Example validating CLI arguments

import {validate} from 'jest-validate';

validateCLIOptions(argv, {...allowedOptions, deprecatedOptions});

If argv contains a deprecated option that is not specified in allowedOptions, validateCLIOptions will throw an error with the message specified in the deprecatedOptions config:

● collectCoverageOnlyFrom:

  Option "collectCoverageOnlyFrom" was replaced by "collectCoverageFrom"

  CLI Options Documentation: https://jestjs.io/docs/en/cli.html

If the deprecation option is still listed in the allowedOptions config, then validateCLIOptions will print the warning without throwing an error.