Test process.env with Jest
Jest's setupFiles
is the proper way to handle this, and you need not install dotenv
, nor use an .env
file at all, to make it work.
jest.config.js
:
module.exports = {
setupFiles: ["<rootDir>/.jest/setEnvVars.js"]
};
.jest/setEnvVars.js
:
process.env.MY_CUSTOM_TEST_ENV_VAR = 'foo'
That's it.
Another option is to add it to the jest.config.js
file after the module.exports
definition:
process.env = Object.assign(process.env, {
VAR_NAME: 'varValue',
VAR_NAME_2: 'varValue2'
});
This way it's not necessary to define the environment variables in each .spec
file and they can be adjusted globally.
In ./package.json
:
"jest": {
"setupFiles": [
"<rootDir>/jest/setEnvVars.js"
]
}
In ./jest/setEnvVars.js
:
process.env.SOME_VAR = 'value';
The way I did it can be found in this Stack Overflow question.
It is important to use resetModules before each test and then dynamically import the module inside the test:
describe('environmental variables', () => {
const OLD_ENV = process.env;
beforeEach(() => {
jest.resetModules() // Most important - it clears the cache
process.env = { ...OLD_ENV }; // Make a copy
});
afterAll(() => {
process.env = OLD_ENV; // Restore old environment
});
test('will receive process.env variables', () => {
// Set the 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 testedModule = require('../../config/env').default
// ... actual testing
});
});
If you look for a way to load environment values before running the Jest look for the answer below. You should use setupFiles for that.