使用AVA和Avoriaz在Vue.js中测试计算属性

Question

我正在尝试使用AVA和Avoriaz测试Vue.js组件的计算属性.我可以挂载组件并访问数据属性.

当我尝试访问计算属性时,该函数似乎没有该组件上的数据的范围.

computed: {
  canAdd() {
    return this.crew.firstName !== '' && this.crew.lastName !== '';
  }

我得到的错误是 Error: Cannot read property 'firstName' of undefined

测试文件:

import Vue from 'vue';
import { mount }
from 'avoriaz';
import test from 'ava';
import nextTick from 'p-immediate';
import ComputedPropTest from '../../../js/vue-components/computed_prop_test.vue';

Vue.config.productionTip = false;

test.only('Should handle computed properties', async(t) => {
  const MOCK_PROPS_DATA = {
      propsData: {
        forwardTo: '/crew',
        crew: {}
      }
    },
    wrapper = mount(ComputedPropTest, MOCK_PROPS_DATA),
    DATA = {
      crew: {
        firstName: 'Ryan',
        lastName: 'Gill'
      }
    };

  wrapper.setData(DATA);
  await nextTick();

  console.log('firstName: ', wrapper.data().crew.firstName); // Ryan

  console.log('isTrue: ', wrapper.computed().isTrue()); // true
  console.log('canAdd: ', wrapper.computed().canAdd()); // Errors

  t.true(wrapper.computed().isTrue());
});

零件:

<template>
  <div>
    <label for="firstName" class="usa-color-text-primary">First Name
      <i class="tooltipTextIcon fa fa-info-circle usa-color-text-gray" title="First name of crew."></i>
      <span class="required usa-additional_text usa-color-text-secondary-dark">Required</span>
    </label>
    <input id="firstName" type="text" class="requiredInput" name="firstName" v-model="crew.firstName" autofocus>
    <label for="lastName" class="usa-color-text-primary">Last Name
      <i class="tooltipTextIcon fa fa-info-circle usa-color-text-gray" title="Last name of crew."></i>
      <span class="required usa-additional_text usa-color-text-secondary-dark">Required</span>
    </label>
    <input id="lastName" type="text" class="requiredInput" name="lastName" v-model="crew.lastName" autofocus>
  </div>
</template>

<script>
  export default {
    name: 'crew-inputs',
    data() {
      return {
        crew: {
          firstName: '',
          lastName: ''
        }
      }
    },
    computed: {
      canAdd() {
        return this.crew.firstName !== '' && this.crew.lastName !== '';
      },
      isTrue() {
        return true;
      }
    }
  }
</script>

在isTrue计算财产似乎工作,但不依赖于任何在组件中的数据.

Answer 1

问题

怎么了？

经过长时间的观察和讨论,看起来this计算的getter 的上下文被设置为意外的东西.由于意外的this上下文,this不再引用Vue实例,导致组件属性无法访问.

您正在通过运行时错误来见证这一点

Error: Cannot read property 'firstName' of undefined

为什么会这样？

如果没有深入了解Avoriaz和Vue是如何工作的,我们无法知道.我确实尝试使用以下最小,完整和可验证的示例进行更深入的调查.您或其他人可能希望深入了解它.

'use-strict';

import Vue from 'vue';
import { mount } from 'avoriaz';

const FooBar = {
  template: `
    <div>{{ foobar }}</div>
  `,

  data() {
    return {
      foo: 'foo',
      bar: 'bar',
    };
  },

  computed: {
    foobar() {
      debugger;
      return `${this.foo} ${this.bar}`;
    },
  },
};

const vueMountedCt = new Vue(FooBar).$mount();
const vueMountedVm = vueMountedCt;

const avoriazMountedCt = mount(FooBar);
const avoriazMountedVm = avoriazMountedCt.vm;

/**
 * Control case, accessing component computed property in the usual way as documented by Vue.
 *
 * @see {@link https://vuejs.org/v2/guide/computed.html}
 *
 * Expectation from log: 'foobar' (the result of the computed property)
 * Actual result from log: 'foobar'
 */
console.log(vueMountedVm.foobar);

/**
 * Reproduce Avoriaz's method of accessing a Vue component's computed properties.
 * Avoriaz returns the Vue instance's `$option.computed` when calling `wrapper.computed()`.
 *
 * @see {@link https://github.com/eddyerburgh/avoriaz/blob/9882f286e7476cd51fe069946fee23dcb2c4a3e3/src/Wrapper.js#L50}
 *
 * Expectation from log: 'foobar' (the result of the computed property)
 * Actual result from log: 'undefined undefined'
 */
console.log(vueMountedVm.$options.computed.foobar());

/**
 * Access Vue component computed property via Avoriaz's documented method.
 *
 * @see {@link https://eddyerburgh.gitbooks.io/avoriaz/content/api/mount/computed.html}
 *
 * Expectation from log: 'foobar' (the result of the computed property)
 * Actual result from log: 'undefined undefined'
 */
console.log(avoriazMountedCt.computed().foobar());

一些观察:

• 查看控件案例的调用堆栈(案例1),您可以看到Vue的内部设置将this上下文设置为Vue实例.

Run Code Online (Sandbox Code Playgroud)

也可能建议您在Avoriaz和/或Vue中打开问题.