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 3a6350c..3636b03 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/TestConnectivityManager.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TestConnectivityManager.java
@@ -16,19 +16,20 @@
 
 package com.android.networkstack.tethering;
 
-import static android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET;
-
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.fail;
 
 import android.content.Context;
+import android.content.Intent;
 import android.net.ConnectivityManager;
 import android.net.IConnectivityManager;
 import android.net.LinkProperties;
 import android.net.Network;
 import android.net.NetworkCapabilities;
+import android.net.NetworkInfo;
 import android.net.NetworkRequest;
 import android.os.Handler;
+import android.os.UserHandle;
 
 import java.util.HashMap;
 import java.util.HashSet;
@@ -39,6 +40,10 @@
 /**
  * Simulates upstream switching and sending NetworkCallbacks and CONNECTIVITY_ACTION broadcasts.
  *
+ * Unlike any real networking code, this class is single-threaded and entirely synchronous.
+ * The effects of all method calls (including sending fake broadcasts, sending callbacks, etc.) are
+ * performed immediately on the caller's thread before returning.
+ *
  * TODO: this duplicates a fair amount of code from ConnectivityManager and ConnectivityService.
  * Consider using a ConnectivityService object instead, as used in ConnectivityServiceTest.
  *
@@ -63,11 +68,21 @@
     public Map<NetworkCallback, Integer> legacyTypeMap = new HashMap<>();
 
     private final NetworkRequest mDefaultRequest;
+    private final Context mContext;
+
     private int mNetworkId = 100;
 
+    /**
+     * Constructs a TestConnectivityManager.
+     * @param ctx the context to use. Must be a fake or a mock because otherwise the test will
+     *            attempt to send real broadcasts and resulting in permission denials.
+     * @param svc an IConnectivityManager. Should be a fake or a mock.
+     * @param defaultRequest the default NetworkRequest that will be used by Tethering.
+     */
     public TestConnectivityManager(Context ctx, IConnectivityManager svc,
             NetworkRequest defaultRequest) {
         super(ctx, svc);
+        mContext = ctx;
         mDefaultRequest = defaultRequest;
     }
 
@@ -109,6 +124,13 @@
         final TestNetworkAgent formerDefault = defaultNetwork;
         defaultNetwork = agent;
 
+        if (formerDefault != null) {
+            sendConnectivityAction(formerDefault.legacyType, false /* connected */);
+        }
+        if (defaultNetwork != null) {
+            sendConnectivityAction(defaultNetwork.legacyType, true /* connected */);
+        }
+
         for (NetworkCallback cb : trackingDefault) {
             if (defaultNetwork != null) {
                 cb.onAvailable(defaultNetwork.networkId);
@@ -194,24 +216,72 @@
         assertFalse(requested.containsKey(cb));
     }
 
+    private void sendConnectivityAction(int type, boolean connected) {
+        NetworkInfo ni = new NetworkInfo(type, 0 /* subtype */,  getNetworkTypeName(type),
+                "" /* subtypeName */);
+        NetworkInfo.DetailedState state = connected
+                ? NetworkInfo.DetailedState.CONNECTED
+                : NetworkInfo.DetailedState.DISCONNECTED;
+        ni.setDetailedState(state, "" /* reason */, "" /* extraInfo */);
+        Intent intent = new Intent(CONNECTIVITY_ACTION);
+        intent.putExtra(EXTRA_NETWORK_INFO, ni);
+        mContext.sendStickyBroadcastAsUser(intent, UserHandle.ALL);
+    }
+
     public static class TestNetworkAgent {
         public final TestConnectivityManager cm;
         public final Network networkId;
-        public final int transportType;
         public final NetworkCapabilities networkCapabilities;
         public final LinkProperties linkProperties;
+        // TODO: delete when tethering no longer uses CONNECTIVITY_ACTION.
+        public final int legacyType;
 
