/**
 * Replaces `react-helmet-async`'s `Helmet` and `HelmetProvider` with no-op
 * components so head-mutating components rendered under test do not touch
 * the jsdom document.
 *
 * Opt-in: the mock is registered via `vi.doMock` so it is
 * NOT hoisted and only takes effect once `setupHelmetMock()` is called from
 * a test setup file. Tests that need the real `react-helmet-async` (or
 * their own mock) are unaffected unless they explicitly call this.
 *
 * See more details here: https://www.npmjs.com/package/react-helmet-async
 *
 * @example
 * import { setupHelmetMock } from '@trackunit/react-vite-test-setup';
 * setupHelmetMock();
 */
export declare const setupHelmetMock: () => void;