diff --git a/framework/Android.bp b/framework/Android.bp
index 9da27d2..86b85e8 100644
--- a/framework/Android.bp
+++ b/framework/Android.bp
@@ -23,7 +23,6 @@
     default_applicable_licenses: ["frameworks_base_license"],
 }
 
-// TODO: use a java_library in the bootclasspath instead
 filegroup {
     name: "framework-connectivity-internal-sources",
     srcs: [
diff --git a/framework/api/module-lib-current.txt b/framework/api/module-lib-current.txt
index d2ed73e..6df57c1 100644
--- a/framework/api/module-lib-current.txt
+++ b/framework/api/module-lib-current.txt
@@ -51,6 +51,14 @@
     field public static final String TEST_TAP_PREFIX = "testtap";
   }
 
+  public final class TestNetworkSpecifier extends android.net.NetworkSpecifier implements android.os.Parcelable {
+    ctor public TestNetworkSpecifier(@NonNull String);
+    method public int describeContents();
+    method @Nullable public String getInterfaceName();
+    method public void writeToParcel(@NonNull android.os.Parcel, int);
+    field @NonNull public static final android.os.Parcelable.Creator<android.net.TestNetworkSpecifier> CREATOR;
+  }
+
   public final class VpnTransportInfo implements android.os.Parcelable android.net.TransportInfo {
     ctor public VpnTransportInfo(int);
     method public int describeContents();
diff --git a/framework/src/android/net/ConnectivityManager.java b/framework/src/android/net/ConnectivityManager.java
index 45ed317..bbf4559 100644
--- a/framework/src/android/net/ConnectivityManager.java
+++ b/framework/src/android/net/ConnectivityManager.java
@@ -2275,7 +2275,7 @@
             @NonNull String callingPackage, @Nullable String callingAttributionTag,
             boolean throwException) {
         return Settings.checkAndNoteWriteSettingsOperation(context, uid, callingPackage,
-                throwException);
+                callingAttributionTag, throwException);
     }
 
     /**
diff --git a/framework/src/android/net/NetworkRequest.java b/framework/src/android/net/NetworkRequest.java
index b4a651c..17a8ee1 100644
--- a/framework/src/android/net/NetworkRequest.java
+++ b/framework/src/android/net/NetworkRequest.java
@@ -31,6 +31,7 @@
 import static android.net.NetworkCapabilities.NET_CAPABILITY_TEMPORARILY_NOT_METERED;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_TRUSTED;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED;
+import static android.net.NetworkCapabilities.TRANSPORT_TEST;
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
@@ -382,11 +383,17 @@
                 return setNetworkSpecifier(new TelephonyNetworkSpecifier.Builder()
                         .setSubscriptionId(subId).build());
             } catch (NumberFormatException nfe) {
-                // A StringNetworkSpecifier does not accept null or empty ("") strings. When network
-                // specifiers were strings a null string and an empty string were considered
-                // equivalent. Hence no meaning is attached to a null or empty ("") string.
-                return setNetworkSpecifier(TextUtils.isEmpty(networkSpecifier) ? null
-                        : new StringNetworkSpecifier(networkSpecifier));
+                // An EthernetNetworkSpecifier or TestNetworkSpecifier does not accept null or empty
+                // ("") strings. When network specifiers were strings a null string and an empty
+                // string were considered equivalent. Hence no meaning is attached to a null or
+                // empty ("") string.
+                if (TextUtils.isEmpty(networkSpecifier)) {
+                    return setNetworkSpecifier((NetworkSpecifier) null);
+                } else if (mNetworkCapabilities.hasTransport(TRANSPORT_TEST)) {
+                    return setNetworkSpecifier(new TestNetworkSpecifier(networkSpecifier));
+                } else {
+                    return setNetworkSpecifier(new EthernetNetworkSpecifier(networkSpecifier));
+                }
             }
         }
 
