Simplify test about maintaining selected tab

Author: devversion

src/lib/tabs/tab-group.spec.ts

@@ -388,29 +388,28 @@ describe('MatTabGroup', () => {
         {label: 'Another new tab', content: 'with newer content'}
       );
 
-      // Select the second-to-last tab.
-      fixture.componentInstance.selectedIndex = 3;
+      // Select the second tab.
+      fixture.componentInstance.selectedIndex = 1;
       fixture.detectChanges();
 
       const component: MatTabGroup =
           fixture.debugElement.query(By.css('mat-tab-group')).componentInstance;
 
-      // Remove a tab right before the selected one.
-      fixture.componentInstance.tabs.splice(2, 1);
+      // Remove the first tab that is right before the selected one.
+      fixture.componentInstance.tabs.splice(0, 1);
       fixture.detectChanges();
 
-      // Since the third tab has been removed and the fourth was selected before, the selected
-      // tab moved one position to the right. Meaning that the tab is now at index: *2*.
-      expect(component.selectedIndex).toBe(2);
-      expect(component._tabs.toArray()[2].isActive).toBe(true);
+      // Since the first tab has been removed and the second one was selected before, the selected
+      // tab moved one position to the right. Meaning that the tab is now the first tab.
+      expect(component.selectedIndex).toBe(0);
+      expect(component._tabs.toArray()[0].isActive).toBe(true);
     });
 
     it('should be able to select a new tab after creation', () => {
       fixture.detectChanges();
       const component: MatTabGroup =
         fixture.debugElement.query(By.css('mat-tab-group')).componentInstance;
 
-      // Add a new tab at the beginning.
       fixture.componentInstance.tabs.push({label: 'Last tab', content: 'at the end'});
       fixture.componentInstance.selectedIndex = 3;