CODEWITHSUNDEEP
nestts-jest
Pradip
Pradip

Reputation: 639

Forcing an environment variable value from a Jest file in TypeScript

I am trying to force some environment variables from the Jest testcase such that during execution, the code should take the proper path:

Basically my class-under-test looks like:

const myProvider =
      process.env.IS_LOCAL == 'true' ? localProvider : process.env.IS_MOCK == 'true' ? mockProvider : realProvider;

So basicaly I want to pickup the mockProvider by forcing the IS_MOCK as true.

These are the two things I have tried:

Adding a setup file setup.ts

process.env.IS_MOCK = 'true'
process.env.IS_LOCAL = 'false'

In the jest config:

  setupFiles: ['<rootDir>/setup.ts'],

Setting up the value from the test file:

  const env = process.env
  beforeAll(async () => {
    jest.resetModules()
    process.env = {
      ...env,
      IS_LOCAL: 'false', // 
      IS_MOCK: 'true', 
    };
  
   afterAll(async () => {
    process.env = env;
  });

None of these actually works here.

Any help would be good.

Upvotes: 0

Views: 801

Answers (1)

Pradip
Pradip

Reputation: 639

The only way it worked for me is to read the correct .env file in the test configuration itself.

This is my jest config file:

const dotEnv = require('dotenv');
dotEnv.config({ path: envFilePath_starting_from_where_jest_is_running });
console.log(`Running Jest with env: ${process.env.<your-env-variable>}`);

module.exports = {
 ....
}

Just install the dotenv as dev dependencies: npm install --save-def dotenv.

Then inside the Jest tests, one can check the env variable as:

const correctProvider: process.env.MOCK_ENV ? mockService : concreteService;
const moduleFixture: TestingModule = await Test.createTestingModule({
      imports: [AppModule]
    })
      .overrideProvider(Service)
      .useValue(correctProvider)
      .compile();

That's the best way I can do it.

Upvotes: 1

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