TypeError: Cannot redefine property: ResizeObserver (v1.4.0)

[DesselBane]

Hi

with version 1.4.0 this error starts to appear.

Node version 14.20.0
Jest version 27.5.1
jsdom => jest-environment-jsdom@27.5.1

 FAIL  src/components/object-message/object-message.unit.js
  ● Test suite failed to run

    TypeError: Cannot redefine property: ResizeObserver
        at Function.defineProperty (<anonymous>)

       6 | import { click, getByText, mountToDom } from '@testutils'
       7 |
    >  8 | const resizeObserverMock = mockResizeObserver()
         |                            ^
       9 |
      10 | jest.mock('lodash/debounce', () => {
      11 |   return jest.fn((fn) => fn)

      at mockResizeObserver (node_modules/jsdom-testing-mocks/src/mocks/resize-observer.ts:101:10)
      at Object.<anonymous> (src/components/object-message/object-message.unit.js:8:28)
      at TestScheduler.scheduleTests (node_modules/@jest/core/build/TestScheduler.js:333:13)
      at runJest (node_modules/@jest/core/build/runJest.js:404:19)
      at _run10000 (node_modules/@jest/core/build/cli/index.js:320:7)
      at runCLI (node_modules/@jest/core/build/cli/index.js:173:3)

[trurl-master]

Hi there! Thank you for the issue.

A wild guess here. It seems that in your case the ResizeObserver is already defined. A polyfill maybe? Another mock? The cannot redefine property error would arise if the polyfill was applied, in such manner, for example:

  Object.defineProperty(window, 'ResizeObserver', {
    writable: true,
    configurable: false,
    value: PolyfilledResizeObserverClass,
  });

Note the configurable: false. In that case my code wouldn't be able to redefine it. Can you check if it's the case, please? I changed how I mock the ResizeObserver class from basically:

window.ResizeObserver = MockedResizeObserver

to

  Object.defineProperty(window, 'ResizeObserver', {
    writable: true,
    configurable: true,
    value: MockedResizeObserver,
  });

Because it is the recommended way, but maybe isn't the best.

Maybe you can disable the polyfill for tests somehow?

[trurl-master]

Will close this for now. Feel free to reopen if needed