fix(drawer): unable to toggle while drawer is animating

Fixes not being able to toggle a drawer while it is mid-animation.

Fixes angular#6376.

Author: crisbeto

src/lib/sidenav/drawer.spec.ts

@@ -45,7 +45,6 @@ describe('MatDrawer', () => {
       tick();
       fixture.detectChanges();
 
-      expect(drawer.componentInstance._isAnimating).toBe(false);
       expect(testComponent.openCount).toBe(1);
       expect(testComponent.closeCount).toBe(0);
       expect(getComputedStyle(drawer.nativeElement).visibility).toBe('visible');
@@ -66,6 +65,27 @@ describe('MatDrawer', () => {
       expect(getComputedStyle(drawerBackdropElement.nativeElement).visibility).toBe('hidden');
     }));
 
+    it('should be able to close while the open animation is running', fakeAsync(() => {
+      const fixture = TestBed.createComponent(BasicTestApp);
+      fixture.detectChanges();
+
+      const testComponent: BasicTestApp = fixture.debugElement.componentInstance;
+      fixture.debugElement.query(By.css('.open')).nativeElement.click();
+      fixture.detectChanges();
+
+      expect(testComponent.openCount).toBe(0);
+      expect(testComponent.closeCount).toBe(0);
+
+      fixture.debugElement.query(By.css('.close')).nativeElement.click();
+      fixture.detectChanges();
+
+      tick();
+      fixture.detectChanges();
+
+      expect(testComponent.openCount).toBe(1);
+      expect(testComponent.closeCount).toBe(1);
+    }));
+
     it('does not throw when created without a drawer', fakeAsync(() => {
       expect(() => {
         let fixture = TestBed.createComponent(BasicTestApp);

src/lib/sidenav/drawer.ts

@@ -180,19 +180,9 @@ export class MatDrawer implements AfterContentInit, OnDestroy {
   /** Emits whenever the drawer has started animating. */
   _animationStarted = new EventEmitter<void>();
 
-  /** Whether the drawer is animating. Used to prevent overlapping animations. */
-  _isAnimating = false;
-
   /** Current state of the sidenav animation. */
   _animationState: 'open-instant' | 'open' | 'void' = 'void';
 
-  /**
-   * Promise that resolves when the open/close animation completes. It is here for backwards
-   * compatibility and should be removed next time we do drawer breaking changes.
-   * @deprecated
-   */
-  private _currentTogglePromise: Promise<MatDrawerToggleResult> | null;
-
   /** Event emitted when the drawer is fully opened. */
   @Output('open') onOpen = new EventEmitter<MatDrawerToggleResult | void>();
 
@@ -287,27 +277,23 @@ export class MatDrawer implements AfterContentInit, OnDestroy {
    * @param isOpen Whether the drawer should be open.
    */
   toggle(isOpen: boolean = !this.opened): Promise<MatDrawerToggleResult> {
-    if (!this._isAnimating) {
-      this._opened = isOpen;
+    this._opened = isOpen;
 
-      if (isOpen) {
-        this._animationState = this._enableAnimations ? 'open' : 'open-instant';
-      } else {
-        this._animationState = 'void';
-      }
-
-      this._currentTogglePromise = new Promise(resolve => {
-        first.call(isOpen ? this.onOpen : this.onClose).subscribe(resolve);
-      });
+    if (isOpen) {
+      this._animationState = this._enableAnimations ? 'open' : 'open-instant';
+    } else {
+      this._animationState = 'void';
+    }
 
-      if (this._focusTrap) {
-        this._focusTrap.enabled = this.isFocusTrapEnabled;
-      }
+    if (this._focusTrap) {
+      this._focusTrap.enabled = this.isFocusTrapEnabled;
     }
 
     // TODO(crisbeto): This promise is here for backwards-compatibility.
     // It should be removed next time we do breaking changes in the drawer.
-    return this._currentTogglePromise!;
+    return new Promise(resolve => {
+      first.call(isOpen ? this.onOpen : this.onClose).subscribe(resolve);
+    });
   }
 
   /**
@@ -322,7 +308,6 @@ export class MatDrawer implements AfterContentInit, OnDestroy {
   }
 
   _onAnimationStart() {
-    this._isAnimating = true;
     this._animationStarted.emit();
   }
 
@@ -334,14 +319,6 @@ export class MatDrawer implements AfterContentInit, OnDestroy {
     } else if (toState === 'void' && fromState === 'open') {
       this.onClose.emit(new MatDrawerToggleResult('close', true));
     }
-
-    // Note: as of Angular 4.3, the animations module seems to fire the `start` callback before
-    // the end if animations are disabled. Make this call async to ensure that it still fires
-    // at the appropriate time.
-    Promise.resolve().then(() => {
-      this._isAnimating = false;
-      this._currentTogglePromise = null;
-    });
   }
 
   get _width() {