diff --git a/Tethering/src/com/android/networkstack/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
index 75f63c8..5191bb7 100644
--- a/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -1975,6 +1975,10 @@
                 return;
             }
 
+            if (arg1 == UpstreamNetworkMonitor.NOTIFY_TEST_NETWORK_AVAILABLE) {
+                chooseUpstreamType(false);
+            }
+
             if (ns == null || !pertainsToCurrentUpstream(ns)) {
                 // TODO: In future, this is where upstream evaluation and selection
                 // could be handled for notifications which include sufficient data.
diff --git a/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
index 16c031b..15df0c6 100644
--- a/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
+++ b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
@@ -85,11 +85,12 @@
     private static final boolean DBG = false;
     private static final boolean VDBG = false;
 
-    public static final int EVENT_ON_CAPABILITIES   = 1;
-    public static final int EVENT_ON_LINKPROPERTIES = 2;
-    public static final int EVENT_ON_LOST           = 3;
-    public static final int EVENT_DEFAULT_SWITCHED  = 4;
-    public static final int NOTIFY_LOCAL_PREFIXES   = 10;
+    public static final int EVENT_ON_CAPABILITIES         = 1;
+    public static final int EVENT_ON_LINKPROPERTIES       = 2;
+    public static final int EVENT_ON_LOST                 = 3;
+    public static final int EVENT_DEFAULT_SWITCHED        = 4;
+    public static final int NOTIFY_LOCAL_PREFIXES         = 10;
+    public static final int NOTIFY_TEST_NETWORK_AVAILABLE = 11;
     // This value is used by deprecated preferredUpstreamIfaceTypes selection which is default
     // disabled.
     @VisibleForTesting
@@ -467,6 +468,17 @@
         notifyTarget(EVENT_DEFAULT_SWITCHED, ns);
     }
 
+    private void maybeHandleTestNetwork(@NonNull Network network) {
+        if (!mPreferTestNetworks) return;
+
+        final UpstreamNetworkState ns = mNetworkMap.get(network);
+        if (network.equals(mTetheringUpstreamNetwork) || !isTestNetwork(ns)) return;
+
+        // Test network is available. Notify tethering.
+        Log.d(TAG, "Handle test network: " + network);
+        notifyTarget(NOTIFY_TEST_NETWORK_AVAILABLE, ns);
+    }
+
     private void recomputeLocalPrefixes() {
         final HashSet<IpPrefix> localPrefixes = allLocalPrefixes(mNetworkMap.values());
         if (!mLocalPrefixes.equals(localPrefixes)) {
@@ -549,6 +561,12 @@
             // So it's not useful to do this work for non-LISTEN_ALL callbacks.
             if (mCallbackType == CALLBACK_LISTEN_ALL) {
                 recomputeLocalPrefixes();
+
+                // When the LISTEN_ALL network callback calls onLinkPropertiesChanged, it means that
+                // all the network information for the network is known (because
+                // onLinkPropertiesChanged is called after onAvailable and onCapabilitiesChanged).
+                // Inform tethering that the test network might have changed.
+                maybeHandleTestNetwork(network);
             }
         }
 
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/TestConnectivityManager.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TestConnectivityManager.java
index b2cbf75..e0d77ee 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/TestConnectivityManager.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TestConnectivityManager.java
@@ -19,6 +19,7 @@
 import static android.net.NetworkCapabilities.NET_CAPABILITY_DUN;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET;
 import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
+import static android.net.NetworkCapabilities.TRANSPORT_TEST;
 
 import static com.android.networkstack.apishim.common.ShimUtils.isAtLeastS;
 
@@ -329,6 +330,28 @@
             this.legacyType = toLegacyType(networkCapabilities);
         }
 
+        // Used for test network only because ConnectivityManager.networkCapabilitiesForType
+        // doesn't support "TRANSPORT_TEST -> TYPE_TEST" in #matchesLegacyType. Beware of
+        // satisfiedByNetworkCapabilities doesn't check on new |networkCapabilities| as
+        // #matchesLegacyType.
+        // TODO: refactor when tethering no longer uses CONNECTIVITY_ACTION.
+        private TestNetworkAgent(TestConnectivityManager cm) {
+            this.cm = cm;
+            networkId = new Network(cm.getNetworkId());
+            networkCapabilities = new NetworkCapabilities.Builder()
+                    .addTransportType(TRANSPORT_TEST)
+                    .addCapability(NET_CAPABILITY_INTERNET)
+                    .build();
+            linkProperties = new LinkProperties();
+            legacyType = TYPE_TEST;
+        }
+
+        // TODO: refactor when tethering no longer uses CONNECTIVITY_ACTION.
+        public static TestNetworkAgent buildTestNetworkAgentForTestNetwork(
+                TestConnectivityManager cm) {
+            return new TestNetworkAgent(cm);
+        }
+
         private static int toLegacyType(NetworkCapabilities nc) {
             for (int type = 0; type < ConnectivityManager.TYPE_TEST; type++) {
                 if (matchesLegacyType(nc, type)) return type;
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
index 9b9507b..b0cb7f2 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
@@ -449,6 +449,36 @@
     }
 
     @Test
+    public void testGetCurrentPreferredUpstream_TestNetworkPreferred() throws Exception {
+        mUNM.startTrackDefaultNetwork(mEntitleMgr);
+        mUNM.startObserveAllNetworks();
+        mUNM.setUpstreamConfig(true /* autoUpstream */, false /* dunRequired */);
+        mUNM.setTryCell(true);
+        mUNM.setPreferTestNetworks(true);
+
+        // [1] Mobile connects, DUN not required -> mobile selected.
+        final TestNetworkAgent cellAgent = new TestNetworkAgent(mCM, CELL_CAPABILITIES);
+        cellAgent.fakeConnect();
+        mCM.makeDefaultNetwork(cellAgent);
+        mLooper.dispatchAll();
+        assertEquals(cellAgent.networkId, mUNM.getCurrentPreferredUpstream().network);
+        assertEquals(0, mCM.mRequested.size());
+
+        // [2] Test network connects -> test network selected.
+        final TestNetworkAgent testAgent =
+                TestNetworkAgent.buildTestNetworkAgentForTestNetwork(mCM);
+        testAgent.fakeConnect();
+        mLooper.dispatchAll();
+        assertEquals(testAgent.networkId, mUNM.getCurrentPreferredUpstream().network);
+        assertEquals(0, mCM.mRequested.size());
+
+        // [3] Disable test networks preferred -> mobile selected.
+        mUNM.setPreferTestNetworks(false);
+        assertEquals(cellAgent.networkId, mUNM.getCurrentPreferredUpstream().network);
+        assertEquals(0, mCM.mRequested.size());
+    }
+
+    @Test
     public void testLocalPrefixes() throws Exception {
         mUNM.startTrackDefaultNetwork(mEntitleMgr);
         mUNM.startObserveAllNetworks();