diff --git a/framework/src/android/net/TestNetworkSpecifier.java b/framework/src/android/net/TestNetworkSpecifier.java
new file mode 100644
index 0000000..b7470a5
--- /dev/null
+++ b/framework/src/android/net/TestNetworkSpecifier.java
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.SystemApi;
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.text.TextUtils;
+
+import com.android.internal.util.Preconditions;
+
+import java.util.Objects;
+
+/**
+ * A {@link NetworkSpecifier} used to identify test interfaces.
+ *
+ * @see TestNetworkManager
+ * @hide
+ */
+@SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
+public final class TestNetworkSpecifier extends NetworkSpecifier implements Parcelable {
+
+    /**
+     * Name of the network interface.
+     */
+    @NonNull
+    private final String mInterfaceName;
+
+    public TestNetworkSpecifier(@NonNull String interfaceName) {
+        Preconditions.checkStringNotEmpty(interfaceName);
+        mInterfaceName = interfaceName;
+    }
+
+    // This may be null in the future to support specifiers based on data other than the interface
+    // name.
+    @Nullable
+    public String getInterfaceName() {
+        return mInterfaceName;
+    }
+
+    @Override
+    public boolean canBeSatisfiedBy(@Nullable NetworkSpecifier other) {
+        return equals(other);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (!(o instanceof TestNetworkSpecifier)) return false;
+        return TextUtils.equals(mInterfaceName, ((TestNetworkSpecifier) o).mInterfaceName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(mInterfaceName);
+    }
+
+    @Override
+    public String toString() {
+        return "TestNetworkSpecifier (" + mInterfaceName + ")";
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(@NonNull Parcel dest, int flags) {
+        dest.writeString(mInterfaceName);
+    }
+
+    public static final @NonNull Creator<TestNetworkSpecifier> CREATOR =
+            new Creator<TestNetworkSpecifier>() {
+        public TestNetworkSpecifier createFromParcel(Parcel in) {
+            return new TestNetworkSpecifier(in.readString());
+        }
+        public TestNetworkSpecifier[] newArray(int size) {
+            return new TestNetworkSpecifier[size];
+        }
+    };
+}
diff --git a/services/core/java/com/android/server/TestNetworkService.java b/services/core/java/com/android/server/TestNetworkService.java
index 55408ea..ee61067 100644
--- a/services/core/java/com/android/server/TestNetworkService.java
+++ b/services/core/java/com/android/server/TestNetworkService.java
@@ -33,8 +33,8 @@
 import android.net.NetworkCapabilities;
 import android.net.NetworkProvider;
 import android.net.RouteInfo;
-import android.net.StringNetworkSpecifier;
 import android.net.TestNetworkInterface;
+import android.net.TestNetworkSpecifier;
 import android.net.util.NetdService;
 import android.os.Binder;
 import android.os.Handler;
@@ -242,7 +242,7 @@
         nc.addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_SUSPENDED);
         nc.addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED);
         nc.addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VCN_MANAGED);
-        nc.setNetworkSpecifier(new StringNetworkSpecifier(iface));
+        nc.setNetworkSpecifier(new TestNetworkSpecifier(iface));
         nc.setAdministratorUids(administratorUids);
         if (!isMetered) {
             nc.addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_METERED);
diff --git a/tests/net/common/java/android/net/NetworkCapabilitiesTest.java b/tests/net/common/java/android/net/NetworkCapabilitiesTest.java
index 5d0e016..ddc31bf 100644
--- a/tests/net/common/java/android/net/NetworkCapabilitiesTest.java
+++ b/tests/net/common/java/android/net/NetworkCapabilitiesTest.java
@@ -211,7 +211,7 @@
         nc1 = new NetworkCapabilities().addTransportType(TRANSPORT_WIFI);
         nc2 = new NetworkCapabilities()
                 .addTransportType(TRANSPORT_WIFI)
-                .setNetworkSpecifier(new StringNetworkSpecifier("specs"));
+                .setNetworkSpecifier(new EthernetNetworkSpecifier("eth42"));
         assertNotEquals("", nc1.describeImmutableDifferences(nc2));
         assertEquals("", nc1.describeImmutableDifferences(nc1));
     }
@@ -671,7 +671,7 @@
         NetworkCapabilities nc1 = new NetworkCapabilities();
         nc1.addTransportType(TRANSPORT_CELLULAR).addTransportType(TRANSPORT_WIFI);
         try {
-            nc1.setNetworkSpecifier(new StringNetworkSpecifier("specs"));
+            nc1.setNetworkSpecifier(new EthernetNetworkSpecifier("eth0"));
             fail("Cannot set NetworkSpecifier on a NetworkCapability with multiple transports!");
         } catch (IllegalStateException expected) {
             // empty
@@ -680,7 +680,7 @@
         // Sequence 2: Transport + NetworkSpecifier + Transport
         NetworkCapabilities nc2 = new NetworkCapabilities();
         nc2.addTransportType(TRANSPORT_CELLULAR).setNetworkSpecifier(
-                new StringNetworkSpecifier("specs"));
+                new EthernetNetworkSpecifier("testtap3"));
         try {
             nc2.addTransportType(TRANSPORT_WIFI);
             fail("Cannot set a second TransportType of a network which has a NetworkSpecifier!");
diff --git a/tests/net/common/java/android/net/NetworkProviderTest.kt b/tests/net/common/java/android/net/NetworkProviderTest.kt
index bcc9072..71a7a7c 100644
--- a/tests/net/common/java/android/net/NetworkProviderTest.kt
+++ b/tests/net/common/java/android/net/NetworkProviderTest.kt
@@ -102,7 +102,7 @@
         mCm.registerNetworkProvider(provider)
         assertNotEquals(provider.getProviderId(), NetworkProvider.ID_NONE)
 
