使用jest进行Vue测试：$route总是未定义的

npm install --save-dev jest vue-jest @vue/test-utils

module.exports = {
  moduleFileExtensions: [
    'js',
    'jsx',
    'json',
    'vue'
  ],
  transform: {
    '^.+\\.vue$': 'vue-jest',
    '^.+\\.js$': 'babel-jest'
  },
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/src/$1'
  },
  snapshotSerializers: [
    'jest-serializer-vue'
  ],
  testMatch: [
    '**/tests/unit/**/*.spec.(js|jsx|ts|tsx)|**/__tests__/*.(js|jsx|ts|tsx)'
  ],
  testURL: 'http://localhost/'
}

import { shallowMount } from '@vue/test-utils'
import ExampleComponent from '@/components/ExampleComponent.vue'

describe('ExampleComponent', () => {
  it('renders props.msg when passed', () => {
    const msg = 'new message'
    const wrapper = shallowMount(ExampleComponent, {
      propsData: { msg }
    })
    expect(wrapper.text()).toMatch(msg)
  })
})

npm run test:unit

const wrapper = shallowMount(ExampleComponent, {
  propsData: { msg },
  mocks: {
    $route: {
      path: '/example'
    }
  }
})