fix(progress-bar): changed after checked error on animation end event with noop animations (#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/progress-bar/progress-bar.scss

@@ -147,7 +147,10 @@ $mat-progress-bar-piece-animation-duration: 250ms !default;
     .mat-progress-bar-secondary.mat-progress-bar-fill::after,
     .mat-progress-bar-background {
       animation: none;
-      transition: none;
+
+      // Use a 1ms transition, because we have an event that
+      // is dispatched based on a `transitionend` being fired.
+      transition-duration: 1ms;
     }
   }
 }

src/material/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, MAT_PROGRESS_BAR_LOCATION} from './index';
 import {MatProgressBar} from './progress-bar';
 
@@ -261,33 +260,6 @@ describe('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('.mat-progress-bar-primary'))!;
-    }));
-
-    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/progress-bar/progress-bar.ts

@@ -134,11 +134,6 @@ export class MatProgressBar extends _MatProgressBarMixinBase implements CanColor
   get value(): number { return this._value; }
   set value(v: number) {
     this._value = clamp(coerceNumberProperty(v) || 0);
-
-    // When noop animation is set to true, trigger animationEnd directly.
-    if (this._isNoopAnimation) {
-      this._emitAnimationEnd();
-    }
   }
   private _value: number = 0;
 
@@ -194,31 +189,26 @@ export class MatProgressBar extends _MatProgressBarMixinBase implements CanColor
   }
 
   ngAfterViewInit() {
-    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((() => {
-        const element = this._primaryValueBar.nativeElement;
-
-        this._animationEndSubscription =
-            (fromEvent(element, 'transitionend') as Observable<TransitionEvent>)
-              .pipe(filter(((e: TransitionEvent) => e.target === element)))
-              .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((() => {
+      const element = this._primaryValueBar.nativeElement;
+
+      this._animationEndSubscription =
+        (fromEvent(element, 'transitionend') as Observable<TransitionEvent>)
+          .pipe(filter(((e: TransitionEvent) => e.target === element)))
+          .subscribe(() => {
+            if (this.mode === 'determinate' || this.mode === 'buffer') {
+              this._ngZone.run(() => this.animationEnd.next({value: this.value}));
+            }
+          });
+    }));
   }
 
   ngOnDestroy() {
     this._animationEndSubscription.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});
-    }
-  }
-
   static ngAcceptInputType_value: NumberInput;
 }