fix(aio): use the current version in the version picker

Previously we hardcoded the current version into the navigation items.
Now only previous versions are included there. The current version is
computed from the currentVersion info.

Closes #16909

aio/content/navigation.json

@@ -484,7 +484,6 @@
   ],
 
   "docVersions": [
-    { "title": "v4.0.0", "url": null },
-    { "title": "v2",     "url": "https://v2.angular.io" }
+    { "title": "v2", "url": "https://v2.angular.io" }
   ]
 }

aio/src/app/app.component.spec.ts

@@ -210,14 +210,14 @@ describe('AppComponent', () => {
 
     it('should pick first (current) version by default', () => {
       const versionSelector = sidenav.querySelector('select');
-      expect(versionSelector.value).toEqual(TestHttp.docVersions[0].title);
+      expect(versionSelector.value).toEqual(component.versionInfo.raw);
       expect(versionSelector.selectedIndex).toEqual(0);
     });
 
     // Older docs versions have an href
     it('should navigate when change to a version with an href', () => {
       component.onDocVersionChange(1);
-      expect(locationService.go).toHaveBeenCalledWith(TestHttp.docVersions[1].url);
+      expect(locationService.go).toHaveBeenCalledWith(TestHttp.docVersions[0].url);
     });
 
     // The current docs version should not have an href
@@ -612,7 +612,6 @@ class TestHttp {
   static versionFull = '4.0.0-local+sha.73808dd';
 
   static docVersions: NavigationNode[] = [
-    { title: 'v4.0.0' },
     { title: 'v2', url: 'https://v2.angular.io' }
   ];
 

aio/src/app/app.component.ts

@@ -13,6 +13,8 @@ import { SearchBoxComponent } from 'app/search/search-box/search-box.component';
 import { SearchService } from 'app/search/search.service';
 import { SwUpdateNotificationsService } from 'app/sw-updates/sw-update-notifications.service';
 
+import { combineLatest } from 'rxjs/observable/combineLatest';
+
 const sideNavView = 'SideNav';
 
 @Component({
@@ -139,13 +141,20 @@ export class AppComponent implements OnInit {
       this.sideNavToggle(this.isSideBySide ? openSideNav : false);
     });
 
+    // Compute the version picker list from the current version and the versions in the navigation map
+    combineLatest(
+      this.navigationService.versionInfo.map(versionInfo => ({ title: versionInfo.raw, url: null })),
+      this.navigationService.navigationViews.map(views => views['docVersions']),
+      (currentVersion, otherVersions) => [currentVersion, ...otherVersions])
+      .subscribe(versions => {
+        this.docVersions = versions;
+        this.currentDocVersion = this.docVersions[0];
+      });
+
     this.navigationService.navigationViews.subscribe(views => {
-      this.docVersions  = views['docVersions']  || [];
       this.footerNodes  = views['Footer']  || [];
       this.sideNavNodes = views['SideNav'] || [];
       this.topMenuNodes = views['TopBar']  || [];
-
-      this.currentDocVersion = this.docVersions[0];
     });
 
     this.navigationService.versionInfo.subscribe( vi => this.versionInfo = vi );