sf-lwc-jest-testing

Use createElement from lwc to instantiate the component, append it to document.body, then assert against element.shadowRoot.querySelector results. Install @salesforce/sfdx-lwc-jest, which configures Jest for the DX workspace and ships stubs for all lightning base components.

Declare jest.mock with the full @salesforce/apex/Class.method path, a factory returning { default: jest.fn() }, and the { virtual: true } option since the path is synthetic. For @wire usage, return createApexTestWireAdapter(jest.fn()) and emit data through the adapter.

The most common cause is asserting before the rerender microtask completes; add await Promise.resolve() after setting properties or emitting wire data. Other causes are the wire config resolving to undefined so the adapter never fires, or missing DOM cleanup leaking state between tests.

No, Jest runs entirely offline with no org, authentication, or network access. All server interaction is simulated through wire test adapters and mocked Apex functions, so org-dependent behavior must be verified separately with Apex tests or post-deploy checks.

Map lightning/navigation to a hand-written mock in moduleNameMapper that exposes a NavigationMixin with jest.fn() spies for Navigate and GenerateUrl. Then assert the captured pageReference type, attributes, and actionName after clicking the element that triggers navigation.

Assert rendered text, element counts, branch selection for loading/data/empty/error states, event names with detail payloads, and Apex call arguments. Do not assert private fields, internal method calls, base component stub internals, or snapshots that are regenerated every sprint.