fix(drawer): re-add openedStart and closedStart events (#7747)

* Re-adds the `openedStart` and `closedStart` events due to popular demand.
* Fixes wrong signature for the returned promise from toggle. The signature states that the resolved value is supposed to be a `MatDrawerToggleResult` while in practice it was `undefined`.

src/demo-app/drawer/drawer-demo.html

@@ -1,7 +1,7 @@
 <h2>Basic Use Case</h2>
 
 <mat-drawer-container class="demo-drawer-container">
-  <mat-drawer #start (open)="myinput.focus()" mode="side">
+  <mat-drawer #start (opened)="myinput.focus()" mode="side">
     Start Side Drawer
     <br>
     <button mat-button (click)="start.close()">Close</button>

src/lib/sidenav/drawer.spec.ts

@@ -28,43 +28,96 @@ describe('MatDrawer', () => {
   }));
 
   describe('methods', () => {
-    it('should be able to open and close', fakeAsync(() => {
-      let fixture = TestBed.createComponent(BasicTestApp);
+    it('should be able to open', fakeAsync(() => {
+      const fixture = TestBed.createComponent(BasicTestApp);
 
       fixture.detectChanges();
 
-      let testComponent: BasicTestApp = fixture.debugElement.componentInstance;
-      let drawer = fixture.debugElement.query(By.directive(MatDrawer));
-      let drawerBackdropElement = fixture.debugElement.query(By.css('.mat-drawer-backdrop'));
+      const testComponent: BasicTestApp = fixture.debugElement.componentInstance;
+      const drawer = fixture.debugElement.query(By.directive(MatDrawer));
+      const drawerBackdropElement = fixture.debugElement.query(By.css('.mat-drawer-backdrop'));
 
       drawerBackdropElement.nativeElement.style.transition = 'none';
       fixture.debugElement.query(By.css('.open')).nativeElement.click();
       fixture.detectChanges();
 
       expect(testComponent.openCount).toBe(0);
-      expect(testComponent.closeCount).toBe(0);
+      expect(testComponent.openStartCount).toBe(0);
 
       tick();
+      expect(testComponent.openStartCount).toBe(1);
       fixture.detectChanges();
 
       expect(testComponent.openCount).toBe(1);
-      expect(testComponent.closeCount).toBe(0);
+      expect(testComponent.openStartCount).toBe(1);
       expect(getComputedStyle(drawer.nativeElement).visibility).toBe('visible');
       expect(getComputedStyle(drawerBackdropElement.nativeElement).visibility).toBe('visible');
+    }));
+
+    it('should be able to close', fakeAsync(() => {
+      const fixture = TestBed.createComponent(BasicTestApp);
+
+      fixture.detectChanges();
+
+      const testComponent: BasicTestApp = fixture.debugElement.componentInstance;
+      const drawer = fixture.debugElement.query(By.directive(MatDrawer));
+      const drawerBackdropElement = fixture.debugElement.query(By.css('.mat-drawer-backdrop'));
+
+      drawerBackdropElement.nativeElement.style.transition = 'none';
+      fixture.debugElement.query(By.css('.open')).nativeElement.click();
+      fixture.detectChanges();
+      tick();
+      fixture.detectChanges();
 
       fixture.debugElement.query(By.css('.close')).nativeElement.click();
       fixture.detectChanges();
 
-      expect(testComponent.openCount).toBe(1);
       expect(testComponent.closeCount).toBe(0);
+      expect(testComponent.closeStartCount).toBe(0);
 
+      tick();
+      expect(testComponent.closeStartCount).toBe(1);
+      fixture.detectChanges();
+
+      expect(testComponent.closeCount).toBe(1);
+      expect(testComponent.closeStartCount).toBe(1);
+      expect(getComputedStyle(drawer.nativeElement).visibility).toBe('hidden');
+      expect(getComputedStyle(drawerBackdropElement.nativeElement).visibility).toBe('hidden');
+    }));
+
+    it('should resolve the open method promise with an object', fakeAsync(() => {
+      const fixture = TestBed.createComponent(BasicTestApp);
+      fixture.detectChanges();
+      const drawer = fixture.debugElement.query(By.directive(MatDrawer));
+
+      drawer.componentInstance.open().then(result => {
+        expect(result).toBeTruthy();
+        expect(result.type).toBe('open');
+        expect(result.animationFinished).toBe(true);
+      });
+      fixture.detectChanges();
+      tick();
+      fixture.detectChanges();
+    }));
+
+    it('should resolve the close method promise with an object', fakeAsync(() => {
+      const fixture = TestBed.createComponent(BasicTestApp);
+      fixture.detectChanges();
+      const drawer = fixture.debugElement.query(By.directive(MatDrawer));
+
+      drawer.componentInstance.open();
+      fixture.detectChanges();
       tick();
       fixture.detectChanges();
 