-        val specifier = StringNetworkSpecifier(UUID.randomUUID().toString())
+        val specifier = EthernetNetworkSpecifier(UUID.randomUUID().toString())
         val nr: NetworkRequest = NetworkRequest.Builder()
                 .addTransportType(TRANSPORT_TEST)
                 .setNetworkSpecifier(specifier)
@@ -183,7 +183,7 @@
 
         mCm.registerNetworkProvider(provider)
 
-        val specifier = StringNetworkSpecifier(UUID.randomUUID().toString())
+        val specifier = EthernetNetworkSpecifier(UUID.randomUUID().toString())
         val nr: NetworkRequest = NetworkRequest.Builder()
                 .addTransportType(TRANSPORT_TEST)
                 .setNetworkSpecifier(specifier)
diff --git a/tests/net/java/com/android/server/ConnectivityServiceTest.java b/tests/net/java/com/android/server/ConnectivityServiceTest.java
index a643bc8..2c6a21a 100644
--- a/tests/net/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/net/java/com/android/server/ConnectivityServiceTest.java
@@ -3718,7 +3718,7 @@
      * @return the context's attribution tag
      */
     private String getAttributionTag() {
-        return null;
+        return mContext.getAttributionTag();
     }
 
     @Test
diff --git a/tests/net/java/com/android/server/connectivity/MultipathPolicyTrackerTest.java b/tests/net/java/com/android/server/connectivity/MultipathPolicyTrackerTest.java
index 950d716..38f6d7f 100644
--- a/tests/net/java/com/android/server/connectivity/MultipathPolicyTrackerTest.java
+++ b/tests/net/java/com/android/server/connectivity/MultipathPolicyTrackerTest.java
@@ -46,12 +46,12 @@
 import android.content.pm.ApplicationInfo;
 import android.content.res.Resources;
 import android.net.ConnectivityManager;
+import android.net.EthernetNetworkSpecifier;
 import android.net.Network;
 import android.net.NetworkCapabilities;
 import android.net.NetworkPolicy;
 import android.net.NetworkPolicyManager;
 import android.net.NetworkTemplate;
-import android.net.StringNetworkSpecifier;
 import android.net.TelephonyNetworkSpecifier;
 import android.os.Handler;
 import android.os.UserHandle;
@@ -240,7 +240,7 @@
         NetworkCapabilities capabilities = new NetworkCapabilities()
                 .addCapability(NET_CAPABILITY_INTERNET)
                 .addTransportType(TRANSPORT_CELLULAR)
-                .setNetworkSpecifier(new StringNetworkSpecifier("234"));
+                .setNetworkSpecifier(new EthernetNetworkSpecifier("eth234"));
         if (!roaming) {
             capabilities.addCapability(NET_CAPABILITY_NOT_ROAMING);
         }
diff --git a/tests/net/java/com/android/server/connectivity/NetworkNotificationManagerTest.java b/tests/net/java/com/android/server/connectivity/NetworkNotificationManagerTest.java