-        public TestNetworkAgent(TestConnectivityManager cm, int transportType) {
+        public TestNetworkAgent(TestConnectivityManager cm, NetworkCapabilities nc) {
             this.cm = cm;
             this.networkId = new Network(cm.getNetworkId());
-            this.transportType = transportType;
-            networkCapabilities = new NetworkCapabilities();
-            networkCapabilities.addTransportType(transportType);
-            networkCapabilities.addCapability(NET_CAPABILITY_INTERNET);
+            networkCapabilities = copy(nc);
             linkProperties = new LinkProperties();
+            legacyType = toLegacyType(nc);
+        }
+
+        public TestNetworkAgent(TestConnectivityManager cm, UpstreamNetworkState state) {
+            this.cm = cm;
+            networkId = state.network;
+            networkCapabilities = state.networkCapabilities;
+            linkProperties = state.linkProperties;
+            this.legacyType = toLegacyType(networkCapabilities);
+        }
+
+        private static int toLegacyType(NetworkCapabilities nc) {
+            for (int type = 0; type < ConnectivityManager.TYPE_TEST; type++) {
+                if (matchesLegacyType(nc, type)) return type;
+            }
+            throw new IllegalArgumentException(("Can't determine legacy type for: ") + nc);
+        }
+
+        private static boolean matchesLegacyType(NetworkCapabilities nc, int legacyType) {
+            final NetworkCapabilities typeNc;
+            try {
+                typeNc = ConnectivityManager.networkCapabilitiesForType(legacyType);
+            } catch (IllegalArgumentException e) {
+                // networkCapabilitiesForType does not support all legacy types.
+                return false;
+            }
+            return typeNc.satisfiedByNetworkCapabilities(nc);
+        }
+
+        private boolean matchesLegacyType(int legacyType) {
+            return matchesLegacyType(networkCapabilities, legacyType);
         }
 
         public void fakeConnect() {
+            for (NetworkRequest request : cm.requested.values()) {
+                if (matchesLegacyType(request.legacyType)) {
+                    cm.sendConnectivityAction(legacyType, true /* connected */);
+                    // In practice, a given network can match only one legacy type.
+                    break;
+                }
+            }
             for (NetworkCallback cb : cm.listening.keySet()) {
                 cb.onAvailable(networkId);
                 cb.onCapabilitiesChanged(networkId, copy(networkCapabilities));
@@ -220,6 +290,12 @@
         }
 
         public void fakeDisconnect() {
+            for (NetworkRequest request : cm.requested.values()) {
+                if (matchesLegacyType(request.legacyType)) {
+                    cm.sendConnectivityAction(legacyType, false /* connected */);
+                    break;
+                }
+            }
             for (NetworkCallback cb : cm.listening.keySet()) {
                 cb.onLost(networkId);
             }
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 e358f5a..7d735fc 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
@@ -85,6 +85,13 @@
     // any specific TRANSPORT_* is sufficient to identify this request.
     private static final NetworkRequest sDefaultRequest = new NetworkRequest.Builder().build();
 
+    private static final NetworkCapabilities CELL_CAPABILITIES = new NetworkCapabilities.Builder()
+            .addTransportType(TRANSPORT_CELLULAR).addCapability(NET_CAPABILITY_INTERNET).build();
+    private static final NetworkCapabilities DUN_CAPABILITIES = new NetworkCapabilities.Builder()
+            .addTransportType(TRANSPORT_CELLULAR).addCapability(NET_CAPABILITY_DUN).build();
+    private static final NetworkCapabilities WIFI_CAPABILITIES = new NetworkCapabilities.Builder()
+            .addTransportType(TRANSPORT_WIFI).addCapability(NET_CAPABILITY_INTERNET).build();
+
     @Mock private Context mContext;
     @Mock private EntitlementManager mEntitleMgr;
     @Mock private IConnectivityManager mCS;
@@ -288,7 +295,7 @@
         // There are no networks, so there is nothing to select.
         assertSatisfiesLegacyType(TYPE_NONE, mUNM.selectPreferredUpstreamType(preferredTypes));
 
-        final TestNetworkAgent wifiAgent = new TestNetworkAgent(mCM, TRANSPORT_WIFI);
+        final TestNetworkAgent wifiAgent = new TestNetworkAgent(mCM, WIFI_CAPABILITIES);
         wifiAgent.fakeConnect();
         // WiFi is up, we should prefer it.
         assertSatisfiesLegacyType(TYPE_WIFI, mUNM.selectPreferredUpstreamType(preferredTypes));
@@ -296,7 +303,7 @@
         // There are no networks, so there is nothing to select.
         assertSatisfiesLegacyType(TYPE_NONE, mUNM.selectPreferredUpstreamType(preferredTypes));
 
-        final TestNetworkAgent cellAgent = new TestNetworkAgent(mCM, TRANSPORT_CELLULAR);
+        final TestNetworkAgent cellAgent = new TestNetworkAgent(mCM, CELL_CAPABILITIES);
         cellAgent.fakeConnect();
         assertSatisfiesLegacyType(TYPE_NONE, mUNM.selectPreferredUpstreamType(preferredTypes));
 
@@ -337,8 +344,7 @@
         mUNM.updateMobileRequiresDun(true);
         assertSatisfiesLegacyType(TYPE_WIFI, mUNM.selectPreferredUpstreamType(preferredTypes));
 
-        final TestNetworkAgent dunAgent = new TestNetworkAgent(mCM, TRANSPORT_CELLULAR);
-        dunAgent.networkCapabilities.addCapability(NET_CAPABILITY_DUN);
+        final TestNetworkAgent dunAgent = new TestNetworkAgent(mCM, DUN_CAPABILITIES);
         dunAgent.fakeConnect();
 
