Is there a way to adjust the state value in Pinia within a Vue3 component test, and have an impact on the component?

When testing the component using pinia with vue-test-utils, I encountered difficulty in modifying the state value stored in pinia. Despite trying multiple methods, I was unable to achieve the desired result. The original component and store files are provided below.

// HelloWorld.vue
<template>
    <h1>{{ title }}</h1>
</template>

<script>
import { useTestStore } from "@/stores/test";
import { mapState } from "pinia";

export default {
    name: "HelloWorld",
    
    computed: {
        ...mapState(useTestStore, ["title"]),
    },
};
</script>
// @/stores/test.js
import { defineStore } from "pinia";

export const useTestStore = defineStore("test", {
    state: () => {
        return { title: "hhhhh" };
    },
});

I attempted various methods to solve this issue:

  1. Importing the store into the test code and making direct changes, but the modifications did not reflect on the component.
// test.spec.js
import { mount } from "@vue/test-utils";
import { createTestingPinia } from "@pinia/testing";
import HelloWorld from "@/components/HelloWorld.vue";
import { useTestStore } from "@/stores/test";

test("pinia in component test", () => {
 const wrapper = mount(HelloWorld, {
     global: {
         plugins: [createTestingPinia()],
     },
 });
 const store = useTestStore();
 store.title = "xxxxx";

 console.log(wrapper.text()) //"hhhhh";
});
  1. Attempted to overwrite the original store by using initialState, but it also had no impact.
// test.spec.js
import { mount } from "@vue/test-utils";
import { createTestingPinia } from "@pinia/testing";
import HelloWorld from "@/components/HelloWorld.vue";

test("pinia in component test", () => {
 const wrapper = mount(HelloWorld, {
     global: {
         plugins: [createTestingPinia({ initialState: { title: "xxxxx" } })],
     },
 });
 console.log(wrapper.text()) //"hhhhh";
});
  1. Tried to modify the TestingPinia object passed to global.plugins in the test code, without any success.
// test.spec.js
import { mount } from "@vue/test-utils";
import { createTestingPinia } from "@pinia/testing";
import HelloWorld from "@/components/HelloWorld.vue";

test("pinia in component test", () => {
 const pinia = createTestingPinia();
 pinia.state.value.title = "xxxxx";
 const wrapper = mount(HelloWorld, {
     global: {
         plugins: [pinia],
     },
 });
 console.log(wrapper.text()) //"hhhhh";
});
  1. Utilized global.mocks to mock the states used in the component, which only worked for states passed in with setup(), while those passed in with mapState() were unaffected.
// test.spec.js
import { mount } from "@vue/test-utils";
import { createTestingPinia } from "@pinia/testing";
import HelloWorld from "@/components/HelloWorld.vue";

test("pinia in component test", () => {
 const wrapper = mount(HelloWorld, {
     global: {
         plugins: [createTestingPinia()],
         mocks: { title: "xxxxx" },
     },
 });
 console.log(wrapper.text()) //"hhhhh"
});

Answer №1

The issue was successfully resolved by implementing the jest.mock() method.

import { mount } from "@vue/test-utils";
import { createPinia } from "pinia";
import HelloWorld from "@/components/HelloWorld.vue";

jest.mock("@/stores/test", () => {
    const { defineStore } = require("pinia");
    const useTestStore = defineStore("test", { state: () => ({ title: "xxxxx" }) });
    return { useTestStore };
});

test("pinia in component test", () => {
    const wrapper = mount(HelloWorld, {
        global: { plugins: [createPinia()] },
    });
    expect(wrapper.text()).toBe("xxxxx");
});

Answer №2

To prevent future headaches, it's important to understand the role of the event loop in Vue reactivity. The event loop is crucial for triggering a chain reaction of state changes.

When using vue-test-utils to mount/shallowMount/render a component, the event loop does not run automatically. You must manually trigger it for reactivity to take effect, such as by using:

await component.vm.$nextTick;

If you prefer to avoid dealing with ticks, you'll need to mock the store state/getters/etc., as recommended by the documentation (although the reason behind this is not explicitly explained). In this case, the original poster mocked the entire store.

For more information, check out: Vue-test-utils: using $nextTick multiple times in a single test

Answer №3

Special thanks to Red Panda for bringing up this topic. Personally, I prefer using "testing-library" and "vue-testing-library" over "vue-test-utils" and "jest". However, I encountered an issue with changing the initial data of the pinia store. After some trial and error, I managed to find a solution without having to mock any functions. The key was to remember to await when you $patch the data. Somehow, that made all the difference. Here's how my code looks now and it works like a charm:

Popup.test.js

import { render, screen } from '@testing-library/vue'
import { createTestingPinia } from '@pinia/testing'
import { popup } from '@/store1/popup/index'
import Popup from '../../components/Popup/index.vue'

describe('Popup component', () => {
  test('displays popup with group component', async () => {
    render(Popup, {
      global: { plugins: [createTestingPinia()] }
    })
    const store = popup()
    await store.$patch({ popupData: 'new name' })
    screen.debug()
  })
})

Alternatively, you can set the initialState using this approach:

import { render, screen } from '@testing-library/vue'
import { createTestingPinia } from '@pinia/testing'
import { popup } from '@/store1/popup/index'
import Popup from '../../components/Popup/index.vue'

test('displays popup with no inner component', async () => {
    const { getByTestId } = render(Popup, {
        global: {
            plugins: [
                createTestingPinia({
                    initialState: {
                        popup: {
                            popupData: 'new name'
                        }
                    }
                })
            ]
        }
    })
    const store = popup()
    screen.debug()
})

In the initialState, the 'popup' represents the imported Pinia store from @/store1/popup. You can specify any other entities in a similar fashion.

Popup.vue

<script>
import { defineAsyncComponent, markRaw } from 'vue'
import { mapState, mapActions } from 'pinia'
import { popup } from '@/store1/popup/index'

export default {
  data() {
    return {}
  },
  computed: {
    ...mapState(popup, ['popupData'])
  },
....

https://i.sstatic.net/L29JQ.jpg

Answer №4

In my current Vue 3 project, I am utilizing the composition API for styling.

The Composition API serves dual purposes in my project - it is used for both creating components and defining the store.

Let me show you a snippet of my store:

player.js

import { defineStore } from 'pinia'
import { ref, reactive } from 'vue'

export const usePlayerStore = defineStore('player',()=>{
    const isMainBtnGameClicked = ref(false)

    return { isMainBtnGameClicked }
})

MyComponent.vue

//import { usePlayerStore } from '...'
const playerStore = usePlayerStore()        
playerStore.isMainBtnGameClicked = true

The 'isMainBtnGameClicked' variable in my store gets updated as expected.

In addition, I have discovered that I can also update variables directly from components by passing them by reference to the pinia store. This feature works seamlessly in my project.

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