fix(material-experimental/mdc-progress-bar): changed after checked error on animation end event with noop animations (#18508)

Along the same lines as #18441. If the `animationEnd` of a progress bar is used to update something in the view of an app that has disabled animations, a "changed after checked" error will be thrown because of the timing at which we dispatch the event. These changes work around the issue by not having separate logic for when the animations are enabled or disabled.

Author: crisbeto

src/material-experimental/mdc-progress-bar/progress-bar.scss

@@ -7,6 +7,14 @@
   // Explicitly set to `block` since the browser defaults custom elements to `inline`.
   display: block;
 
+  &._mat-animation-noopable {
+    .mdc-linear-progress__primary-bar {
+      // There's a `transitionend` event that depends on this element. Add a very short
+      // transition when animations are disabled so that the event can still fire.
+      transition: transform 1ms;
+    }
+  }
+
   &:not(._mat-animation-noopable) {
     @include mdc-linear-progress-core-styles($query: animation);
   }

src/material-experimental/mdc-progress-bar/progress-bar.spec.ts

@@ -1,8 +1,7 @@
-import {TestBed, async, ComponentFixture} from '@angular/core/testing';
+import {TestBed, ComponentFixture} from '@angular/core/testing';
 import {Component, DebugElement, Type} from '@angular/core';
 import {By} from '@angular/platform-browser';
 import {dispatchFakeEvent} from '@angular/cdk/testing/private';
-import {NoopAnimationsModule} from '@angular/platform-browser/animations';
 import {MatProgressBarModule} from './index';
 import {MatProgressBar} from './progress-bar';
 
@@ -213,33 +212,6 @@ describe('MDC-based MatProgressBar', () => {
     });
   });
 
-  describe('With NoopAnimations', () => {
-    let progressComponent: MatProgressBar;
-    let primaryValueBar: DebugElement;
-    let fixture: ComponentFixture<BasicProgressBar>;
-
-    beforeEach(async(() => {
-      fixture = createComponent(BasicProgressBar, [MatProgressBarModule, NoopAnimationsModule]);
-      const progressElement = fixture.debugElement.query(By.css('mat-progress-bar'))!;
-      progressComponent = progressElement.componentInstance;
-      primaryValueBar = progressElement.query(By.css('.mdc-linear-progress__primary-bar'))!;
-    }));
-
-    it('should not bind transition end listener', () => {
-      spyOn(primaryValueBar.nativeElement, 'addEventListener');
-      fixture.detectChanges();
-
-      expect(primaryValueBar.nativeElement.addEventListener).not.toHaveBeenCalled();
-    });
-
-    it('should trigger the animationEnd output on value set', () => {
-      fixture.detectChanges();
-      spyOn(progressComponent.animationEnd, 'next');
-
-      progressComponent.value = 40;
-      expect(progressComponent.animationEnd.next).toHaveBeenCalledWith({ value: 40 });
-    });
-  });
 });
 
 @Component({template: '<mat-progress-bar></mat-progress-bar>'})

src/material-experimental/mdc-progress-bar/progress-bar.ts

@@ -100,11 +100,6 @@ export class MatProgressBar extends _MatProgressBarMixinBase implements AfterVie
   set value(v: number) {
     this._value = clamp(v || 0);
     this._syncFoundation();
-
-    // When noop animation is set to true, trigger animationEnd directly.
-    if (this._isNoopAnimation) {
-      this._emitAnimationEnd();
-    }
   }
   private _value = 0;
 
@@ -162,16 +157,18 @@ export class MatProgressBar extends _MatProgressBarMixinBase implements AfterVie
     this._foundation.init();
     this._syncFoundation();
 
-    if (!this._isNoopAnimation) {
-      // Run outside angular so change detection didn't get triggered on every transition end
-      // instead only on the animation that we care about (primary value bar's transitionend)
-      this._ngZone.runOutsideAngular((() => {
-        this._animationEndSubscription =
-            (fromEvent(this._primaryBar, 'transitionend') as Observable<TransitionEvent>)
-              .pipe(filter(((e: TransitionEvent) => e.target === this._primaryBar)))
-              .subscribe(() => this._ngZone.run(() => this._emitAnimationEnd()));
-      }));
-    }
+    // Run outside angular so change detection didn't get triggered on every transition end
+    // instead only on the animation that we care about (primary value bar's transitionend)
+    this._ngZone.runOutsideAngular((() => {
+      this._animationEndSubscription =
+          (fromEvent(this._primaryBar, 'transitionend') as Observable<TransitionEvent>)
+            .pipe(filter(((e: TransitionEvent) => e.target === this._primaryBar)))
+            .subscribe(() => {
+              if (this.mode === 'determinate' || this.mode === 'buffer') {
+                this._ngZone.run(() => this.animationEnd.next({value: this.value}));
+              }
+            });
+    }));
   }
 
   ngOnDestroy() {
@@ -182,13 +179,6 @@ export class MatProgressBar extends _MatProgressBarMixinBase implements AfterVie
     this._dirChangeSubscription.unsubscribe();
   }
 
-  /** Emit an animationEnd event if in determinate or buffer mode. */
-  private _emitAnimationEnd(): void {
-    if (this.mode === 'determinate' || this.mode === 'buffer') {
-      this.animationEnd.next({value: this.value});
-    }
-  }
-
   /** Syncs the state of the progress bar with the MDC foundation. */
   private _syncFoundation() {
     const foundation = this._foundation;