The `HttpClient` tests in `client_spec.ts` were failing intermittently in Node/Domino environment because `MockPlatformLocation` defaults to `http://_empty_/`. This valid URL satisfied the URL parser in `xsrfInterceptorFn`, causing it to proceed to cookie extraction which throws `NotYetImplemented` in Domino.
To fix this:
1. Disabled XSRF protection in `client_spec.ts` using `withNoXsrfProtection()`, as these tests are not for XSRF.
2. Provided `ɵprovideFakePlatformNavigation` to remove state leakage effects and ensure consistency.