Jest学习笔记（3）-- 创建带有测试环境的vue应用

几多
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使用VueCli创建项目

  • 执行命令vue create vue-jest-demo
  • 配置选择

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  • jest.config.js默认配置 \node_modules\@vue\cli-plugin-unit-jest\presets\default

快速体验

  • html

  • 返回 Wrapper DOM 节点的 HTML 字符串。
// 挂载组件
import { shallowMount } from '@vue/test-utils'
import HelloWorld from '@/components/HelloWorld.vue'

test('HelloWorld.vue', () => {
  // 挂载组件
  const wrapper = shallowMount(HelloWorld, {
    propsData: {
      msg: 'Hello world'
    }
  });
  // console.log(wrapper.element.innerHTML)
  console.log(wrapper.html())
  expect(wrapper.html()).toContain('Hello world');
})

image.png

模拟用户点击

// HelloWorld.vue
<div class="hello">
    <button @click="count += 1">点击</button>
    <p data-testid="count-text">{{ count }}</p>
    <h1>{{ msg }}</h1>
</div>
<script>
export default {
  name: 'HelloWorld',
  props: {
    msg: String
  },
  data() {
    return {
      count: 0
    }
  }
}
</script>

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

test('HelloWorld.vue', () => {
  // 挂载组件
  const wrapper = shallowMount(HelloWorld, {
    propsData: {
      msg: 'Hello world'
    }
  });
  const btn = wrapper.find('button');
  // 触发事件
  btn.trigger('click');
  expect(wrapper.vm.count).toBe(1);
})
  • 为了测试计数器中的文本是否已经更新，我们需要了解 nextTick

使用 nextTick 与 await

  • 任何导致操作 DOM 的改变都应该在断言之前 await nextTick 函数。因为 Vue 会对未生效的 DOM 进行批量异步更新，避免因数据反复变化而导致不必要的渲染。
// 挂载组件
import { shallowMount } from '@vue/test-utils'
import HelloWorld from '@/components/HelloWorld.vue'
import Vue from 'vue'

test('HelloWorld.vue', async () => {
  // 挂载组件
  const wrapper = shallowMount(HelloWorld, {
    propsData: {
      msg: 'Hello world'
    }
  });
  // 找到count 的 p标签
  const countText = wrapper.find('[data-testid="count-text"]');
  const btn = wrapper.find('button');
  // 触发之前count为0
  expect(countText.text()).toBe('0');

  // 触发事件
  btn.trigger('click');

  await Vue.nextTick();

  expect(wrapper.vm.count).toBe(1);
  expect(countText.text()).toBe('1');
})

image.png

  • 也可以这么写
// 触发事件
  await btn.trigger('click');

  // await Vue.nextTick();

断言触发的事件

  • 每个挂载的包裹器都会通过其背后的 Vue 实例自动记录所有被触发的事件。你可以用 wrapper.emitted() 方法取回这些事件记录
<button data-testid="btn-emit" @click="$emit('handleClick', 'test123')">
    测试emit
</button>

const emitBtn = wrapper.find('[data-testid="btn-emit"]');
// 第1次触发emit
await emitBtn.trigger('click');
// 第2次触发emit
wrapper.vm.$emit('handleClick');
// 断言事件已经被触发
expect(wrapper.emitted().handleClick).toBeTruthy();

// 断言事件的有效数据 [ [ 'test123' ] ]
expect(wrapper.emitted().handleClick[0][0]).toBe('test123');

// 断言事件的数量
expect(wrapper.emitted().handleClick.length).toBe(2);

其他API

浅渲染和深渲染

  • 浅渲染

    • 在测试用例中，我们通常希望专注在一个孤立的单元中测试组件，避免对其子组件的行为进行间接的断言。

    • 额外的，对于包含许多子组件的组件来说，整个渲染树可能会非常大。重复渲染所有的子组件可能会让我们的测试变慢。

    • Vue Test Utils 允许你通过 shallowMount 方法只挂载一个组件而不渲染其子组件 (即保留它们的存根)

