如何模拟 google datalayer.push 回调 function？

Question

The snippet below displays my React hook file that runs Google Optimize AB test.

export default function useGetABExperimentType(experimentId) {
  const [experimentType, setExperimentType] = useState('0');

  useEffect(() => {
    if (window && window.dataLayer) {
      window.dataLayer.push({
        event: 'optimize.activate',
        eventCallback: () => {
          mySideEffectFunction();
        },
      });
    }
  }, []);

  return experimentType;
}

I am trying to test that my mySideEffectFunction() function does call to increase test coverage. In Jest, how do I mock the eventCallback callback function from window.dataLayer.push ?

Answer 1

    window.dataLayer = {
      push: jest.fn().mockImplementation(config => {
        config.eventCallback();
      }),
    };

I managed to mock and call the callback with this.

Answer 2

so in tests we refer to the window as global . so you could try mocking like this:

declare global {
    interface Window {
        dataLayer: {
           push: jest.fn().mockImplementation(() => {
                         eventCallback: jest.fn()
                 })
        }
    }
}

I haven't tested this but essentially mocking the dataLayer object and then mocking the functions inside it and mocking the implementations. then you should be able to test if the mocked function was called or not