Tips for testing "defineAsyncComponent" in Vue 3:

Question

Tips for testing "defineAsyncComponent" in Vue 3:

Suppose I need to unit test this utility function. I am utilizing Vue 3, however, this code resides in a "regular" JavaScript file rather than an SFC.

How can I go about doing that?

function getDynamicComponent() {
  if (...)  {
    return defineAsyncComponent(() => import('../path/to/component-A.vue'))
  } else {
    return defineAsyncComponent(() => import('../path/to/component-B.vue'))
  }
}

In scenarios like this, my approach is to mock the implementation of functions and verify .toHaveBeenCalledWith(...). But since I cannot do that with import, right?

P.S. Any insights into Jest or Vitest syntax would be greatly appreciated

javascript vue.js unit-testing jestjs vuejs3

Answer 1

Answer №1

If you want to test a specific function using jest, you can mock it like this:

let defineAsyncComponent = jest.fn()

let vueMock = {
    defineAsyncComponent
}

jest.mock('vue', () => {
    return vueMock;
})

import { defineAsyncComponent } from 'vue';

console.log(defineAsyncComponent._isMockFunction) // true

To ensure that defineAsyncComponent was called during your test, you can do the following:

expect(defineAsyncComponent).toHaveBeenCalled()

It's important to note that testing with toHaveBeenCalledWith may be challenging as it uses toEqual and could lead to failed tests.

One approach is to define an implementation for the defineAsyncComponent function in order to test the parameter:

let defineAsyncComponent = jest.fn().mockImplementation((fn) => {
    expect(typeof fn).toBe('function')
})

You could also verify the returned promise value by calling the function, but keep in mind that at this point you are essentially testing the import() function itself rather than adding value to your test:

let defineAsyncComponent = jest.fn().mockImplementation((fn) => {
    expect(typeof fn).toBe('function')
    expect(typeof fn().then).toBe('function')
})

Answer 2

If you want to test a specific function using jest, you can mock it like this:

let defineAsyncComponent = jest.fn()

let vueMock = {
    defineAsyncComponent
}

jest.mock('vue', () => {
    return vueMock;
})

import { defineAsyncComponent } from 'vue';

console.log(defineAsyncComponent._isMockFunction) // true

To ensure that defineAsyncComponent was called during your test, you can do the following:

expect(defineAsyncComponent).toHaveBeenCalled()

It's important to note that testing with toHaveBeenCalledWith may be challenging as it uses toEqual and could lead to failed tests.

One approach is to define an implementation for the defineAsyncComponent function in order to test the parameter:

let defineAsyncComponent = jest.fn().mockImplementation((fn) => {
    expect(typeof fn).toBe('function')
})

You could also verify the returned promise value by calling the function, but keep in mind that at this point you are essentially testing the import() function itself rather than adding value to your test:

let defineAsyncComponent = jest.fn().mockImplementation((fn) => {
    expect(typeof fn).toBe('function')
    expect(typeof fn().then).toBe('function')
})

Tips for testing "defineAsyncComponent" in Vue 3:

Answer №1

Similar questions

The issue with ngFileUpload causing empty file posts on Safari

Merge JSON objects while retaining duplicate keys

Failure to persist Vuex data using createPersistedState

I encounter an error message stating "Cannot read property 'push' of undefined" when trying to add an item to a property within an interface

Creating a JavaScript array filled with database data using PHP

Bidirectional data binding with VDataTable in Vue using JSX syntax

PHP is capable of showing echo statements from the function, however it does not directly showcase database information

Exploring NextJS with Typescript

Iterating over images and displaying them in Laravel's blade templating engine, updating outdated Angular code

Why is the server displaying a blank white page following the import of Material UI icons/module?

Does the AngularJS Controller disappear when the DOM element is "deleted"?

Show the textbox automatically when the checkbox is selected, otherwise keep the textbox hidden

Next JS Event Listener Failing to Detect Scroll Events

Executing a Python script within a Django project by clicking on an HTML button

How to implement mouse hover functionality in C# using Selenium?

What are the steps to resolve the issue "Error: no valid exports main found" specifically on a Windows 7 operating system?

Immersive jQuery slideshow embellished with an interactive counter, captivating thumbnails, dynamic progress bar,

AngularJS factory with local storage functionality

What is the proper usage of a jwt token?

Altering the color of a Fabulous Icon in real-time