diff --git a/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java b/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java
index 377da91..692a2dd 100644
--- a/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java
+++ b/Tethering/tests/integration/base/android/net/EthernetTetheringTestBase.java
@@ -31,12 +31,14 @@
 import static android.net.TetheringTester.isExpectedIcmpPacket;
 import static android.net.TetheringTester.isExpectedTcpPacket;
 import static android.net.TetheringTester.isExpectedUdpPacket;
+
 import static com.android.net.module.util.HexDump.dumpHexString;
 import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ROUTER_ADVERTISEMENT;
 import static com.android.net.module.util.NetworkStackConstants.TCPHDR_ACK;
 import static com.android.net.module.util.NetworkStackConstants.TCPHDR_SYN;
 import static com.android.testutils.TestNetworkTrackerKt.initTestNetwork;
 import static com.android.testutils.TestPermissionUtil.runAsShell;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
@@ -46,7 +48,6 @@
 import static org.junit.Assume.assumeFalse;
 import static org.junit.Assume.assumeTrue;
 
-import android.app.UiAutomation;
 import android.content.Context;
 import android.content.pm.PackageManager;
 import android.net.EthernetManager.TetheredInterfaceCallback;
@@ -141,11 +142,12 @@
     protected static final ByteBuffer TX_PAYLOAD =
             ByteBuffer.wrap(new byte[] { (byte) 0x56, (byte) 0x78 });
 
-    private final Context mContext = InstrumentationRegistry.getInstrumentation().getContext();
-    private final EthernetManager mEm = mContext.getSystemService(EthernetManager.class);
-    private final TetheringManager mTm = mContext.getSystemService(TetheringManager.class);
-    private final PackageManager mPackageManager = mContext.getPackageManager();
-    private final CtsNetUtils mCtsNetUtils = new CtsNetUtils(mContext);
+    private static final Context sContext =
+            InstrumentationRegistry.getInstrumentation().getContext();
+    private static final EthernetManager sEm = sContext.getSystemService(EthernetManager.class);
+    private static final TetheringManager sTm = sContext.getSystemService(TetheringManager.class);
+    private static final PackageManager sPackageManager = sContext.getPackageManager();
+    private static final CtsNetUtils sCtsNetUtils = new CtsNetUtils(sContext);
 
     // Late initialization in setUp()
     private boolean mRunTests;
@@ -161,7 +163,7 @@
     private MyTetheringEventCallback mTetheringEventCallback;
 
     public Context getContext() {
-        return mContext;
+        return sContext;
     }
 
     @BeforeClass
@@ -170,11 +172,10 @@
         // 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 CtsTetheringUtils utils = new CtsTetheringUtils(sContext);
         final TestTetheringEventCallback callback = utils.registerTetheringEventCallback();
         try {
-            if (!callback.isWifiTetheringSupported(ctx)) return;
+            if (!callback.isWifiTetheringSupported(sContext)) return;
 
             callback.expectNoTetheringActive();
 
@@ -195,13 +196,13 @@
         mRunTests = isEthernetTetheringSupported();
         assumeTrue(mRunTests);
 
-        mTetheredInterfaceRequester = new TetheredInterfaceRequester(mHandler, mEm);
+        mTetheredInterfaceRequester = new TetheredInterfaceRequester(mHandler);
     }
 
     private boolean isEthernetTetheringSupported() throws Exception {
-        if (mEm == null) return false;
+        if (sEm == null) return false;
 
-        return runAsShell(NETWORK_SETTINGS, TETHER_PRIVILEGED, () -> mTm.isTetheringSupported());
+        return runAsShell(NETWORK_SETTINGS, TETHER_PRIVILEGED, () -> sTm.isTetheringSupported());
     }
 
     protected void maybeStopTapPacketReader(final TapPacketReader tapPacketReader)
@@ -230,7 +231,7 @@
 
     protected void stopEthernetTethering(final MyTetheringEventCallback callback) {
         runAsShell(TETHER_PRIVILEGED, () -> {
-            mTm.stopTethering(TETHERING_ETHERNET);
+            sTm.stopTethering(TETHERING_ETHERNET);
             maybeUnregisterTetheringEventCallback(callback);
         });
     }
@@ -282,13 +283,13 @@
         // waiting timeout, just checking whether the system currently has any
         // ethernet interface is more reliable.
         if (!SdkLevel.isAtLeastT()) {
-            return runAsShell(CONNECTIVITY_USE_RESTRICTED_NETWORKS, () -> mEm.isAvailable());
+            return runAsShell(CONNECTIVITY_USE_RESTRICTED_NETWORKS, () -> sEm.isAvailable());
         }
 
