Jest test fail when upgrading from v13.8.0 to v13.9.0

[pkrucz00]

Summary

A lot of tests in our app fail after upgrading the polaris version from 13.8.0 to 13.9.0 with an error:

ReferenceError: ResizeObserver is not defined

This should not happen after a minor upgrade.

Expected behavior

The tests pass after an minor upgrade.

Actual behavior

PlacementForm › fetches placement data if placement is edited

    ReferenceError: ResizeObserver is not defined

      94 |     (ReactRouterDom.useParams as jest.Mock).mockReturnValue({ id: '1' });
      95 |
    > 96 |     act(() => {
         |        ^
      97 |       renderComponent();
      98 |     });
      99 |     await new Promise(process.nextTick);

      at ../../node_modules/@shopify/polaris/build/cjs/components/Popover/Popover.js:97:22
      at commitHookEffectListMount (../../node_modules/react-dom/cjs/react-dom.development.js:23189:26)
      at commitPassiveMountOnFiber (../../node_modules/react-dom/cjs/react-dom.development.js:24970:11)
      at commitPassiveMountEffects_complete (../../node_modules/react-dom/cjs/react-dom.development.js:24930:9)
      at commitPassiveMountEffects_begin (../../node_modules/react-dom/cjs/react-dom.development.js:24917:7)
      at commitPassiveMountEffects (../../node_modules/react-dom/cjs/react-dom.development.js:24905:3)
      at flushPassiveEffectsImpl (../../node_modules/react-dom/cjs/react-dom.development.js:27078:3)
      at flushPassiveEffects (../../node_modules/react-dom/cjs/react-dom.development.js:27023:14)
      at performSyncWorkOnRoot (../../node_modules/react-dom/cjs/react-dom.development.js:26115:3)
      at flushSyncCallbacks (../../node_modules/react-dom/cjs/react-dom.development.js:12042:22)
      at commitRootImpl (../../node_modules/react-dom/cjs/react-dom.development.js:26998:3)
      at commitRoot (../../node_modules/react-dom/cjs/react-dom.development.js:26721:5)
      at finishConcurrentRender (../../node_modules/react-dom/cjs/react-dom.development.js:26020:9)
      at performConcurrentWorkOnRoot (../../node_modules/react-dom/cjs/react-dom.development.js:25848:7)
      at flushActQueue (../../node_modules/react/cjs/react.development.js:2667:24)
      at act (../../node_modules/react/cjs/react.development.js:2582:11)
      at ../../node_modules/@testing-library/react/dist/act-compat.js:47:25
      at Object.<anonymous> (src/components/PlacementForm/__tests__/index.test.tsx:96:8)
      ```

### Steps to reproduce

1. Create tests with Polaris elements and run them

### Are you using React components?

Yes

### Polaris version number

13.9.0

### Browser

_No response_

### Device

MacBook

[pkrucz00]

The problem still persists. Could you take a look at this issue? This prevents us from using the newest version of the Polaris dependency.

[dpanov]

@pkrucz00, some Polaris components now use ResizeObserver, so you'll need to mock it for your tests.

  global.ResizeObserver = jest.fn().mockImplementation(() => ({
    observe: jest.fn(),
    unobserve: jest.fn(),
    disconnect: jest.fn(),
  }));

Add this in the file that you pass to setupFilesAfterEnv in your jest.config.js and it should do the job.

[pkrucz00]

OK, this helped. Thank you!