Test: move getClatIpv6Address to common function

Share with EthernetTetheringTest and MtsEthernetTetheringTest

Bug: 258637850
Test: atest ConnectivityCoverageTests
Change-Id: I41daef082c30fdaafab44426ccaab4cb8b3297f3
diff --git a/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java b/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java
index 7685981..f2cf1d0 100644
--- a/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java
+++ b/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java
@@ -72,6 +72,8 @@
 
 import com.android.modules.utils.build.SdkLevel;
 import com.android.net.module.util.PacketBuilder;
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.structs.Ipv6Header;
 import com.android.testutils.HandlerUtils;
 import com.android.testutils.TapPacketReader;
 import com.android.testutils.TestNetworkTracker;
@@ -1013,6 +1015,18 @@
         return new TetheringTester(mDownstreamReader, mUpstreamReader);
     }
 
+    @NonNull
+    protected Inet6Address getClatIpv6Address(TetheringTester tester, TetheredDevice tethered)
+            throws Exception {
+        // Send an IPv4 UDP packet from client and check that a CLAT translated IPv6 UDP packet can
+        // be found on upstream interface. Get CLAT IPv6 address from the CLAT translated IPv6 UDP
+        // packet.
+        byte[] expectedPacket = probeV4TetheringConnectivity(tester, tethered, true /* is4To6 */);
+
+        // Above has guaranteed that the found packet is an IPv6 packet without ether header.
+        return Struct.parse(Ipv6Header.class, ByteBuffer.wrap(expectedPacket)).srcIp;
+    }
+
     protected <T> List<T> toList(T... array) {
         return Arrays.asList(array);
     }
diff --git a/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java b/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
index fb4b9fa..12ac454 100644
--- a/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
+++ b/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
@@ -62,7 +62,6 @@
 import com.android.net.module.util.structs.EthernetHeader;
 import com.android.net.module.util.structs.Icmpv4Header;
 import com.android.net.module.util.structs.Ipv4Header;
-import com.android.net.module.util.structs.Ipv6Header;
 import com.android.net.module.util.structs.UdpHeader;
 import com.android.testutils.DevSdkIgnoreRule;
 import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo;
@@ -522,18 +521,6 @@
         runUdp4Test();
     }
 
-    @NonNull
-    private Inet6Address getClatIpv6Address(TetheringTester tester, TetheredDevice tethered)
-            throws Exception {
-        // Send an IPv4 UDP packet from client and check that a CLAT translated IPv6 UDP packet can
-        // be found on upstream interface. Get CLAT IPv6 address from the CLAT translated IPv6 UDP
-        // packet.
-        byte[] expectedPacket = probeV4TetheringConnectivity(tester, tethered, true /* is4To6 */);
-
-        // Above has guaranteed that the found packet is an IPv6 packet without ether header.
-        return Struct.parse(Ipv6Header.class, ByteBuffer.wrap(expectedPacket)).srcIp;
-    }
-
     // Test network topology:
     //
     //            public network (rawip)                 private network