sampleForm.html ===================== <template> <lightning-input type="text" label="FirstName" class="fname"></lightning-input> <lightning-input type="text" label="LastName" class="lname"></lightning-input> <lightning-button label="Disable" variant="brand" onclick={handleClick}></lightning-button> </template> sampleForm.js ==================== import { LightningElement,track } from 'lwc'; export default class SampleForm extends LightningElement { handleClick(){ this.template.querySelectorAll('lightning-input').forEach(item=>{ item.disabled=true; }) } } sampleForm.test.js ======================== import {createElement} from 'lwc'; import SampleForm from 'c/sampleForm'; describe('c-sample-form',()=>{ beforeEach(()=>{ const element=createElement('c-sample-form',{ is:SampleForm }) document.body.appendChild(element); }) test('display input fields in disabled format',()=>{ const element=document.querySelector('c-sample-form'); const inputButton=element.shadowRoot.querySelector('lightning-button'); inputButton.dispatchEvent(new CustomEvent('click')); return Promise.resolve().then(()=>{ const inputVal=element.shadowRoot.querySelectorAll('lightning-input').forEach(item=>{ expect(item.disabled).toBeTruthy(); }); }) }) })