CODEWITHSUNDEEP
javascriptreactjstestingblobjestjs
Melchia
Melchia

Reputation: 24314

Jest URL.createObjectURL is not a function

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);
};

Upvotes: 109

Views: 111655

Answers (8)

None of your Beez Wax
None of your Beez Wax

Reputation: 1383

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.

Upvotes: 106

Hard Monkey PC
Hard Monkey PC

Reputation: 63

this code simulates a blob url to test your full cycle

    global.URL.createObjectURL = jest.fn(
      (blob: any) => `blob:${blob.size}#t=${Date.now()}`
    )

Upvotes: 1

Jacque
Jacque

Reputation: 11

Using react-testing-library with jest:

I had to add jest.spyOn(URL, 'createObjectURL').mockImplementation(); inside my test. This worked in conjunction with creating a mock file for the dom object

Object.defineProperty(URL, 'createObjectURL', {writable: true, value: jest.fn()})

and adding the import statement for that mock file as the first import inside my testing file.

Note: the mock file cannot be inside the tests directory

Upvotes: 1

Lucas Wiman
Lucas Wiman

Reputation: 11297

The package jsdom-worker happens to provide this method, as well as adding support for web workers. The following worked for me:

npm install -D jsdom-worker

Then in package.json, edit or add a jest key:

{
  ...
  "jest": {
    "setupFiles": [
      "jsdom-worker"
    ]
  }
}

Upvotes: 7

Michael S
Michael S

Reputation: 880

Just mocking the function global.URL.createObjectURL did not work for me, because the function was used by some modules during import and I got the error Jest URL.createObjectURL is not a function during import.

Instead it did help to create a file mockJsdom.js

Object.defineProperty(URL, 'createObjectURL', {
  writable: true,
  value: jest.fn()
})

Then import this file as the first import in your file containing the test

import './mockJsdom'
import { MyObjects} from '../../src/lib/mylib'

test('my test', () => {
  // test code
}

Found here: https://jestjs.io/docs/manual-mocks#mocking-methods-which-are-not-implemented-in-jsdom

Upvotes: 9

Varun Pradhan
Varun Pradhan

Reputation: 607

You just have to Write this in your setupTest.js

window.URL.createObjectURL = function() {};

Upvotes: 19

jackdbd
jackdbd

Reputation: 5061

Since window.URL.createObjectURL is not (yet) available in jest-dom, you need to provide a mock implementation for it.

Don't forget to reset the mock implementation after each test.

describe("your test suite", () => {
  window.URL.createObjectURL = jest.fn();

  afterEach(() => {
    window.URL.createObjectURL.mockReset();
  });

  it("your test case", () => {
    expect(true).toBeTruthy();
  });
});

Upvotes: 37

Kaiido
Kaiido

Reputation: 137131

jsdom, the JavaScript implementation of the WHATWG DOM used by jest doesn't implement this method yet.

You can find an open ticket about this exact issue on their github page where some workarounds are provided in comments. But if you need the blobURL to actually work you'll have to wait this FR is solved.

Workaround proposed in the comments of the issue for jest:

function noOp () { }
if (typeof window.URL.createObjectURL === 'undefined') { 
  Object.defineProperty(window.URL, 'createObjectURL', { value: noOp})
}

Upvotes: 20

Related Questions