Invalidate node cache when using Jest

Question

I have a file with object that gets populated with process.env properties:

env.js

console.log('LOADING env.js');  const {   PROXY_PREFIX = '/api/',   USE_PROXY = 'true',   APP_PORT = '8080',   API_URL = 'https://api.address.com/',   NODE_ENV = 'production', } = process.env;  const ENV = {   PROXY_PREFIX,   USE_PROXY,   APP_PORT,   API_URL,   NODE_ENV, };  module.exports.ENV = ENV; 

Now I try to test this file with different process.env properties:

env.test.js

const envFilePath = '../../config/env';  describe('environmental variables', () => {   const OLD_ENV = process.env;    beforeEach(() => {     process.env = { ...OLD_ENV };     delete process.env.NODE_ENV;   });    afterEach(() => {     process.env = OLD_ENV;   });    test('have default values', () => {     const { ENV } = require(envFilePath);     expect(ENV).toMatchSnapshot();   });    test('are string values (to avoid casting errors)', () => {     const { ENV } = require(envFilePath);     Object.values(ENV).forEach(val => expect(typeof val).toEqual('string'));   });    test('will receive process.env variables', () => {     process.env.NODE_ENV = 'dev';     process.env.PROXY_PREFIX = '/new-prefix/';     process.env.API_URL = 'https://new-api.com/';     process.env.APP_PORT = '7080';     process.env.USE_PROXY = 'false';      const { ENV } = require(envFilePath);      expect(ENV.NODE_ENV).toEqual('dev');     expect(ENV.PROXY_PREFIX).toEqual('/new-prefix/');     expect(ENV.API_URL).toEqual('https://new-api.com/');     expect(ENV.APP_PORT).toEqual('7080');     expect(ENV.USE_PROXY).toEqual('false');   }); }); 

Unfortunately, even though I try to load the file in every test separately the file gets loaded only once, making the third test fail with:

Expected value to equal:   "dev" Received:   "production" 

P.S. It doesn't fail when I run the test alone.

I also know that env.js loads only once because console.log('LOADING env.js'); gets fired only once.

I tried to invalidate Nodes cache like:

  beforeEach(() => {     delete require.cache[require.resolve(envFilePath)];     process.env = { ...OLD_ENV };     delete process.env.NODE_ENV;   }); 

but require.cache is empty {} before each test so it seems that Jest is somehow responsible for importing the file.

I also tried to run yarn jest --no-cache but didn't help.

So what I want is to load env.js before each test so I can test how it behaves with different node environmental variables.

jest@^22.0.4

Answer 1

You can use jest.resetModules() in beforeEach method to reset the already required modules

beforeEach(() => {   jest.resetModules()   process.env = { ...OLD_ENV };   delete process.env.NODE_ENV; });