fix(router): guards restor an incorrect url when used with skipLocationChange

Closes #12825

modules/@angular/router/src/router.ts

@@ -299,6 +299,7 @@ type NavigationParams = {
 export class Router {
   private currentUrlTree: UrlTree;
   private rawUrlTree: UrlTree;
+  private currentUrlTreeStoredInLocation: UrlTree;
 
   private navigations: BehaviorSubject<NavigationParams> =
       new BehaviorSubject<NavigationParams>(null);
@@ -716,6 +717,7 @@ export class Router {
       let navigationIsSuccessful: boolean;
       const storedState = this.currentRouterState;
       const storedUrl = this.currentUrlTree;
+      const storedUrlInLocation = this.currentUrlTreeStoredInLocation;
 
       routerState$
           .forEach(({appliedUrl, state, shouldActivate}: any) => {
@@ -726,6 +728,8 @@ export class Router {
 
             this.currentUrlTree = appliedUrl;
             this.rawUrlTree = this.urlHandlingStrategy.merge(this.currentUrlTree, rawUrl);
+            this.currentUrlTreeStoredInLocation =
+                shouldPreventPushState ? this.currentUrlTreeStoredInLocation : this.rawUrlTree;
 
             this.currentRouterState = state;
 
@@ -774,14 +778,13 @@ export class Router {
                 this.currentRouterState = storedState;
                 this.currentUrlTree = storedUrl;
                 this.rawUrlTree = this.urlHandlingStrategy.merge(this.currentUrlTree, rawUrl);
-                this.location.replaceState(this.serializeUrl(this.rawUrlTree));
+                this.location.replaceState(this.serializeUrl(storedUrlInLocation));
               });
     });
   }
 
   private resetUrlToCurrentUrlTree(): void {
-    const path = this.urlSerializer.serialize(this.rawUrlTree);
-    this.location.replaceState(path);
+    this.location.replaceState(this.urlSerializer.serialize(this.currentUrlTreeStoredInLocation));
   }
 }
 

modules/@angular/router/test/integration.spec.ts

@@ -1532,6 +1532,27 @@ describe('Integration', () => {
              expect(location.path()).toEqual('/main/component1');
            })));
 
+        it('should respect skipLocationChange when guards cancel navigations',
+           fakeAsync(inject([Router, Location], (router: Router, location: Location) => {
+             const fixture = createRoot(router, RootCmp);
+
+             router.resetConfig([
+               {path: 'component1', component: SimpleCmp},
+               {path: 'component2', component: SimpleCmp, canDeactivate: ['alwaysFalse']}
+             ]);
+
+             router.navigateByUrl('/component1');  // initial state
+             advance(fixture);
+
+             router.navigateByUrl('/component2', {skipLocationChange: true});
+             advance(fixture);
+             expect(location.path()).toEqual('/component1');
+
+             location.back();
+             advance(fixture);
+
+             expect(location.path()).toEqual('/component1');
+           })));
       });
 
       describe('should work when given a class', () => {