Skip testPhysicalEthernet if the test run adb over network

If the test run adb over network and ethernet is available, it is likely
that adb may run over ethernet. Then the test would fail because adb
would break when ethernet is switching from client mode to server mode.

Bug: 160389275
Test: atest CtsTetheringTest

Change-Id: I57d365d33316881c50c3bf7fd1c98926d10842d3

Tethering/tests/integration/src/android/net/EthernetTetheringTest.java

@@ -42,6 +42,7 @@ import android.net.dhcp.DhcpPacket;
 import android.os.Handler;
 import android.os.HandlerThread;
 import android.os.SystemClock;
+import android.os.SystemProperties;
 import android.system.Os;
 import android.util.Log;
 
@@ -224,9 +225,19 @@ public class EthernetTetheringTest {
 
     }
 
+    private boolean isAdbOverNetwork() {
+        // If adb TCP port opened, this test may running by adb over network.
+        return (SystemProperties.getInt("persist.adb.tcp.port", -1) > -1)
+                || (SystemProperties.getInt("service.adb.tcp.port", -1) > -1);
+    }
+
     @Test
     public void testPhysicalEthernet() throws Exception {
         assumeTrue(mEm.isAvailable());
+        // Do not run this test if adb is over network and ethernet is connected.
+        // It is likely the adb run over ethernet, the adb would break when ethernet is switching
+        // from client mode to server mode. See b/160389275.
+        assumeFalse(isAdbOverNetwork());
 
         // Get an interface to use.
         final String iface = mTetheredInterfaceRequester.getInterface();