jest快照测试demo(vue)

1.vue create xx

 2.选择jest

.

3.执行npm run test:unit

结果：

 4.快照测试：

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

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

再次执行：

npm run test:unit

 第一次运行后，Jest 将在与原始测试所在的目录中生成一个__ snapshots __目录。让我们来看看新生成的快照。

// Jest Snapshot v1, https://goo.gl/fbAQLP

exports[`HelloWorld.vue renders props.msg when passed 1`] = `
<div class="hello">
  <h1>new message</h1>
  <p>
    For a guide and recipes on how to configure / customize this project,<br>
    check out the
    <a href="https://cli.vuejs.org" target="_blank" rel="noopener">vue-cli documentation</a>.
  </p>
  <h3>Installed CLI Plugins</h3>
  <ul>
    <li><a href="https://github.com/vuejs/vue-cli/tree/dev/packages/%40vue/cli-plugin-babel" target="_blank" rel="noopener">babel</a></li>
    <li><a href="https://github.com/vuejs/vue-cli/tree/dev/packages/%40vue/cli-plugin-eslint" target="_blank" rel="noopener">eslint</a></li>
    <li><a href="https://github.com/vuejs/vue-cli/tree/dev/packages/%40vue/cli-plugin-unit-jest" target="_blank" rel="noopener">unit-jest</a></li>
  </ul>
  <h3>Essential Links</h3>
  <ul>
    <li><a href="https://vuejs.org" target="_blank" rel="noopener">Core Docs</a></li>
    <li><a href="https://forum.vuejs.org" target="_blank" rel="noopener">Forum</a></li>
    <li><a href="https://chat.vuejs.org" target="_blank" rel="noopener">Community Chat</a></li>
    <li><a href="https://twitter.com/vuejs" target="_blank" rel="noopener">Twitter</a></li>
    <li><a href="https://news.vuejs.org" target="_blank" rel="noopener">News</a></li>
  </ul>
  <h3>Ecosystem</h3>
  <ul>
    <li><a href="https://router.vuejs.org" target="_blank" rel="noopener">vue-router</a></li>
    <li><a href="https://vuex.vuejs.org" target="_blank" rel="noopener">vuex</a></li>
    <li><a href="https://github.com/vuejs/vue-devtools#vue-devtools" target="_blank" rel="noopener">vue-devtools</a></li>
    <li><a href="https://vue-loader.vuejs.org" target="_blank" rel="noopener">vue-loader</a></li>
    <li><a href="https://github.com/vuejs/awesome-vue" target="_blank" rel="noopener">awesome-vue</a></li>
  </ul>
</div>
`;

Jest 在每个步骤都渲染 Vue 组件，并将其渲染状态保存为纯文本。下次运行测试时，如果渲染的组件的任何部分发生更改，则测试将失败并指出差异。

如果您想要更改组件的行为，则需要重新生成这些快照。为此，请运行：

npm run test:unit -- -u