README.md

jest-create-cache-key-function

This module creates a function which is used for generating cache keys used by code transformers in Jest.

Install

$ npm install --save-dev @jest/create-cache-key-function

API

createCacheKey(files?: Array<string>, values?: Array<String>, length?: number): GetCacheKeyFunction

Provides a function that computes the cache key given a collection of files and values. This limits the output with a provided length.

Parameters

• files: [Optional] Array of absolute paths to files whose code should be accounted for when generating cache key
• values: [Optional] Array of string values that should be accounted for when generating cache key
• length: [Optional] length of the resulting key defaults to 16 on win32 and 32 elsewhere

Note:

The source code for your test is already taken into account when generating the cache key. The files array should be used to provide files that are not directly related to your code such as external configuration files.

Usage

Here is some sample usage code while creating a new transformer for Jest

const createCacheKeyFunction =
  require('@jest/create-cache-key-function').default;

const filesToAccountFor = [
  __filename,
  require.resolve('some-package-name/package.json'),
];

const valuesToAccountFor = [process.env.SOME_LOCAL_ENV, 'Some_Other_Value'];

module.exports = {
  process(src, filename, config, options) {},
  getCacheKey: createCacheKeyFunction(filesToAccountFor, valuesToAccountFor),
};