`TypeError: _ref2.getBoundingClientRect is not a function` when unit testing code

[wojtekmaj]

Description

Despite .getBoundingClientRect() working just fine in an actual runtime, it appears to be undefined (and thus, crashing unexpectedly when called) in Jest tests:

TypeError: _ref.getBoundingClientRect is not a function

      at getBoundingClientRect (App.tsx:26:26)

This error might also appear as:

    AggregateError:

      at aggregateErrors (node_modules/react/cjs/react.development.js:552:11)
      at node_modules/react/cjs/react.development.js:860:40

because of poor aggregateErrors implementation that, as pictured, does not provide actual error messages.

Steps to reproduce

1. Run yarn test in reproducer
2. 💥

React Native Version

0.83.0

Affected Platforms

Other (please specify)

Output of npx @react-native-community/cli info

info Fetching system and libraries information...
System:
  OS: macOS 26.1
  CPU: (10) arm64 Apple M1 Max
  Memory: 1.09 GB / 64.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 24.11.1
    path: /usr/local/bin/node
  Yarn:
    version: 4.12.0
    path: /usr/local/bin/yarn
  npm:
    version: 11.6.2
    path: /usr/local/bin/npm
  Watchman: Not Found
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.2
      - iOS 26.2
      - macOS 26.2
      - tvOS 26.2
      - visionOS 26.2
      - watchOS 26.2
  Android SDK: Not Found
IDEs:
  Android Studio: Not Found
  Xcode:
    version: 26.2/17C52
    path: /usr/bin/xcodebuild
Languages:
  Java: Not Found
  Ruby:
    version: 2.6.10
    path: /usr/bin/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.0.0
    wanted: 20.0.0
  react:
    installed: 19.2.0
    wanted: 19.2.0
  react-native:
    installed: 0.83.0
    wanted: 0.83.0
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: Not found
  newArchEnabled: false

Stacktrace or Logs

TypeError: _ref.getBoundingClientRect is not a function

      24 |         }
      25 |
    > 26 |         const rect = ref.getBoundingClientRect();
         |                          ^
      27 |
      28 |         console.log(rect);
      29 |       }}

      at getBoundingClientRect (App.tsx:26:26)
      at commitAttachRef (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:9763:44)
      at runWithFiberInDEV (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:2315:13)
      at safelyAttachRef (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:9781:9)
      at commitLayoutEffectOnFiber (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:10083:26)
      at recursivelyTraverseLayoutEffects (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:10892:11)
      at commitLayoutEffectOnFiber (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:10005:11)
      at recursivelyTraverseLayoutEffects (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:10892:11)
      at commitLayoutEffectOnFiber (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:10005:11)
      at recursivelyTraverseLayoutEffects (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:10892:11)
      at commitLayoutEffectOnFiber (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:10087:11)
      at flushLayoutEffects (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:13774:15)
      at commitRoot (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:13697:9)
      at performWorkOnRoot (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:12336:15)
      at performWorkOnRootViaSchedulerTask (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:2908:7)
      at flushActQueue (node_modules/react/cjs/react.development.js:590:34)
      at Object.<anonymous>.process.env.NODE_ENV.exports.act (node_modules/react/cjs/react.development.js:884:10)
      at Object.act (__tests__/App.test.tsx:10:27)
      at asyncGeneratorStep (node_modules/@babel/runtime/helpers/asyncToGenerator.js:3:17)
      at _next (node_modules/@babel/runtime/helpers/asyncToGenerator.js:17:9)
      at node_modules/@babel/runtime/helpers/asyncToGenerator.js:22:7
      at Object.<anonymous> (node_modules/@babel/runtime/helpers/asyncToGenerator.js:14:12)

MANDATORY Reproducer

https://github.com/wojtekmaj/react-native-undefined-get-bounding-client-rect

Screenshots and Videos

No response