test(ivy): port TemplateRef tests over to acceptance tests (#30443)

- Moves template ref tests from render3 unit tests to acceptance tests.
- Marks tests testing ivy specific changes as `onlyInIvy`.
- Deletes old render3 unit tests that are no longer necessary

PR Close #30443

packages/core/test/acceptance/template_ref_spec.ts

@@ -9,6 +9,7 @@
 import {Component, TemplateRef, ViewChild, ViewContainerRef} from '@angular/core';
 import {TestBed} from '@angular/core/testing';
 import {expect} from '@angular/platform-browser/testing/src/matchers';
+import {onlyInIvy} from '@angular/private/testing';
 
 describe('TemplateRef', () => {
   describe('rootNodes', () => {
@@ -52,6 +53,117 @@ describe('TemplateRef', () => {
 
       expect(rootNodeTextContent).toEqual(['Header', 'Item one', 'Item two']);
     });
-  });
 
+    it('should return root render nodes for an embedded view instance', () => {
+      @Component({
+        template: `
+          <ng-template #templateRef>
+            <div></div>
+            some text
+            <span></span>
+          </ng-template>
+        `
+      })
+      class App {
+        @ViewChild('templateRef')
+        templateRef !: TemplateRef<any>;
+      }
+
+      TestBed.configureTestingModule({
+        declarations: [App],
+      });
+      const fixture = TestBed.createComponent(App);
+      fixture.detectChanges();
+
+      const embeddedView = fixture.componentInstance.templateRef.createEmbeddedView({});
+      expect(embeddedView.rootNodes.length).toBe(3);
+    });
+
+    /**
+     * This is different as compared to the view engine implementation which returns a comment node
+     * in this case:
+     * https://stackblitz.com/edit/angular-uiqry6?file=src/app/app.component.ts
+     *
+     * Returning a comment node for a template ref with no nodes is wrong is fixed in Ivy.
+     */
+    onlyInIvy('Fixed: Ivy no longer adds a comment node in this case.')
+        .it('should return an empty array for embedded view with no nodes', () => {
+          @Component({
+            template: `
+              <ng-template #templateRef></ng-template>
+            `
+          })
+          class App {
+            @ViewChild('templateRef')
+            templateRef !: TemplateRef<any>;
+          }
+
+          TestBed.configureTestingModule({
+            declarations: [App],
+          });
+          const fixture = TestBed.createComponent(App);
+          fixture.detectChanges();
+
+          const embeddedView = fixture.componentInstance.templateRef.createEmbeddedView({});
+          expect(embeddedView.rootNodes.length).toBe(0);
+        });
+
+    it('should not descend into containers when retrieving root nodes', () => {
+      /**
+       * NOTE: In VE, if `SUFFIX` text node below is _not_ present, VE will add an
+       * additional `<!---->` comment, thus being slightly different than Ivy.
+       * (resulting in 1 root node in Ivy and 2 in VE).
+       */
+      @Component({
+        template: `
+          <ng-template #templateRef><ng-template [ngIf]="true">text</ng-template>SUFFIX</ng-template>
+        `
+      })
+      class App {
+        @ViewChild('templateRef')
+        templateRef !: TemplateRef<any>;
+      }
+
+      TestBed.configureTestingModule({
+        declarations: [App],
+      });
+      const fixture = TestBed.createComponent(App);
+      fixture.detectChanges();
+
+      const embeddedView = fixture.componentInstance.templateRef.createEmbeddedView({});
+      expect(embeddedView.rootNodes.length).toBe(2);
+      expect(embeddedView.rootNodes[0].nodeType).toBe(Node.COMMENT_NODE);
+      expect(embeddedView.rootNodes[1].nodeType).toBe(Node.TEXT_NODE);
+    });
+
+    /**
+     * Contrary to containers (<ng-template>) we _do_ descend into element containers
+     * (<ng-container>)
+     */
+    it('should descend into element containers when retrieving root nodes', () => {
+      @Component({
+        template: `
+          <ng-template #templateRef>
+            <ng-container>text</ng-container>
+          </ng-template>
+        `
+      })
+      class App {
+        @ViewChild('templateRef')
+        templateRef !: TemplateRef<any>;
+      }
+
+      TestBed.configureTestingModule({
+        declarations: [App],
+      });
+      const fixture = TestBed.createComponent(App);
+      fixture.detectChanges();
+
+      const embeddedView = fixture.componentInstance.templateRef.createEmbeddedView({});
+
+      expect(embeddedView.rootNodes.length).toBe(2);
+      expect(embeddedView.rootNodes[0].nodeType).toBe(Node.COMMENT_NODE);
+      expect(embeddedView.rootNodes[1].nodeType).toBe(Node.TEXT_NODE);
+    });
+  });
 });