How to mock readline.createInterface()?

I'm trying to write a test on jasmine to check that readline.createInterface() is called, but I keep getting an error that says: TypeError: readline.createInterface is not a function

Here's roughly what I have in a game class:

run() {
  let rl = readline.createInterface({
      input: process.stdin,
      output: process.stdout,
      prompt: 'OHAI> '
    });

  rl.prompt();
  // ... and the rest ... 
}

and my test:

describe('run', () => {
  it('should create readline interface', () => {
    let readline = jasmine.createSpyObj('readline', ['createInterface']);

    game.run();

    expect(readline.createInterface).toHaveBeenCalled();
  });
});

Anyone has a suggestion?