A guide on effectively mocking a Vuex store within the parentComponent of VueJS test-utils

I am currently using Jest in conjunction with vue-test-utils to test the reaction of a child component to an $emit event triggered by the parent component.

The VueJS test-utils library offers a parentComponent option that can be utilized when mounting or shallow mounting a component.

Although my setup is functioning correctly, I am encountering an issue where the parent component throws a

TypeError: Cannot read property 'state' of undefined

when it reaches a this.$store.state.something.here section within the code.

Is there a way to properly mock the Vuex store in this situation?

Here is how the component is mounted:

const wrapper = shallowMount(ChildComponent, {
  store,
  localVue,
  parentComponent: ParentComponent,
  mocks: {
    $t: msg => msg,
  },
});

Any suggestions on resolving this issue would be greatly appreciated.

Answer №1

After spending a significant amount of time debugging, I finally identified the issue that was causing problems. Although it may not provide a complete solution to the original poster's questions, I have decided to share my findings here in hopes of assisting someone else in the future.

The challenge I encountered involved attempting to mock and mount a specific component:

<template>
<div test="object-list-div">
  <h1 test="component-title">{{ objectName }}</h1>
  <table class="table">
    <thead>
        <tr test="table-row-title">
            <th scope="col" test="table-column-title" v-for="(value, name, index) in objectData[0]" :key="index">{{ name }}</th>
        </tr>
    </thead>
    <tbody>
      <tr test="table-row-data" v-for="(ivalue, iname, i) in objectData" :key="i">
        <td test="table-cell-data" v-for="(jvalue, jname, j) in ivalue" :key="j">{{ jvalue }}</td>
      </tr>
    </tbody>
  </table>
</div>

export default  {

    props: [
        'objectName',
        'objectData'
    ],
    computed: {
      visibleColums() {
        return this.$store.state.Config_ShowColumn;
      }
    }
}

The code snippet below shows the wrapper used for testing:

 wrapper = shallowMount(ObjectList, {
    mocks: {
      $store: {
        state: {
          Config_ShowColumn: [
            "Field1",
            "Field2",
            "Field3",
            "Field4",
            "Field5",
          ]
        }
      }
    }
  });

The error experienced by the original poster occurred because the component required two specific Props during initialization. Failing to provide these Props resulted in the component becoming unresponsive.

The updated working solution is as follows:

import { shallowMount } from "@vue/test-utils";
import { expect } from "chai";
import ObjectList from "@/components/Object-List.vue";  

wrapper = shallowMount(ObjectList, {
    propsData: {
      objectName: "Ticket",
      objectData: [
        {
          Field1: "Field1",
          Field2: "Field2",
          Field3: "Field3",
          Field4: "Field4",
          Field5: "Field5",
        },
      ]
    }, 
    mocks: {
      $store: {
        state: {
          Config_ShowColumn: [
            "Field1",
            "Field2",
            "Field3",
            "Field4",
            "Field5",
          ]
        }
      }
    }
  });

I hope this solution proves to be helpful for others facing similar challenges.

Answer №2

Even though Richard's suggestion was correct, I didn't have much luck with it initially.

The solution turned out to be much simpler than I had imagined. Instead of creating an instance of Vuex.Store, I just added the mocked $store in the vue-test-utils configuration like this:

import { createLocalVue, shallowMount, config } from '@vue/test-utils';

config.mocks.$store = {
  state: {
    user: {
      sexy: true
    },
  },
};

Since I only needed to mock the data and not use a real Vuex instance, this approach worked perfectly for me.

Answer №3

What method are you using to initialize the mock store? It should follow a format similar to

const options = {
  state: {...},
  getters: {...},
  mutations: {...}
}
const fakeStore = new Vuex.Store(options)

If this.$store is showing as undefined, my suspicion is that you may be mistakenly passing the options object directly to shallowMount.

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