docs: add test case for #492 (#495)

Author: timdeschryver

projects/testing-library/tests/issues/issue-492.spec.ts

@@ -0,0 +1,48 @@
+import { AsyncPipe } from '@angular/common';
+import { Component, inject, Injectable } from '@angular/core';
+import { render, screen, waitFor } from '../../src/public_api';
+import { Observable, BehaviorSubject, map } from 'rxjs';
+
+test('displays username', async () => {
+  // stubbed user service using a Subject
+  const user = new BehaviorSubject({ name: 'username 1' });
+  const userServiceStub: Partial<UserService> = {
+    getName: () => user.asObservable().pipe(map((u) => u.name)),
+  };
+
+  // render the component with injection of the stubbed service
+  await render(UserComponent, {
+    componentProviders: [
+      {
+        provide: UserService,
+        useValue: userServiceStub,
+      },
+    ],
+  });
+
+  // assert first username emitted is rendered
+  expect(await screen.findByRole('heading')).toHaveTextContent('username 1');
+
+  // emitting a second username
+  user.next({ name: 'username 2' });
+
+  // assert the second username is rendered
+  await waitFor(() => expect(screen.getByRole('heading')).toHaveTextContent('username 2'));
+});
+
+@Component({
+  selector: 'atl-user',
+  standalone: true,
+  template: `<h1>{{ username$ | async }}</h1>`,
+  imports: [AsyncPipe],
+})
+class UserComponent {
+  readonly username$: Observable<string> = inject(UserService).getName();
+}
+
+@Injectable()
+class UserService {
+  getName(): Observable<string> {
+    throw new Error('Not implemented');
+  }
+}