         // WiFi is still preferred.
@@ -370,7 +376,7 @@
         mUNM.updateMobileRequiresDun(false);
 
         // [0] Mobile connects, DUN not required -> mobile selected.
-        final TestNetworkAgent cellAgent = new TestNetworkAgent(mCM, TRANSPORT_CELLULAR);
+        final TestNetworkAgent cellAgent = new TestNetworkAgent(mCM, CELL_CAPABILITIES);
         cellAgent.fakeConnect();
         mCM.makeDefaultNetwork(cellAgent);
         assertEquals(cellAgent.networkId, mUNM.getCurrentPreferredUpstream().network);
@@ -381,7 +387,7 @@
         when(mEntitleMgr.isCellularUpstreamPermitted()).thenReturn(true);
 
         // [2] WiFi connects but not validated/promoted to default -> mobile selected.
-        final TestNetworkAgent wifiAgent = new TestNetworkAgent(mCM, TRANSPORT_WIFI);
+        final TestNetworkAgent wifiAgent = new TestNetworkAgent(mCM, WIFI_CAPABILITIES);
         wifiAgent.fakeConnect();
         assertEquals(cellAgent.networkId, mUNM.getCurrentPreferredUpstream().network);
 
@@ -401,7 +407,7 @@
         // into UNM we should test for this here.
 
         // [6] DUN network arrives -> DUN selected
-        final TestNetworkAgent dunAgent = new TestNetworkAgent(mCM, TRANSPORT_CELLULAR);
+        final TestNetworkAgent dunAgent = new TestNetworkAgent(mCM, CELL_CAPABILITIES);
         dunAgent.networkCapabilities.addCapability(NET_CAPABILITY_DUN);
         dunAgent.networkCapabilities.removeCapability(NET_CAPABILITY_INTERNET);
         dunAgent.fakeConnect();
@@ -424,7 +430,7 @@
         final Set<String> alreadySeen = new HashSet<>();
 
         // [1] Pretend Wi-Fi connects.
-        final TestNetworkAgent wifiAgent = new TestNetworkAgent(mCM, TRANSPORT_WIFI);
+        final TestNetworkAgent wifiAgent = new TestNetworkAgent(mCM, WIFI_CAPABILITIES);
         final LinkProperties wifiLp = wifiAgent.linkProperties;
         wifiLp.setInterfaceName("wlan0");
         final String[] wifi_addrs = {
@@ -451,7 +457,7 @@
         assertEquals(alreadySeen.size(), local.size());
 
         // [2] Pretend mobile connects.
-        final TestNetworkAgent cellAgent = new TestNetworkAgent(mCM, TRANSPORT_CELLULAR);
+        final TestNetworkAgent cellAgent = new TestNetworkAgent(mCM, CELL_CAPABILITIES);
         final LinkProperties cellLp = cellAgent.linkProperties;
         cellLp.setInterfaceName("rmnet_data0");
         final String[] cell_addrs = {
@@ -472,9 +478,7 @@
         assertEquals(alreadySeen.size(), local.size());
 
         // [3] Pretend DUN connects.
-        final TestNetworkAgent dunAgent = new TestNetworkAgent(mCM, TRANSPORT_CELLULAR);
-        dunAgent.networkCapabilities.addCapability(NET_CAPABILITY_DUN);
-        dunAgent.networkCapabilities.removeCapability(NET_CAPABILITY_INTERNET);
+        final TestNetworkAgent dunAgent = new TestNetworkAgent(mCM, DUN_CAPABILITIES);
         final LinkProperties dunLp = dunAgent.linkProperties;
         dunLp.setInterfaceName("rmnet_data1");
         final String[] dun_addrs = {
@@ -524,11 +528,11 @@
         mUNM.startTrackDefaultNetwork(sDefaultRequest, mEntitleMgr);
         mUNM.startObserveAllNetworks();
         // Setup wifi and make wifi as default network.
-        final TestNetworkAgent wifiAgent = new TestNetworkAgent(mCM, TRANSPORT_WIFI);
+        final TestNetworkAgent wifiAgent = new TestNetworkAgent(mCM, WIFI_CAPABILITIES);
         wifiAgent.fakeConnect();
         mCM.makeDefaultNetwork(wifiAgent);
         // Setup mobile network.
-        final TestNetworkAgent cellAgent = new TestNetworkAgent(mCM, TRANSPORT_CELLULAR);
+        final TestNetworkAgent cellAgent = new TestNetworkAgent(mCM, CELL_CAPABILITIES);
         cellAgent.fakeConnect();
 
         assertSatisfiesLegacyType(TYPE_MOBILE_HIPRI,