使用 vuejs-datepicker 运行 Jest 测试时出错

Question

我正在使用我的测试 Vue 应用程序学习 Jest，除了在我的一个 components 中我使用 vuejs-datepicker 并且当我运行下面的测试时，我得到了以下错误，我可以似乎没办法解决问题。

测试文件

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

import ShowBlogs from '@/components/showBlogs.vue'
import ActiveBlogs from '@/components/blogsActive.vue'
import AddBlog from '@/components/addBlog.vue'
import ClosedBlogs from '@/components/blogsClosed.vue'

describe('ShowBlogs.vue tests', () => {
    let wrapper = null

    beforeEach(() => {
        wrapper = mount(ShowBlogs)
    })

    afterEach(() => {
        wrapper.destroy()
    })

    it('Checks "ShowBlogs" component rendered', () => {
        expect(wrapper.name()).toMatch('ShowBlogs')
    })

    it('Checks "Active" tab displayed on load', () => {
        expect(wrapper.find(ActiveBlogs).exists()).toBeTruthy()
    })

    it('Checks tab labels & correct tab has "Active" class', () => {
        expect(wrapper.find('h1').text()).toEqual('Articles')

        expect(wrapper.findAll('li').length).toEqual(3)
        expect(wrapper.findAll('li').at(0).text()).toEqual('Active blogs')
        expect(wrapper.findAll('li').at(1).text()).toEqual('Closed blogs')
        expect(wrapper.findAll('li').at(2).text()).toEqual('Add a new blog')

        expect(wrapper.find('#activeBlogs-tab').classes()).toContain('active')
    })

    it('Checks "ClosedBlogs" component displayed when clicking "Closed Blogs tab"', () => {
        wrapper.find('#closedBlogs-tab').trigger('click')
        expect(wrapper.find(ClosedBlogs).exists()).toBeTruthy()
    })
})

错误

FAIL tests/unit/showBlogs.vue.spec.js ● 测试套件运行失败

Jest encountered an unexpected token

This usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript.

By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules".

Here's what you can do:
 • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.    
 • If you need a custom transformation specify a "transform" option in your config.
 • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config 

选项。

You'll find more details and examples of these config options in the docs:
https://jestjs.io/docs/en/configuration.html

Details:

C:\Users\anton\Desktop\testProject\vueproject\node_modules\vuejs-datepicker\dist\vuejs-datepicker.esm.js:2437
export default Datepicker;
^^^^^^

SyntaxError: Unexpected token 'export'

  116 | 
  117 | <script>
> 118 | import Datepicker from "vuejs-datepicker/dist/vuejs-datepicker.esm.js";
      | ^
  119 | //import * as lang from "vuejs-datepicker/src/locale";
  120 | import globalVars from "../mixins/globalVars";
  121 | import loader from './loader.vue';

  at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:537:17)
  at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:579:25)
  at src/components/addBlog.vue:118:1
  at Object.<anonymous> (src/components/addBlog.vue:232:3)

Package.json

{
  "name": "vueproject",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "serve": "vue-cli-service serve",
    "build": "vue-cli-service build",
    "test:unit": "vue-cli-service test:unit --watch",
    "test:e2e": "vue-cli-service test:e2e",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "apexcharts": "^3.16.0",
    "core-js": "^3.6.4",
    "firebase": "^7.9.3",
    "vue": "^2.6.11",
    "vue-apexcharts": "^1.5.2",
    "vue-moment": "^4.1.0",
    "vue-router": "^3.1.6",
    "vuefire": "^2.2.1",
    "vuejs-datepicker": "^1.6.2",
    "vuex": "^3.1.2"
  },
  "devDependencies": {
    "@babel/core": "^7.8.7",
    "@babel/preset-env": "^7.8.7",
    "@vue/cli-plugin-babel": "~4.2.0",
    "@vue/cli-plugin-e2e-cypress": "~4.2.0",
    "@vue/cli-plugin-eslint": "~4.2.0",
    "@vue/cli-plugin-router": "~4.2.0",
    "@vue/cli-plugin-unit-jest": "~4.2.0",
    "@vue/cli-plugin-vuex": "~4.2.0",
    "@vue/cli-service": "~4.2.0",
    "@vue/test-utils": "1.0.0-beta.31",
    "babel-eslint": "^10.0.3",
    "eslint": "^6.7.2",
    "eslint-plugin-vue": "^6.1.2",
    "vue-template-compiler": "^2.6.11"
  }
}

Jest.config

module.exports = {
  preset: '@vue/cli-plugin-unit-jest'
}

AddBlog.vue

<script>
import Datepicker from "vuejs-datepicker/dist/vuejs-datepicker.esm.js";
import globalVars from "../mixins/globalVars";
import loader from './loader.vue';
import moment from 'moment'
.......

Answer 1

当你运行测试时，Jest 会尝试在 lib DatePicker 中找到 css 文件，你应该模拟它。

按照以下步骤操作：

mkdir tests/__mocks__/ && touch tests/__mocks__/styleMock.js 

注意：文件 styleMock.js 将保持为空，因为该文件将是模拟 tmp 文件。

之后，需要在jest.config.js中添加配置

  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/src/$1',
    '\\.(css|less|sass|scss)$': '<rootDir>/tests/__mocks__/styleMock.js',
  },

最后，尝试再次运行您的测试 =)