CODEWITHSUNDEEP
javascriptnode.jstypescriptunit-testingjestjs
Sandro Rey
Sandro Rey

Reputation: 2999

set env variable when Running jest

I have this variable defined on my main.ts

const mockMode = process.env.MOCK_MODE;

I just create a test and set this variable to true, but on the main does not get 'true', but 'false'

describe('onBook', () => {

    // Arrange
     const mockMode = "true";
     ...

Upvotes: 5

Views: 19857

Answers (1)

Lin Du
Lin Du

Reputation: 102587

You can set the value of process.env.MOCK_MODE directly within the unit test case and restore it to original value at the end.

E.g.

main.ts:

export function main() {
  const mockMode = process.env.MOCK_MODE;
  return mockMode;
}

main.test.ts:

import { main } from './main';

describe('main', () => {
  it('should pass', () => {
    const original = process.env.MOCK_MODE;
    process.env.MOCK_MODE = 'true';
    const actual = main();
    expect(actual).toBe('true');
    process.env.MOCK_MODE = original;
  });
  it('should restore MOCK_MODE', () => {
    expect(process.env.MOCK_MODE).toBe('undefined');
  });
});

Unit test result:

 PASS  src/stackoverflow/59319610/main.test.ts (14.207s)
  main
    ✓ should pass (7ms)
    ✓ should restore MOCK_MODE (1ms)

Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        16.293s

Upvotes: 6

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