ReferenceError: You are trying to `import` a file after the Jest environment has been torn down.

🐛 Bug Report

I have a component that makes use of Animated component from react native. I started writing a test case to simulate onPress of a component, which calls a function that has Animated.timing in it, and setState.

jest works fine, but the tests never stops running, and one unrelated test case that I’ve written before never seem to pass now (which passed before).

running jest --watch, I get this error:

ReferenceError: You are trying to `import` a file after the Jest environment has been torn down.

      at Function.bezier (node_modules/react-native/Libraries/Animated/src/Easing.js:113:21)
      at ease (node_modules/react-native/Libraries/Animated/src/Easing.js:34:24)
      at TimingAnimation._easing (node_modules/react-native/Libraries/Animated/src/Easing.js:133:18)
      at TimingAnimation.onUpdate (node_modules/react-native/Libraries/Animated/src/animations/TimingAnimation.js:107:45)

 RUNS  src/__tests__/SlideDownMenu.test.js

/home/nrion/Desktop/mobile-ui/PriceInsight_app/node_modules/react-native/Libraries/Animated/src/Easing.js:114
      return _bezier(x1, y1, x2, y2);
             ^
TypeError: _bezier is not a function
    at Function.bezier (/home/nrion/Desktop/mobile-ui/PriceInsight_app/node_modules/react-native/Libraries/Animated/src/Easing.js:224:12)
    at ease (/home/nrion/Desktop/mobile-ui/PriceInsight_app/node_modules/react-native/Libraries/Animated/src/Easing.js:94:21)
    at TimingAnimation._easing (/home/nrion/Desktop/mobile-ui/PriceInsight_app/node_modules/react-native/Libraries/Animated/src/Easing.js:255:16)
    at TimingAnimation.onUpdate (/home/nrion/Desktop/mobile-ui/PriceInsight_app/node_modules/react-native/Libraries/Animated/src/animations/TimingAnimation.js:138:14)
    at ontimeout (timers.js:386:11)
    at tryOnTimeout (timers.js:250:5)
    at Timer.listOnTimeout (timers.js:214:5)

Expected behavior

Tests passes

Link to repl or repo (highly encouraged)

repl.it demo: https://repl.it/repls/PartialGrimyMetadata

Run npx envinfo --preset jest

Environment:
  OS: Linux 4.14
  Node: 6.14.2
  Yarn: 1.7.0
  npm: 3.10.10
  Watchman: Not Found
  Xcode: N/A
  Android Studio: Not Found

[tarunjuneja]

I am on react-native 0.60 was struggling with same error

I solved it by adding jest.useFakeTimers();

With above it’s extremely important to understand this

jest.useFakeTimers() mocks out setTimeout and other timer functions with mock functions.

If running multiple tests inside of one file or describe block, jest.useFakeTimers(); can be called before each test manually or with a setup function such as beforeEach.

Not doing so will result in the internal usage counter not being reset.

[f4z3k4s]

I am using react-native-testing-library and what resolved this error for me was to simply make the callback of the test case async like

it('your test case', () => {...})

becomes:

it('your test case', async () => {...})