Merge "Fix EtherentTetheringTest flaky" into main

Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java

@@ -58,6 +58,8 @@ import android.net.TetheringManager.TetheringEventCallback;
 import android.net.TetheringManager.TetheringRequest;
 import android.net.TetheringTester.TetheredDevice;
 import android.net.cts.util.CtsNetUtils;
+import android.net.cts.util.CtsTetheringUtils;
+import android.net.cts.util.CtsTetheringUtils.TestTetheringEventCallback;
 import android.os.Handler;
 import android.os.HandlerThread;
 import android.os.SystemClock;
@@ -75,6 +77,7 @@ import com.android.testutils.TestNetworkTracker;
 
 import org.junit.After;
 import org.junit.Before;
+import org.junit.BeforeClass;
 
 import java.io.FileDescriptor;
 import java.net.Inet4Address;
@@ -161,6 +164,28 @@ public abstract class EthernetTetheringTestBase {
     private TapPacketReader mDownstreamReader;
     private MyTetheringEventCallback mTetheringEventCallback;
 
+    @BeforeClass
+    public static void setUpOnce() throws Exception {
+        // The first test case may experience tethering restart with IP conflict handling.
+        // Tethering would cache the last upstreams so that the next enabled tethering avoids
+        // picking up the address that is in conflict with the upstreams. To protect subsequent
+        // tests, turn tethering on and off before running them.
+        final Context ctx = InstrumentationRegistry.getInstrumentation().getContext();
+        final CtsTetheringUtils utils = new CtsTetheringUtils(ctx);
+        final TestTetheringEventCallback callback = utils.registerTetheringEventCallback();
+        try {
+            if (!callback.isWifiTetheringSupported(ctx)) return;
+
+            callback.expectNoTetheringActive();
+
+            utils.startWifiTethering(callback);
+            callback.getCurrentValidUpstream();
+            utils.stopWifiTethering(callback);
+        } finally {
+            utils.unregisterTetheringEventCallback(callback);
+        }
+    }
+
     @Before
     public void setUp() throws Exception {
         mHandlerThread = new HandlerThread(getClass().getSimpleName());

tests/cts/net/util/java/android/net/cts/util/CtsTetheringUtils.java

@@ -393,21 +393,28 @@ public final class CtsTetheringUtils {
         }
 
         public void assumeTetheringSupported() {
+            assumeTrue(isTetheringSupported());
+        }
+
+        private boolean isTetheringSupported() {
             final ArrayTrackRecord<CallbackValue>.ReadHead history =
                     mHistory.newReadHead();
-            assertNotNull("No onSupported callback", history.poll(TIMEOUT_MS, (cv) -> {
+            final CallbackValue result = history.poll(TIMEOUT_MS, (cv) -> {
-                if (cv.callbackType != CallbackType.ON_SUPPORTED) return false;
+                return cv.callbackType == CallbackType.ON_SUPPORTED;
+            });
 
-                assumeTrue(cv.callbackParam2 == 1 /* supported */);
+            assertNotNull("No onSupported callback", result);
-                return true;
+            return result.callbackParam2 == 1 /* supported */;
-            }));
         }
 
         public void assumeWifiTetheringSupported(final Context ctx) throws Exception {
-            assumeTetheringSupported();
+            assumeTrue(isWifiTetheringSupported(ctx));
+        }
 
-            assumeTrue(!getTetheringInterfaceRegexps().getTetherableWifiRegexs().isEmpty());
+        public boolean isWifiTetheringSupported(final Context ctx) throws Exception {
-            assumeTrue(isPortableHotspotSupported(ctx));
+            return isTetheringSupported()
+                    && !getTetheringInterfaceRegexps().getTetherableWifiRegexs().isEmpty()
+                    && isPortableHotspotSupported(ctx);
         }
 
         public TetheringInterfaceRegexps getTetheringInterfaceRegexps() {