fix(menu): return focus to root trigger when closed by mouse (#8348)

Previously we only restored focus to the trigger if the user opened the menu using a keyboard, however that means that focus can be lost when closing by clicking on the backdrop. These changes switch to also restoring focus when clicking away, but only if the trigger is a top-level trigger.

Fixes #8290.

Author: crisbeto

src/lib/menu/menu-trigger.ts

@@ -273,9 +273,10 @@ export class MatMenuTrigger implements AfterContentInit, OnDestroy {
   private _resetMenu(): void {
     this._setIsMenuOpen(false);
 
-    // Focus only needs to be reset to the host element if the menu was opened
-    // by the keyboard and manually shifted to the first menu item.
-    if (!this._openedByMouse) {
+    // We should reset focus if the user is navigating using a keyboard or
+    // if we have a top-level trigger which might cause focus to be lost
+    // when clicking on the backdrop.
+    if (!this._openedByMouse || !this.triggersSubmenu()) {
       this.focus();
     }
 

src/lib/menu/menu.spec.ts

@@ -104,6 +104,43 @@ describe('MatMenu', () => {
     expect(overlayContainerElement.textContent).toBe('');
   }));
 
+  it('should restore focus to the trigger when the menu was opened by keyboard', fakeAsync(() => {
+    const fixture = TestBed.createComponent(SimpleMenu);
+    fixture.detectChanges();
+
+    const triggerEl = fixture.componentInstance.triggerEl.nativeElement;
+
+    // A click without a mousedown before it is considered a keyboard open.
+    triggerEl.click();
+    fixture.detectChanges();
+
+    expect(overlayContainerElement.querySelector('.mat-menu-panel')).toBeTruthy();
+
+    fixture.componentInstance.trigger.closeMenu();
+    fixture.detectChanges();
+    tick(500);
+
+    expect(document.activeElement).toBe(triggerEl);
+  }));
+
+  it('should restore focus to the root trigger when the menu was opened by mouse', fakeAsync(() => {
+    const fixture = TestBed.createComponent(SimpleMenu);
+    fixture.detectChanges();
+
+    const triggerEl = fixture.componentInstance.triggerEl.nativeElement;
+    dispatchFakeEvent(triggerEl, 'mousedown');
+    triggerEl.click();
+    fixture.detectChanges();
+
+    expect(overlayContainerElement.querySelector('.mat-menu-panel')).toBeTruthy();
+
+    fixture.componentInstance.trigger.closeMenu();
+    fixture.detectChanges();
+    tick(500);
+
+    expect(document.activeElement).toBe(triggerEl);
+  }));
+
   it('should close the menu when pressing ESCAPE', fakeAsync(() => {
     const fixture = TestBed.createComponent(SimpleMenu);
     fixture.detectChanges();
@@ -1096,6 +1133,28 @@ describe('MatMenu', () => {
       expect(overlay.querySelectorAll('.mat-menu-panel').length).toBe(2, 'Expected two open menus');
     }));
 
+    it('should not re-focus a child menu trigger when hovering another trigger', fakeAsync(() => {
+      compileTestComponent();
+
+      dispatchFakeEvent(instance.rootTriggerEl.nativeElement, 'mousedown');
+      instance.rootTriggerEl.nativeElement.click();
+      fixture.detectChanges();
+
+      const items = Array.from(overlay.querySelectorAll('.mat-menu-panel [mat-menu-item]'));
+      const levelOneTrigger = overlay.querySelector('#level-one-trigger')!;
+
+      dispatchMouseEvent(levelOneTrigger, 'mouseenter');
+      fixture.detectChanges();
+      expect(overlay.querySelectorAll('.mat-menu-panel').length).toBe(2, 'Expected two open menus');
+
+      dispatchMouseEvent(items[items.indexOf(levelOneTrigger) + 1], 'mouseenter');
+      fixture.detectChanges();
+      tick(500);
+
+      expect(document.activeElement)
+          .not.toBe(levelOneTrigger, 'Expected focus not to be returned to the initial trigger.');
+    }));
+
   });
 
 });