Method preload

packages/router/test/router_preloader.spec.ts:298–309

(route: Route, fn: () => Observable<unknown>)

    const mockPreloaderFactory = (): PreloadingStrategy => {
      class DelayedPreLoad implements PreloadingStrategy {
        preload(route: Route, fn: () => Observable<unknown>): Observable<unknown> {
          const routeName = route.loadChildren
            ? (route.loadChildren as jasmine.Spy).and.identity
            : 'noChildren';
          return delayLoadObserver$.pipe(
            filter((unpauseList) => unpauseList.indexOf(routeName) !== -1),
            take(1),
            switchMap(() => {
              return fn().pipe(catchError(() => of(null)));
            }),
          );
        }
      }
      return new DelayedPreLoad();
    };