fix issue where invalidateRootCache didn't happen when the page first loaded

Author: artlowel

src/app/core/server-check/server-check.guard.spec.ts

@@ -63,16 +63,18 @@ describe('ServerCheckGuard', () => {
   });
 
   describe(`listenForRouteChanges`, () => {
-    it(`should invalidate the root cache on every NavigationStart event`, () => {
+    it(`should invalidate the root cache when the method is first called, and then on every NavigationStart event`, () => {
         testScheduler.run(() => {
           guard.listenForRouteChanges();
+          expect(rootDataServiceStub.invalidateRootCache).toHaveBeenCalledTimes(1);
+
           eventSubject.next(new NavigationStart(1,''));
           eventSubject.next(new NavigationEnd(1,'', ''));
           eventSubject.next(new NavigationStart(2,''));
           eventSubject.next(new NavigationEnd(2,'', ''));
           eventSubject.next(new NavigationStart(3,''));
         });
-        expect(rootDataServiceStub.invalidateRootCache).toHaveBeenCalledTimes(3);
+        expect(rootDataServiceStub.invalidateRootCache).toHaveBeenCalledTimes(4);
     });
   });
 });

src/app/core/server-check/server-check.guard.ts

@@ -52,6 +52,10 @@ export class ServerCheckGuard implements CanActivateChild {
    * operation, the cached version is used.
    */
   listenForRouteChanges(): void {
+    // we'll always be too late for the first NavigationStart event with the router subscribe below,
+    // so this statement is for the very first route operation
+    this.rootDataService.invalidateRootCache();
+
     this.router.events.pipe(
       filter(event => event instanceof NavigationStart),
     ).subscribe(() => {