         // If previous test case doesn't release tethering interface successfully, the other tests
         // after that test may be skipped as unexcepted.
         // TODO: figure out a better way to check default tethering interface existenion.
-        final TetheredInterfaceRequester requester = new TetheredInterfaceRequester(mHandler, mEm);
+        final TetheredInterfaceRequester requester = new TetheredInterfaceRequester(mHandler);
         try {
             // Use short timeout (200ms) for requesting an existing interface, if any, because
             // it should reurn faster than requesting a new tethering interface. Using default
@@ -308,13 +309,13 @@
 
     protected void setIncludeTestInterfaces(boolean include) {
         runAsShell(NETWORK_SETTINGS, () -> {
-            mEm.setIncludeTestInterfaces(include);
+            sEm.setIncludeTestInterfaces(include);
         });
     }
 
     protected void setPreferTestNetworks(boolean prefer) {
         runAsShell(NETWORK_SETTINGS, () -> {
-            mTm.setPreferTestNetworks(prefer);
+            sTm.setPreferTestNetworks(prefer);
         });
     }
 
@@ -344,7 +345,6 @@
 
 
     protected static final class MyTetheringEventCallback implements TetheringEventCallback {
-        private final TetheringManager mTm;
         private final CountDownLatch mTetheringStartedLatch = new CountDownLatch(1);
         private final CountDownLatch mTetheringStoppedLatch = new CountDownLatch(1);
         private final CountDownLatch mLocalOnlyStartedLatch = new CountDownLatch(1);
@@ -368,19 +368,18 @@
         // seconds. See b/289881008.
         private static final int EXPANDED_TIMEOUT_MS = 30000;
 
-        MyTetheringEventCallback(TetheringManager tm, String iface) {
-            this(tm, iface, null);
+        MyTetheringEventCallback(String iface) {
+            this(iface, null);
             mAcceptAnyUpstream = true;
         }
 
-        MyTetheringEventCallback(TetheringManager tm, String iface, Network expectedUpstream) {
-            mTm = tm;
+        MyTetheringEventCallback(String iface, Network expectedUpstream) {
             mIface = new TetheringInterface(TETHERING_ETHERNET, iface);
             mExpectedUpstream = expectedUpstream;
         }
 
         public void unregister() {
-            mTm.unregisterTetheringEventCallback(this);
+            sTm.unregisterTetheringEventCallback(this);
             mUnregistered = true;
         }
         @Override
@@ -531,12 +530,12 @@
         // after etherent tethering started.
         final MyTetheringEventCallback callback;
         if (expectedUpstream != null) {
-            callback = new MyTetheringEventCallback(mTm, iface, expectedUpstream);
+            callback = new MyTetheringEventCallback(iface, expectedUpstream);
         } else {
-            callback = new MyTetheringEventCallback(mTm, iface);
+            callback = new MyTetheringEventCallback(iface);
         }
         runAsShell(NETWORK_SETTINGS, () -> {
-            mTm.registerTetheringEventCallback(mHandler::post, callback);
+            sTm.registerTetheringEventCallback(mHandler::post, callback);
             // Need to hold the shell permission until callback is registered. This helps to avoid
             // the test become flaky.
             callback.awaitCallbackRegistered();
@@ -556,7 +555,7 @@
         };
         Log.d(TAG, "Starting Ethernet tethering");
         runAsShell(TETHER_PRIVILEGED, () -> {
-            mTm.startTethering(request, mHandler::post /* executor */, startTetheringCallback);
+            sTm.startTethering(request, mHandler::post /* executor */, startTetheringCallback);
             // Binder call is an async call. Need to hold the shell permission until tethering
             // started. This helps to avoid the test become flaky.
             if (!tetheringStartedLatch.await(TIMEOUT_MS, TimeUnit.MILLISECONDS)) {
@@ -606,14 +605,12 @@
 
     protected static final class TetheredInterfaceRequester implements TetheredInterfaceCallback {
         private final Handler mHandler;
-        private final EthernetManager mEm;
 
         private TetheredInterfaceRequest mRequest;
         private final CompletableFuture<String> mFuture = new CompletableFuture<>();
 
