Question

69

Jest URL.createObjectURL is not a function

rated 0 times [ 73] [ 4] / answers: 1 / hits: 75854 / 6 Years ago, wed, october 24, 2018, 12:00:00

I'm developping a reactJs application. I'm using jest to test my application.
I want to test a function that download a blob.

But unfortunately I receve this error:

URL.createObjectURL is not a function

my test function:

describe('download', () => {

    const documentIntial = { content: 'aaa' };

    it('msSaveOrOpenBlob should not have been called when navigao is undefined', () => {

      window.navigator.msSaveOrOpenBlob = null;

      download(documentIntial);

      expect(window.navigator.msSaveOrOpenBlob).toHaveBeenCalledTimes(0);

    });

  });

The function I want to test:

export const download = document => {

  const blob = new Blob([base64ToArrayBuffer(document.content)], {

    type: 'application/pdf',

  });

  if (window.navigator && window.navigator.msSaveOrOpenBlob) {

    window.navigator.msSaveOrOpenBlob(blob);

    return;

  }



  const fileURL = URL.createObjectURL(blob);

  window.open(fileURL);

};

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harrisonnelsonb

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2 Years ago

answered 6 Years ago jaredsages · Accepted Answer

This would appear to be as simple as setting up URL on the Global in Jest. Something like

describe('download', () => {

  const documentIntial = { content: 'aaa' };

  global.URL.createObjectURL = jest.fn();

  it('msSaveOrOpenBlob should not have been called when navigao is undefined', () => {

    global.URL.createObjectURL = jest.fn(() => 'details');

window.navigator.msSaveOrOpenBlob = jest.fn(() => 'details');

download(documentIntial);

expect(window.navigator.msSaveOrOpenBlob).toHaveBeenCalledTimes(1);

  });

});

This should result in a test that you can also use for checking if global.URL.createObjectURL was called. As a side note: you may also run into a similar issue with window.open I would suggest mocking that as well if this becomes the case.