-      expect(testComponent.openCount).toBe(1);
-      expect(testComponent.closeCount).toBe(1);
-      expect(getComputedStyle(drawer.nativeElement).visibility).toBe('hidden');
-      expect(getComputedStyle(drawerBackdropElement.nativeElement).visibility).toBe('hidden');
+      drawer.componentInstance.close().then(result => {
+        expect(result).toBeTruthy();
+        expect(result.type).toBe('close');
+        expect(result.animationFinished).toBe(true);
+      });
+      fixture.detectChanges();
+      tick();
+      fixture.detectChanges();
     }));
 
     it('should be able to close while the open animation is running', fakeAsync(() => {
@@ -139,13 +192,16 @@ describe('MatDrawer', () => {
       tick();
 
       expect(testComponent.openCount).toBe(1, 'Expected one open event.');
+      expect(testComponent.openStartCount).toBe(1, 'Expected one open start event.');
       expect(testComponent.closeCount).toBe(0, 'Expected no close events.');
+      expect(testComponent.closeStartCount).toBe(0, 'Expected no close start events.');
 
       dispatchKeyboardEvent(drawer.nativeElement, 'keydown', ESCAPE);
       fixture.detectChanges();
       tick();
 
       expect(testComponent.closeCount).toBe(1, 'Expected one close event.');
+      expect(testComponent.closeStartCount).toBe(1, 'Expected one close start event.');
     }));
 
     it('should fire the open event when open on init', fakeAsync(() => {
@@ -172,6 +228,7 @@ describe('MatDrawer', () => {
       tick();
 
       expect(testComponent.closeCount).toBe(0);
+      expect(testComponent.closeStartCount).toBe(0);
     }));
 
     it('should not close by clicking on the backdrop when disableClose is set', fakeAsync(() => {
@@ -189,6 +246,7 @@ describe('MatDrawer', () => {
       tick();
 
       expect(testComponent.closeCount).toBe(0);
+      expect(testComponent.closeStartCount).toBe(0);
     }));
 
     it('should restore focus on close if focus is inside drawer', fakeAsync(() => {
@@ -490,7 +548,9 @@ class DrawerContainerTwoDrawerTestApp {
     <mat-drawer-container (backdropClick)="backdropClicked()">
       <mat-drawer #drawer position="start"
                  (opened)="open()"
-                 (closed)="close()">
+                 (openedStart)="openStart()"
+                 (closed)="close()"
+                 (closedStart)="closeStart()">
         <button #drawerButton>Content.</button>
       </mat-drawer>
       <button (click)="drawer.open()" class="open" #openButton></button>
@@ -498,9 +558,11 @@ class DrawerContainerTwoDrawerTestApp {
     </mat-drawer-container>`,
 })
 class BasicTestApp {
-  openCount: number = 0;
-  closeCount: number = 0;
-  backdropClickedCount: number = 0;
+  openCount = 0;
+  openStartCount = 0;
+  closeCount = 0;
+  closeStartCount = 0;
+  backdropClickedCount = 0;
 
   @ViewChild('drawerButton') drawerButton: ElementRef;
   @ViewChild('openButton') openButton: ElementRef;
@@ -510,10 +572,18 @@ class BasicTestApp {
     this.openCount++;
   }
 
+  openStart() {
+    this.openStartCount++;
+  }
+
   close() {
     this.closeCount++;
   }
 
+  closeStart() {
+    this.closeStartCount++;
+  }
+
   backdropClicked() {
     this.backdropClickedCount++;
   }

src/lib/sidenav/drawer.ts

@@ -193,21 +193,39 @@ export class MatDrawer implements AfterContentInit, OnDestroy {
     return this.openedChange.pipe(filter(o => o), map(() => {}));
   }
 
+  /** Event emitted when the drawer has started opening. */
+  @Output()
+  get openedStart(): Observable<void> {
+    return this._animationStarted.pipe(
+      filter(e => e.fromState !== e.toState && e.toState.indexOf('open') === 0),
+      map(() => {})
+    );
+  }
+
   /** Event emitted when the drawer has been closed. */
   @Output('closed')
   get _closedStream(): Observable<void> {
     return this.openedChange.pipe(filter(o => !o), map(() => {}));
   }
 
+  /** Event emitted when the drawer has started closing. */
+  @Output()
+  get closedStart(): Observable<void> {
+    return this._animationStarted.pipe(
+      filter(e => e.fromState !== e.toState && e.toState === 'void'),
+      map(() => {})
+    );
+  }
+
   /**
    * Event emitted when the drawer is fully opened.
-   * @deprecated Use `openedChange` instead.
+   * @deprecated Use `opened` instead.
    */
   @Output('open') onOpen = this._openedStream;
 
   /**
    * Event emitted when the drawer is fully closed.
-   * @deprecated Use `openedChange` instead.
+   * @deprecated Use `closed` instead.
    */
   @Output('close') onClose = this._closedStream;
 
@@ -327,8 +345,10 @@ export class MatDrawer implements AfterContentInit, OnDestroy {
 
     // TODO(crisbeto): This promise is here for backwards-compatibility.
     // It should be removed next time we do breaking changes in the drawer.
-    return new Promise(resolve => {
-      (isOpen ? this.onOpen : this.onClose).pipe(first()).subscribe(resolve);
+    return new Promise<any>(resolve => {
+      this.openedChange.pipe(first()).subscribe(open => {
+        resolve(new MatDrawerToggleResult(open ? 'open' : 'close', true));
+      });
     });
   }