index ff8c632..d01dc03 100644
--- a/tests/net/java/com/android/server/connectivity/NetworkNotificationManagerTest.java
+++ b/tests/net/java/com/android/server/connectivity/NetworkNotificationManagerTest.java
@@ -20,6 +20,7 @@
 
 import static org.mockito.Mockito.any;
 import static org.mockito.Mockito.anyInt;
+import static org.mockito.Mockito.clearInvocations;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.eq;
 import static org.mockito.Mockito.mock;
@@ -39,6 +40,7 @@
 import android.net.NetworkInfo;
 import android.os.UserHandle;
 import android.telephony.TelephonyManager;
+import android.util.DisplayMetrics;
 
 import androidx.test.filters.SmallTest;
 import androidx.test.runner.AndroidJUnit4;
@@ -88,6 +90,7 @@
 
     @Mock Context mCtx;
     @Mock Resources mResources;
+    @Mock DisplayMetrics mDisplayMetrics;
     @Mock PackageManager mPm;
     @Mock TelephonyManager mTelephonyManager;
     @Mock NotificationManager mNotificationManager;
@@ -99,6 +102,17 @@
 
     NetworkNotificationManager mManager;
 
+
+    @BeforeClass
+    public static void setUpClass() {
+        Notification.DevFlags.sForceDefaults = true;
+    }
+
+    @AfterClass
+    public static void tearDownClass() {
+        Notification.DevFlags.sForceDefaults = false;
+    }
+
     @Before
     public void setUp() {
         MockitoAnnotations.initMocks(this);
@@ -109,6 +123,7 @@
         mCellNai.networkInfo = mNetworkInfo;
         mVpnNai.networkCapabilities = VPN_CAPABILITIES;
         mVpnNai.networkInfo = mNetworkInfo;
+        mDisplayMetrics.density = 2.275f;
         doReturn(true).when(mVpnNai).isVPN();
         when(mCtx.getResources()).thenReturn(mResources);
         when(mCtx.getPackageManager()).thenReturn(mPm);
@@ -120,6 +135,7 @@
                 .thenReturn(mNotificationManager);
         when(mNetworkInfo.getExtraInfo()).thenReturn(TEST_EXTRA_INFO);
         when(mResources.getColor(anyInt(), any())).thenReturn(0xFF607D8B);
+        when(mResources.getDisplayMetrics()).thenReturn(mDisplayMetrics);
 
         mManager = new NetworkNotificationManager(mCtx, mTelephonyManager);
     }
@@ -142,15 +158,15 @@
     public void testTitleOfPrivateDnsBroken() {
         // Test the title of mobile data.
         verifyTitleByNetwork(100, mCellNai, R.string.mobile_no_internet);
-        reset(mResources);
+        clearInvocations(mResources);
 
         // Test the title of wifi.
         verifyTitleByNetwork(101, mWifiNai, R.string.wifi_no_internet);
-        reset(mResources);
+        clearInvocations(mResources);
 
         // Test the title of other networks.
         verifyTitleByNetwork(102, mVpnNai, R.string.other_networks_no_internet);
-        reset(mResources);
+        clearInvocations(mResources);
     }
 
     @Test