<template>
  <div>
    Foo组件
  </div>
</template>

<script>
  export default {

  }
</script>

<style lang="scss" scoped>

</style>

// 在HelloWorld.vue中引入并使用
import Foo from './Foo'


test.only('HelloWorld.vue', () => {
  // 浅渲染 只渲染HellWorld组件 子组件不渲染
  const shallowMountWrapper = shallowMount(HelloWorld);
  // 深渲染
  const mountWrapper = mount(HelloWorld);
  console.log('shallowMountWrapper', shallowMountWrapper.html());
  console.log('mountWrapper', mountWrapper.html());
})

image.png

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Vue和TDD 开发案例

  • 通过MVCTodos来驱动测试

image.png

  • D:\Desktop\Code\JestTest\vue-jest-demo\src\components\TodoApp\index.vue
<template>
  <section class="todoapp">
    <TodoHeader />
    <section class="main">
      <input id="toggle-all" class="toggle-all" type="checkbox" />
      <label for="toggle-all">Mark all as complete</label>
      <ul class="todo-list">
        <TodoItem />
        <TodoItem />
      </ul>
    </section>
    <TodoFooter />
  </section>
</template>

<script>
import TodoHeader from './TodoHeader.vue';
import TodoFooter from './TodoFooter.vue';
import TodoItem from './TodoItem.vue';
export default {
  name: 'TodoApp',
  components: {
    TodoHeader,
    TodoFooter,
    TodoItem,
  }
}
</script>
  • TodoHeader.vue
<template>
  <header class="header">
    <h1>todos</h1>
    <input class="new-todo" placeholder="What needs to be done?" autofocus />
  </header>
</template>

<script>
  export default {
    name: 'TodoHeader'
  }
</script>

<style lang="scss" scoped>

</style>
  • TodoItem.vue
<template>
  <li>
    <div class="view">
      <input class="toggle" type="checkbox" />
      <label>Buy a unicorn</label>
      <button class="destroy"></button>
    </div>
    <input class="edit" value="Rule the web" />
  </li>
</template>

<script>
  export default {
    name: 'TodoItem'
  }
</script>

<style lang="scss" scoped>

</style>
  • TodoFooter.vue
<template>
  <footer class="footer">
    <!-- This should be `0 items left` by default -->
    <span class="todo-count"><strong>0</strong> item left</span>
    <!-- Remove this if you don't implement routing -->
    <ul class="filters">
      <li>
        <a class="selected" href="#/">All</a>
      </li>
      <li>
        <a href="#/active">Active</a>
      </li>
      <li>
        <a href="#/completed">Completed</a>
      </li>
    </ul>
    <!-- Hidden if no completed items are left ↓ -->
    <button class="clear-completed">Clear completed</button>
  </footer>
</template>

<script>
  export default {
    name: 'TodoFooter'
  }
</script>

<style lang="scss" scoped>

</style>
  • D:\Desktop\Code\JestTest\vue-jest-demo\src\style\index.css
html,
body {
	margin: 0;
	padding: 0;
}

button {
	margin: 0;
	padding: 0;
	border: 0;
	background: none;
	font-size: 100%;
	vertical-align: baseline;
	font-family: inherit;
	font-weight: inherit;
	color: inherit;
	-webkit-appearance: none;
	appearance: none;
	-webkit-font-smoothing: antialiased;
	-moz-osx-font-smoothing: grayscale;
}

body {
	font: 14px 'Helvetica Neue', Helvetica, Arial, sans-serif;
	line-height: 1.4em;
	background: #f5f5f5;
	color: #111111;
	min-width: 230px;
	max-width: 550px;
	margin: 0 auto;
	-webkit-font-smoothing: antialiased;
	-moz-osx-font-smoothing: grayscale;
	font-weight: 300;
}

.hidden {
	display: none;
}

.todoapp {
	background: #fff;
	margin: 130px 0 40px 0;
	position: relative;
	box-shadow: 0 2px 4px 0 rgba(0, 0, 0, 0.2),
	            0 25px 50px 0 rgba(0, 0, 0, 0.1);
}

