From e7cf37d99f741c9570e81ebdb6085768f4c29b50 Mon Sep 17 00:00:00 2001
From: Sonu Kapoor <sonukapoor@gmail.com>
Date: Mon, 20 Jan 2020 22:24:28 -0500
Subject: [PATCH] docs: clarify where the `async` utility function is coming
 from (#34876) inside the `beforeEach` for out testing guide.

Fixes #34833

PR Close #34876
---
 aio/content/guide/testing.md | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/aio/content/guide/testing.md b/aio/content/guide/testing.md
index 2a0b292aa5..854b0afd95 100644
--- a/aio/content/guide/testing.md
+++ b/aio/content/guide/testing.md
@@ -618,6 +618,16 @@ It also generates an initial test file for the component, `banner-external.compo
   region="v1"
   header="app/banner/banner-external.component.spec.ts (initial)"></code-example>
 
+<div class="alert is-helpful">
+
+Because `compileComponents` is asynchronous, it uses 
+the [`async`](api/core/testing/async) utility 
+function imported from `@angular/core/testing`.
+
+Please refer to the [async](#async) section for more details.
+
+</div>
+
 #### Reduce the setup
 
 Only the last three lines of this file actually test the component