fix(sidenav): throw error when sidenav has 2 sidenavs on the same side at the same time (#3369)

src/demo-app/sidenav/sidenav-demo.html

@@ -51,10 +51,13 @@
 <h2>Dynamic Alignment Sidenav</h2>
 
 <md-sidenav-container class="demo-sidenav-container">
-  <md-sidenav #dynamicAlignSidenav mode="push" [align]="side">Drawer</md-sidenav>
+  <md-sidenav #dynamicAlignSidenav1 mode="side" [align]="invert ? 'end' : 'start'">Start</md-sidenav>
+  <md-sidenav #dynamicAlignSidenav2 mode="side" [align]="invert ? 'start' : 'end'">End</md-sidenav>
 
   <div class="demo-sidenav-content">
-    <button (click)="dynamicAlignSidenav.toggle()">Toggle sidenav</button>
-    <button (click)="side = (side == 'start') ? 'end' : 'start'">Change sides</button>
+    <button (click)="dynamicAlignSidenav1.toggle(); dynamicAlignSidenav2.toggle()">
+      Toggle sidenavs
+    </button>
+    <button (click)="invert = !invert">Change sides</button>
   </div>
 </md-sidenav-container>

src/demo-app/sidenav/sidenav-demo.ts

@@ -9,5 +9,5 @@ import {Component, ViewEncapsulation} from '@angular/core';
   encapsulation: ViewEncapsulation.None,
 })
 export class SidenavDemo {
-  side = 'start';
+  invert = false;
 }

src/lib/sidenav/sidenav.scss

@@ -135,7 +135,3 @@
     }
   }
 }
-
-.mat-sidenav-invalid {
-  display: none;
-}

src/lib/sidenav/sidenav.spec.ts

@@ -373,23 +373,25 @@ describe('MdSidenav', () => {
           .toBe(false, 'Expected sidenav not to have a native align attribute.');
     });
 
-    it('should mark sidenavs invalid when multiple have same align', () => {
+    it('should throw when multiple sidenavs have the same align', () => {
       const fixture = TestBed.createComponent(SidenavDynamicAlign);
       fixture.detectChanges();
 
       const testComponent: SidenavDynamicAlign = fixture.debugElement.componentInstance;
-      const sidenavEl = fixture.debugElement.query(By.css('md-sidenav')).nativeElement;
-      expect(sidenavEl.classList).not.toContain('mat-sidenav-invalid');
-
       testComponent.sidenav1Align = 'end';
+
+      expect(() => fixture.detectChanges()).toThrow();
+    });
+
+    it('should not throw when sidenavs swap sides', () => {
+      const fixture = TestBed.createComponent(SidenavDynamicAlign);
       fixture.detectChanges();
 
-      expect(sidenavEl.classList).toContain('mat-sidenav-invalid');
-
+      const testComponent: SidenavDynamicAlign = fixture.debugElement.componentInstance;
+      testComponent.sidenav1Align = 'end';
       testComponent.sidenav2Align = 'start';
-      fixture.detectChanges();
 
-      expect(sidenavEl.classList).not.toContain('mat-sidenav-invalid');
+      expect(() => fixture.detectChanges()).not.toThrow();
     });
   });
 

src/lib/sidenav/sidenav.ts

@@ -65,7 +65,6 @@ export class MdSidenavToggleResult {
     '[class.mat-sidenav-over]': '_modeOver',
     '[class.mat-sidenav-push]': '_modePush',
     '[class.mat-sidenav-side]': '_modeSide',
-    '[class.mat-sidenav-invalid]': '!valid',
     'tabIndex': '-1'
   },
   changeDetection: ChangeDetectionStrategy.OnPush,
@@ -77,19 +76,6 @@ export class MdSidenav implements AfterContentInit, OnDestroy {
   /** Alignment of the sidenav (direction neutral); whether 'start' or 'end'. */
   private _align: 'start' | 'end' = 'start';
 
-  /** Whether this md-sidenav is part of a valid md-sidenav-container configuration. */
-  get valid() { return this._valid; }
-  set valid(value) {
-    value = coerceBooleanProperty(value);
-    // When the drawers are not in a valid configuration we close them all until they are in a valid
-    // configuration again.
-    if (!value) {
-      this.close();
-    }
-    this._valid = value;
-  }
-  private _valid = true;
-
   /** Direction which the sidenav is aligned in. */
   @Input()
   get align() { return this._align; }
@@ -221,10 +207,6 @@ export class MdSidenav implements AfterContentInit, OnDestroy {
    * @returns Resolves with the result of whether the sidenav was opened or closed.
    */
   toggle(isOpen: boolean = !this.opened): Promise<MdSidenavToggleResult> {
-    if (!this.valid) {
-      return Promise.resolve(new MdSidenavToggleResult(isOpen ? 'open' : 'close', true));
-    }
-
     // Shortcut it if we're already opened.
     if (isOpen === this.opened) {
       return this._toggleAnimationPromise ||
@@ -410,8 +392,13 @@ export class MdSidenavContainer implements AfterContentInit {
    * changes.
    */
   private _watchSidenavAlign(sidenav: MdSidenav): void {
-    if (!sidenav) { return; }
-    sidenav.onAlignChanged.subscribe(() => this._validateDrawers());
+    if (!sidenav) {
+      return;
+    }
+    // NOTE: We need to wait for the microtask queue to be empty before validating,
+    // since both drawers may be swapping sides at the same time.
+    sidenav.onAlignChanged.subscribe(() =>
+        this._ngZone.onMicrotaskEmpty.first().subscribe(() => this._validateDrawers()));
   }
 
   /** Toggles the 'mat-sidenav-opened' class on the main 'md-sidenav-container' element. */
@@ -419,16 +406,6 @@ export class MdSidenavContainer implements AfterContentInit {
     this._renderer.setElementClass(this._element.nativeElement, 'mat-sidenav-opened', bool);
   }
 
-  /** Sets the valid state of the drawers. */
-  private _setDrawersValid(valid: boolean) {
-    this._sidenavs.forEach((sidenav) => {
-      sidenav.valid = valid;
-    });
-    if (!valid) {
-      this._start = this._end = this._left = this._right = null;
-    }
-  }
-
   /** Validate the state of the sidenav children components. */
   private _validateDrawers() {
     this._start = this._end = null;
@@ -439,14 +416,12 @@ export class MdSidenavContainer implements AfterContentInit {
     for (let sidenav of this._sidenavs.toArray()) {
       if (sidenav.align == 'end') {
         if (this._end != null) {
-          this._setDrawersValid(false);
-          return;
+          throw new MdDuplicatedSidenavError('end');
         }
         this._end = sidenav;
       } else {
         if (this._start != null) {
-          this._setDrawersValid(false);
-          return;
+          throw new MdDuplicatedSidenavError('start');
         }
         this._start = sidenav;
       }
@@ -462,8 +437,6 @@ export class MdSidenavContainer implements AfterContentInit {
       this._left = this._end;
       this._right = this._start;
     }
-
-    this._setDrawersValid(true);
   }
 
   _onBackdropClicked() {