Env variables not loaded for unit tests purpose

[lipoolock]

What version of Next.js are you using?

v10.0.9-canary.4

What version of Node.js are you using?

v14.16.0

What browser are you using?

Firefox

What operating system are you using?

Linux

How are you deploying your application?

no

Describe the Bug

If you set some environment variables in .env and .env.test they are not taken into account while playing unit tests and tests based on these variables fail

Expected Behavior

With NextJs 10.0.6 it works well

To Reproduce

You can login to sandbox and play the unit tests set here https://codesandbox.io/s/laughing-leaf-zfp7k?file=/__tests__/testing-library.js

If you run yarn test __tests__/testing-library.js you will get undefined instead of fooBar for the env variable set in .env.test

[ijjk]

Hi, Next.js isn't being invoked at all when running tests in the above set-up, you need to load the env manually with loadEnvConfig from @next/env. The above reproduction also fails on v10.0.6 since we never were loading environment variables at a per-page basis.

Closing as this doesn't appear to be a bug in Next.js and instead with the test set-up

[lipoolock]

Hello @ijjk
Thanks a lot for explanations
I just forgot that I previously used a workaround in jest.config proposed by @timneutkens there #1790
So I added it to the sandbox shared in this ticket.

But that requires to make the build of NextJs before launching tests
And this workaround doesn't work with the latest release by the way

But, by having a look again on that topic #1790 and thanks to your help, I have been able to make working my unit test

Below step to fix this issue

• Install @next/env
• In jest.config add this line globalSetup: '<rootDir>/test.env.js',
• in test.env.js add the block below

import { loadEnvConfig } from '@next/env'
import { resolve } from 'path'

export default async () => {
  const envFile = resolve(__dirname, '.')
  loadEnvConfig(envFile)
}

I would suggest to add this example in your doc, that could help all of us (as required by this (still opened) issue
#17903

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.