Mock process.env in Jest - full example

getAssetPath.test.ts

import getAssetPath from './getAssetPath';
describe('getAssetPath', () => {
  const originalEnv = process.env;
  
  describe.each`
    nodeEnv          | expectedPath
    ${'production'}  | ${'/production-path'}
    ${'development'} | ${'/development-path'}
    ${'test'}        | ${'/development-path'}
  `('when process.env.NODE_ENV="$nodeEnv"', ({ nodeEnv, expectedPath }) => {
    beforeEach(() => {
      jest.resetModules();
      process.env = {
        ...originalEnv,
        NODE_ENV: nodeEnv,
      };
    });
    
    afterEach(() => {
      process.env = originalEnv;
    });
    
    it(`should return "${expectedPath}"`, () => {
      expect(getAssetPath()).toEqual(expectedPath);
    });
  });
});