-        TetheredInterfaceRequester(Handler handler, EthernetManager em) {
+        TetheredInterfaceRequester(Handler handler) {
             mHandler = handler;
-            mEm = em;
         }
 
         @Override
@@ -631,7 +628,7 @@
             assertNull("BUG: more than one tethered interface request", mRequest);
             Log.d(TAG, "Requesting tethered interface");
             mRequest = runAsShell(NETWORK_SETTINGS, () ->
-                    mEm.requestTetheredInterface(mHandler::post, this));
+                    sEm.requestTetheredInterface(mHandler::post, this));
             return mFuture;
         }
 
@@ -654,7 +651,7 @@
 
     protected TestNetworkInterface createTestInterface() throws Exception {
         TestNetworkManager tnm = runAsShell(MANAGE_TEST_NETWORKS, () ->
-                mContext.getSystemService(TestNetworkManager.class));
+                sContext.getSystemService(TestNetworkManager.class));
         TestNetworkInterface iface = runAsShell(MANAGE_TEST_NETWORKS, () ->
                 tnm.createTapInterface());
         Log.d(TAG, "Created test interface " + iface.getInterfaceName());
@@ -669,7 +666,7 @@
         lp.setLinkAddresses(addresses);
         lp.setDnsServers(dnses);
 
-        return runAsShell(MANAGE_TEST_NETWORKS, () -> initTestNetwork(mContext, lp, TIMEOUT_MS));
+        return runAsShell(MANAGE_TEST_NETWORKS, () -> initTestNetwork(sContext, lp, TIMEOUT_MS));
     }
 
     protected void sendDownloadPacketUdp(@NonNull final InetAddress srcIp,
@@ -851,7 +848,7 @@
     private void maybeRetryTestedUpstreamChanged(final Network expectedUpstream,
             final TimeoutException fallbackException) throws Exception {
         // Fall back original exception because no way to reselect if there is no WIFI feature.
-        assertTrue(fallbackException.toString(), mPackageManager.hasSystemFeature(FEATURE_WIFI));
+        assertTrue(fallbackException.toString(), sPackageManager.hasSystemFeature(FEATURE_WIFI));
 
         // Try to toggle wifi network, if any, to reselect upstream network via default network
         // switching. Because test network has higher priority than internet network, this can
@@ -867,7 +864,7 @@
         // See Tethering#chooseUpstreamType, CtsNetUtils#toggleWifi.
         // TODO: toggle cellular network if the device has no WIFI feature.
         Log.d(TAG, "Toggle WIFI to retry upstream selection");
-        mCtsNetUtils.toggleWifi();
+        sCtsNetUtils.toggleWifi();
 
         // Wait for expected upstream.
         final CompletableFuture<Network> future = new CompletableFuture<>();
@@ -881,14 +878,14 @@
             }
         };
         try {
-            mTm.registerTetheringEventCallback(mHandler::post, callback);
+            sTm.registerTetheringEventCallback(mHandler::post, callback);
             assertEquals("onUpstreamChanged for unexpected network", expectedUpstream,
                     future.get(TIMEOUT_MS, TimeUnit.MILLISECONDS));
         } catch (TimeoutException e) {
             throw new AssertionError("Did not receive upstream " + expectedUpstream
                     + " callback after " + TIMEOUT_MS + "ms");
         } finally {
-            mTm.unregisterTetheringEventCallback(callback);
+            sTm.unregisterTetheringEventCallback(callback);
         }
     }
 
@@ -925,7 +922,7 @@
         mDownstreamReader = makePacketReader(mDownstreamIface);
         mUpstreamReader = makePacketReader(mUpstreamTracker.getTestIface());
 
-        final ConnectivityManager cm = mContext.getSystemService(ConnectivityManager.class);
+        final ConnectivityManager cm = sContext.getSystemService(ConnectivityManager.class);
         // Currently tethering don't have API to tell when ipv6 tethering is available. Thus, make
         // sure tethering already have ipv6 connectivity before testing.
         if (cm.getLinkProperties(mUpstreamTracker.getNetwork()).hasGlobalIpv6Address()) {