LWC Testing Utils

A JavaScript library with helpful functionality for testing Salesforce Lightning Web Components (LWC).

Usage

The two main utilities in this library are the ShadowDomParser and the FormChanger.

Shadow Dom Parser

The ShadowDomParser allows us to parse the lwc shadow dom for certain elements and components:

<!-- hello/hello.html -->
<template>
    <div class="message">Hello World!</div>
    <c-user-profile></c-user-profile>
</template>

 <!-- userProfile/userProfile.html -->
<template>
    <div class="userName">
        You are signed in as {user.Username}.
    </div>
    <lightning-input type="text" label="Change Username" onchange={updateUsername}></lightning-input>
    <button onclick={changeUsername}>Update</button>
    <ul class="changes">
        <template for:each={usernameChanges} for:item="change">
            <li key={change.id} class="change">
                <a href={change.url} class="change-link">
                    {change.datetime}
                </a>
            </li>
        </template>
    </ul>
</template>

// parser.example.js
import { createElement } from "lwc";
import Hello from "c/hello";
import { ShadowDomParser } from "@purelightpower/lwc-testing-utils";

let element = createElement("c-hello", {
    is: Hello
});

let parser = new ShadowDomParser(element);

// Allows us to use it like a query selector for the top level component
let messageElement = parser.findOne(".message");

// Also allows us to use it as a query selector for elements nested in child components.
let userNameElement = parser.findOne(".userName");

// Find many elements
let changes = parser.findAll("ul.changes li.change");

// Select a lightning input
let lightningInputElement = parser.findLightningInputByLabel("Change Username");

Form Changer

The form changer class allows us to change the fields in a custom lwc form.

<!-- form/form.html -->
<template>
    <div class="slds-form">
        <div class="slds-form-element">
            <lightning-input
                type="text"
                label="First Name"
            ></lightning-input>
        </div>
        <div class="slds-form-element">
            <lightning-input
                type="text"
                label="Last Name"
            ></lightning-input>
        </div>
        <div class="slds-form-element">
            <lightning-input
                type="text"
                label="Nickname"
            ></lightning-input>
        </div>
        <div class="slds-form-element">
            <button onclick={submit}>
                Submit
            </button>
        </div>
    </div>
</template>

// changer.example.js
import { createElement } from "lwc";
import Form from "c/form";
import { FormChanger } from "@purelightpower/lwc-testing-utils";

let element = createElement("c-form", {
    is: Form
});

let changer = FormChanger.fromElement(element);

// Change the value of a lightning input field
changer.changeLightningInput("First Name", "John")
    .then(() => (
        changer.changeLightningInput("Last Name", "Doe")
    ))
    .then(() => (
        changer.changeLightningInput("Nickname", "Johnny")
    ));

Tools

• Jest - A JavaScript testing framework.
• LWC - Lightning web components are custom elements built using HTML and modern JavaScript.

Contributors

• Morgan Billingsley - mbillingsley@purelightpower.com