vue test utils TypeError: Cannot destructure property `config` of 'undefined' or 'null'

Question

I'm doing just simple unit test with vue test utils. but It's not working. I've no clue.... help me

I installed this things.....

> $ npm i -D jest @vue/test-utils vue-jest jest-serializer-vue babel-jest babel-core@bridge

> $ npm i -D @babel/core @babel/preset-env

I made jest.config.js file

module.exports = {
  moduleFileExtensions: [
    'vue',
    'js'
  ],

  moduleNameMapper: {
    '^~/(.*)$': '<rootDir>/src/$1'
  },

  modulePathIgnorePatterns: [
    '<rootDir>/node_modules',
    '<rootDir>/dist'
  ],

  testURL: 'http://localhost',

  transform: {
    '^.+\\.vue$' : 'vue-jest',
    '^.+\\.jsx?$' : 'babel-jest'
  }
}

and tests/Parent.test.js

import { mount } from '@vue/test-utils'
import Parent from './Parent.vue'

test('Mount', () => {
  const wrapper = mount(Parent)
  expect(wrapper.html()).toBe('')
})

but npm run test:unit error like this

 FAIL  tests/Parent.test.js
  ● Test suite failed to run

    TypeError: Cannot destructure property `config` of 'undefined' or 'null'.

      at Object.getCacheKey (node_modules/vue-jest/lib/index.js:10:5)
      at ScriptTransformer._getCacheKey (node_modules/@jest/transform/build/ScriptTransformer.js:280:41)
      at ScriptTransformer._getFileCachePath (node_modules/@jest/transform/build/ScriptTransformer.js:351:27)
      at ScriptTransformer.transformSource (node_modules/@jest/transform/build/ScriptTransformer.js:588:32)
      at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:758:40)
      at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:815:19)

Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        0.512 s
Ran all test suites.

Answer 1

The package is moving away from semantic versioning to support a variety of Vue versions (2.x, 3.x) and Jest versions (26.x, 27.x). So, if you're using Vue 3.x and Jest 27.x, you need to install vue3-jest, not vue-jest.

npm i vue3-jest -D

# or

yarn add vue3-jest --dev

Then, update your jest.config.js as follows:

module.exports = {
  moduleFileExtensions: ['vue', 'js', 'json', 'jsx'],
  testEnvironment: 'jsdom',
  transform: {
    '^.+\\.vue$': 'vue3-jest',
    '^.+\\js$': 'babel-jest',
  },
}

By the time of writing this answer, the package naming & versioning was like so:

You can read more about the new naming & versioning strategy here.

Answer 2

If you're using version 27 of jest, try downgrading to version 26. Make sure to downgrade babel-jest and ts-jest as well to version 26. I was getting the following error and that did it for me:

Cannot destructure property 'config' of 'undefined' as it is undefined.