Example of test of a code without functions

runnable.spec.ts

import { stub } from 'sinon';
import { expect } from 'chai';

describe('runnable.ts', () => {
  let target = '../src/runnable.ts';

  beforeEach(() => {
    stub(console, 'log');
  });

  afterEach(() => {
    delete require.cache[require.resolve(target)];
    delete process.env.IS_GOODBYE;
  });

  it('should log hello world if IS_GOODBYE is not "true"', () => {
    process.env.IS_GOODBYE = 'anything else';

    require(target);

    expect(console.log).to.have.been.calledOnceWithExactly('hello world');
  });


  it('should log goodbye world if IS_GOODBYE is "true"', () => {
    process.env.IS_GOODBYE = 'true';

    require(target);

    expect(console.log).to.have.been.calledOnceWithExactly('goodbye world!');
  });
});