From 47e3788e3ec8b072f213551d7676b6a735094a96 Mon Sep 17 00:00:00 2001
From: markchien <markchien@google.com>
Date: Wed, 27 May 2020 18:16:37 +0800
Subject: [PATCH] Fix testTetheringUpstream flaky

testTetheringUpstream test case need cellular network. So it disable
wifi and getActiveNetwork to check whether current network is cellular.
But there is a race that call getActiveNetwork right away after
disconnect wifi. getActiveNetwork may return null because switching
network is not ready yet.

Bug: 156314879
Test: atest CtsTetheringTest

Change-Id: I6b433560fb27a3b4bd80c4198ccdb58a5be701b6
---
 .../android/tethering/cts/TetheringManagerTest.java   | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java b/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java
index 8665c7ed5e..10555312f7 100644
--- a/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java
+++ b/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java
@@ -56,6 +56,7 @@ import android.net.TetheringManager.TetheringEventCallback;
 import android.net.TetheringManager.TetheringInterfaceRegexps;
 import android.net.TetheringManager.TetheringRequest;
 import android.net.cts.util.CtsNetUtils;
+import android.net.cts.util.CtsNetUtils.TestNetworkCallback;
 import android.net.wifi.WifiManager;
 import android.os.Bundle;
 import android.os.PersistableBundle;
@@ -714,7 +715,15 @@ public class TetheringManagerTest {
                 mCtsNetUtils.disconnectFromWifi(null);
             }
 
-            final Network activeNetwork = mCm.getActiveNetwork();
+            final TestNetworkCallback networkCallback = new TestNetworkCallback();
+            Network activeNetwork = null;
+            try {
+                mCm.registerDefaultNetworkCallback(networkCallback);
+                activeNetwork = networkCallback.waitForAvailable();
+            } finally {
+                mCm.unregisterNetworkCallback(networkCallback);
+            }
+
             assertNotNull("No active network. Please ensure the device has working mobile data.",
                     activeNetwork);
             final NetworkCapabilities activeNetCap = mCm.getNetworkCapabilities(activeNetwork);