Testing Wire Adapters and Apex-Dependent Components

A Jest test (Lesson 1) runs with no real Salesforce org connection — an actual @wire(getRecord, ...) or Apex call genuinely cannot execute in this environment. A mock stands in for the real thing, simulating the response so the component's rendering logic can still be tested against realistic data.

import { createElement } from 'lwc';
import { getRecord } from 'lightning/uiRecordApi';
import AccountSummary from 'c/accountSummary';

jest.mock('lightning/uiRecordApi', () => ({
    getRecord: jest.fn(),
}));

it('renders the account name once wire data emits', async () => {
    const element = createElement('c-account-summary', { is: AccountSummary });
    document.body.appendChild(element);

    getRecord.emit({ fields: { Name: { value: 'Acme Corp' } } });
    await Promise.resolve();

    const name = element.shadowRoot.querySelector('.account-name');
    expect(name.textContent).toBe('Acme Corp');
});

jest.mock(...) replaces the real lightning/uiRecordApi module with a test double. getRecord.emit(...) (from the @salesforce/sfdx-lwc-jest wire-testing utilities) pushes fake data through the mocked adapter, triggering the component's @wire-based rendering (Module 6) exactly as real data arriving would.

import searchAccounts from '@salesforce/apex/AccountSearchController.search';

jest.mock(
    '@salesforce/apex/AccountSearchController.search',
    () => ({ default: jest.fn() }),
    { virtual: true }
);

it('shows an error message when the search fails', async () => {
    searchAccounts.mockRejectedValue(new Error('Search failed'));

    const element = createElement('c-account-search', { is: AccountSearch });
    document.body.appendChild(element);

    element.shadowRoot.querySelector('lightning-button').click();
    await Promise.resolve();

    const error = element.shadowRoot.querySelector('.error-message');
    expect(error).not.toBeNull();
});

mockResolvedValue/mockRejectedValue control what the mocked Apex call returns, letting both the success path and the error-handling path (Module 7's try/catch) be tested deliberately, including failure scenarios that would be awkward to force in a real org.