.todoapp input::-webkit-input-placeholder {
	font-style: italic;
	font-weight: 400;
	color: rgba(0, 0, 0, 0.4);
}

.todoapp input::-moz-placeholder {
	font-style: italic;
	font-weight: 400;
	color: rgba(0, 0, 0, 0.4);
}

.todoapp input::input-placeholder {
	font-style: italic;
	font-weight: 400;
	color: rgba(0, 0, 0, 0.4);
}

.todoapp h1 {
	position: absolute;
	top: -140px;
	width: 100%;
	font-size: 80px;
	font-weight: 200;
	text-align: center;
	color: #b83f45;
	-webkit-text-rendering: optimizeLegibility;
	-moz-text-rendering: optimizeLegibility;
	text-rendering: optimizeLegibility;
}

.new-todo,
.edit {
	position: relative;
	margin: 0;
	width: 100%;
	font-size: 24px;
	font-family: inherit;
	font-weight: inherit;
	line-height: 1.4em;
	color: inherit;
	padding: 6px;
	border: 1px solid #999;
	box-shadow: inset 0 -1px 5px 0 rgba(0, 0, 0, 0.2);
	box-sizing: border-box;
	-webkit-font-smoothing: antialiased;
	-moz-osx-font-smoothing: grayscale;
}

.new-todo {
	padding: 16px 16px 16px 60px;
	height: 65px;
	border: none;
	background: rgba(0, 0, 0, 0.003);
	box-shadow: inset 0 -2px 1px rgba(0,0,0,0.03);
}

.main {
	position: relative;
	z-index: 2;
	border-top: 1px solid #e6e6e6;
}

.toggle-all {
	width: 1px;
	height: 1px;
	border: none; /* Mobile Safari */
	opacity: 0;
	position: absolute;
	right: 100%;
	bottom: 100%;
}

.toggle-all + label {
	display: flex;
	align-items: center;
	justify-content: center;
	width: 45px;
	height: 65px;
	font-size: 0;
	position: absolute;
	top: -65px;
	left: -0;
}

.toggle-all + label:before {
	content: '❯';
	display: inline-block;
	font-size: 22px;
	color: #949494;
	padding: 10px 27px 10px 27px;
	-webkit-transform: rotate(90deg);
	transform: rotate(90deg);
}

.toggle-all:checked + label:before {
	color: #484848;
}

.todo-list {
	margin: 0;
	padding: 0;
	list-style: none;
}

.todo-list li {
	position: relative;
	font-size: 24px;
	border-bottom: 1px solid #ededed;
}

.todo-list li:last-child {
	border-bottom: none;
}

.todo-list li.editing {
	border-bottom: none;
	padding: 0;
}

.todo-list li.editing .edit {
	display: block;
	width: calc(100% - 43px);
	padding: 12px 16px;
	margin: 0 0 0 43px;
}

.todo-list li.editing .view {
	display: none;
}

.todo-list li .toggle {
	text-align: center;
	width: 40px;
	/* auto, since non-WebKit browsers doesn't support input styling */
	height: auto;
	position: absolute;
	top: 0;
	bottom: 0;
	margin: auto 0;
	border: none; /* Mobile Safari */
	-webkit-appearance: none;
	appearance: none;
}

.todo-list li .toggle {
	opacity: 0;
}

.todo-list li .toggle + label {
	/*
		Firefox requires `#` to be escaped - https://bugzilla.mozilla.org/show_bug.cgi?id=922433
		IE and Edge requires *everything* to be escaped to render, so we do that instead of just the `#` - https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/7157459/
	*/
	background-image: url('data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%22http%3A//www.w3.org/2000/svg%22%20width%3D%2240%22%20height%3D%2240%22%20viewBox%3D%22-10%20-18%20100%20135%22%3E%3Ccircle%20cx%3D%2250%22%20cy%3D%2250%22%20r%3D%2250%22%20fill%3D%22none%22%20stroke%3D%22%23949494%22%20stroke-width%3D%223%22/%3E%3C/svg%3E');
	background-repeat: no-repeat;
	background-position: center left;
}

