test(core): Ensure signals can be read after view creation during change detection (#52495)

atscott · thePunderWoman · commit da616ee773ac · 2023-11-13T18:24:41.000Z
These tests ensure signals can be read in a template after embedded views are created in the middle of template execution of an update pass. The embedded view templates are executed in create mode in the middle of the component template being executed in update mode. This behavior was found to not work correctly in past implementations of the reactive template consumers. PR Close #52495
diff --git a/packages/core/test/acceptance/change_detection_signals_in_zones_spec.ts b/packages/core/test/acceptance/change_detection_signals_in_zones_spec.ts
@@ -8,7 +8,7 @@
 
 import {NgFor, NgIf} from '@angular/common';
 import {PLATFORM_BROWSER_ID} from '@angular/common/src/platform_id';
-import {afterNextRender, ChangeDetectionStrategy, ChangeDetectorRef, Component, computed, Directive, inject, Input, PLATFORM_ID, signal, ViewChild} from '@angular/core';
+import {afterNextRender, ChangeDetectionStrategy, ChangeDetectorRef, Component, computed, Directive, inject, Input, PLATFORM_ID, signal, TemplateRef, ViewChild, ViewContainerRef} from '@angular/core';
 import {TestBed} from '@angular/core/testing';
 
 describe('CheckAlways components', () => {
@@ -628,6 +628,53 @@ describe('OnPush components with signals', () => {
   });
 
   describe('embedded views', () => {
+    describe('with a signal read after view creation during an update pass', () => {
+      it('should work with native control flow', () => {
+        @Component({
+          template: `
+        @if (true) { }
+        {{val()}}
+        `,
+          standalone: true,
+          changeDetection: ChangeDetectionStrategy.OnPush,
+        })
+        class MyComp {
+          val = signal('initial');
+        }
+
+        const fixture = TestBed.createComponent(MyComp);
+        fixture.detectChanges();
+        fixture.componentInstance.val.set('new');
+        fixture.detectChanges();
+        expect(fixture.nativeElement.innerText).toBe('new');
+      });
+
+      it('should work with createEmbeddedView', () => {
+        @Component({
+          template: `
+        <ng-template #template></ng-template>
+        {{createEmbeddedView(template)}}
+        {{val()}}
+        `,
+          standalone: true,
+          changeDetection: ChangeDetectionStrategy.OnPush,
+        })
+        class MyComp {
+          val = signal('initial');
+          vcr = inject(ViewContainerRef);
+          createEmbeddedView(ref: TemplateRef<{}>) {
+            this.vcr.createEmbeddedView(ref);
+          }
+        }
+
+        const fixture = TestBed.createComponent(MyComp);
+        fixture.detectChanges();
+        fixture.componentInstance.val.set('new');
+        fixture.detectChanges();
+        expect(fixture.nativeElement.innerText).toBe('new');
+      });
+    });
+
     it('refreshes an embedded view in a component', () => {
       @Component({
         selector: 'signal-component',
