From 5c8b02104c59e344508a3942f655fee772b16311 Mon Sep 17 00:00:00 2001
From: Andrew Scott <atscott@google.com>
Date: Thu, 2 Nov 2023 13:02:35 -0700
Subject: [PATCH] test(core): Ensure signals can be read after view creation
 during change detection

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.
---
 .../change_detection_signals_in_zones_spec.ts | 49 ++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

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
index aafffb0dcca9..9195f0460fa8 100644
--- 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',