.todo-list li .toggle:checked + label {
	background-image: url('data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2240%22%20height%3D%2240%22%20viewBox%3D%22-10%20-18%20100%20135%22%3E%3Ccircle%20cx%3D%2250%22%20cy%3D%2250%22%20r%3D%2250%22%20fill%3D%22none%22%20stroke%3D%22%2359A193%22%20stroke-width%3D%223%22%2F%3E%3Cpath%20fill%3D%22%233EA390%22%20d%3D%22M72%2025L42%2071%2027%2056l-4%204%2020%2020%2034-52z%22%2F%3E%3C%2Fsvg%3E');
}

.todo-list li label {
	word-break: break-all;
	padding: 15px 15px 15px 60px;
	display: block;
	line-height: 1.2;
	transition: color 0.4s;
	font-weight: 400;
	color: #484848;
}

.todo-list li.completed label {
	color: #949494;
	text-decoration: line-through;
}

.todo-list li .destroy {
	display: none;
	position: absolute;
	top: 0;
	right: 10px;
	bottom: 0;
	width: 40px;
	height: 40px;
	margin: auto 0;
	font-size: 30px;
	color: #949494;
	transition: color 0.2s ease-out;
}

.todo-list li .destroy:hover,
.todo-list li .destroy:focus {
	color: #C18585;
}

.todo-list li .destroy:after {
	content: '×';
	display: block;
	height: 100%;
	line-height: 1.1;
}

.todo-list li:hover .destroy {
	display: block;
}

.todo-list li .edit {
	display: none;
}

.todo-list li.editing:last-child {
	margin-bottom: -1px;
}

.footer {
	padding: 10px 15px;
	height: 20px;
	text-align: center;
	font-size: 15px;
	border-top: 1px solid #e6e6e6;
}

.footer:before {
	content: '';
	position: absolute;
	right: 0;
	bottom: 0;
	left: 0;
	height: 50px;
	overflow: hidden;
	box-shadow: 0 1px 1px rgba(0, 0, 0, 0.2),
	            0 8px 0 -3px #f6f6f6,
	            0 9px 1px -3px rgba(0, 0, 0, 0.2),
	            0 16px 0 -6px #f6f6f6,
	            0 17px 2px -6px rgba(0, 0, 0, 0.2);
}

.todo-count {
	float: left;
	text-align: left;
}

.todo-count strong {
	font-weight: 300;
}

.filters {
	margin: 0;
	padding: 0;
	list-style: none;
	position: absolute;
	right: 0;
	left: 0;
}

.filters li {
	display: inline;
}

.filters li a {
	color: inherit;
	margin: 3px;
	padding: 3px 7px;
	text-decoration: none;
	border: 1px solid transparent;
	border-radius: 3px;
}

.filters li a:hover {
	border-color: #DB7676;
}

.filters li a.selected {
	border-color: #CE4646;
}

.clear-completed,
html .clear-completed:active {
	float: right;
	position: relative;
	line-height: 19px;
	text-decoration: none;
	cursor: pointer;
}

.clear-completed:hover {
	text-decoration: underline;
}

.info {
	margin: 65px auto 0;
	color: #4d4d4d;
	font-size: 11px;
	text-shadow: 0 1px 0 rgba(255, 255, 255, 0.5);
	text-align: center;
}

.info p {
	line-height: 1;
}

.info a {
	color: inherit;
	text-decoration: none;
	font-weight: 400;
}

.info a:hover {
	text-decoration: underline;
}

/*
	Hack to remove background from Mobile Safari.
	Can't use it globally since it destroys checkboxes in Firefox
*/
@media screen and (-webkit-min-device-pixel-ratio:0) {
	.toggle-all,
	.todo-list li .toggle {
		background: none;
	}

	.todo-list li .toggle {
		height: 40px;
	}
}

@media (max-width: 430px) {
	.footer {
		height: 50px;
	}

	.filters {
		bottom: 10px;
	}
}

:focus,
.toggle:focus + label,
.toggle-all:focus + label {
	box-shadow: 0 0 2px 2px #CF7D7D;
	outline: 0;
}
  • main.js
import './style/index.css'
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