Jest: global.__reanimatedWorkletInit is not a function

Description

We’ve setup jest to snapshot-test components and functionality. I’ve installed reanimated v2 without problems and all tests ran perfectly. After creating some more complex animations and gestures, I found out that suddenly all tests failed with the same error:

Note that I never touched those components/tests after installing reanimated v2

Unfortunately I have no idea what exactly caused this, since the tests in our master branch still run successfully, and I also got some smaller animations implemented over there.

Screenshots

Steps To Reproduce

1. Install reanimated v2
2. Create some complex tests
3. Run jest

Expected behavior

My tests should run successfully.

Actual behavior

My tests fail. Even the ones I didn’t touch.

Snack or minimal code example

jest.setup.ts

const mock = jest.requireMock("react-native-reanimated");
jest.mock("react-native-reanimated", () => ({
  ...mock,
  useSharedValue: jest.fn().mockReturnValue(0),
  useAnimatedStyle: jest.fn().mockReturnValue({}),
  useAnimatedScrollHandler: jest.fn().mockReturnValue({}),
  createAnimatedComponent: (component) => jest.fn().mockReturnValue(component),
  __reanimatedWorkletInit: jest.fn(),
  ScrollView: "ScrollView",
}));

// ...

//@ts-expect-error
global.__reanimatedWorkletInit = jest.fn();

Package versions

• React: 16.13.1
• React Native: 0.63.3
• React Native Reanimated: 2.0.0-alpha.7
• @testing-library/jest-native: 3.4.3
• @testing-library/react-native: 7.0.2
• jest: 26.5.3
• NodeJS: v14.13.1

[M-i-k-e-l]

What worked for us was adding the following to the jest-setup.js file:

global.__reanimatedWorkletInit = jest.fn();

[nandorojo]

It looks like Reanimated 2.8 is breaking on Next.js, throwing this error: