diff --git a/service-t/src/com/android/server/connectivity/mdns/MdnsReplySender.java b/service-t/src/com/android/server/connectivity/mdns/MdnsReplySender.java
index ea3af5e..651b643 100644
--- a/service-t/src/com/android/server/connectivity/mdns/MdnsReplySender.java
+++ b/service-t/src/com/android/server/connectivity/mdns/MdnsReplySender.java
@@ -25,6 +25,7 @@
 import android.os.Looper;
 import android.os.Message;
 
+import com.android.internal.annotations.VisibleForTesting;
 import com.android.net.module.util.SharedLog;
 import com.android.server.connectivity.mdns.util.MdnsUtils;
 
@@ -57,15 +58,46 @@
     @NonNull
     private final SharedLog mSharedLog;
     private final boolean mEnableDebugLog;
+    @NonNull
+    private final Dependencies mDependencies;
+
+    /**
+     * Dependencies of MdnsReplySender, for injection in tests.
+     */
+    @VisibleForTesting
+    public static class Dependencies {
+        /**
+         * @see Handler#sendMessageDelayed(Message, long)
+         */
+        public void sendMessageDelayed(@NonNull Handler handler, @NonNull Message message,
+                long delayMillis) {
+            handler.sendMessageDelayed(message, delayMillis);
+        }
+
+        /**
+         * @see Handler#removeMessages(int)
+         */
+        public void removeMessages(@NonNull Handler handler, int what) {
+            handler.removeMessages(what);
+        }
+    }
 
     public MdnsReplySender(@NonNull Looper looper, @NonNull MdnsInterfaceSocket socket,
             @NonNull byte[] packetCreationBuffer, @NonNull SharedLog sharedLog,
             boolean enableDebugLog) {
+        this(looper, socket, packetCreationBuffer, sharedLog, enableDebugLog, new Dependencies());
+    }
+
+    @VisibleForTesting
+    public MdnsReplySender(@NonNull Looper looper, @NonNull MdnsInterfaceSocket socket,
+            @NonNull byte[] packetCreationBuffer, @NonNull SharedLog sharedLog,
+            boolean enableDebugLog, @NonNull Dependencies dependencies) {
         mHandler = new SendHandler(looper);
         mSocket = socket;
         mPacketCreationBuffer = packetCreationBuffer;
         mSharedLog = sharedLog;
         mEnableDebugLog = enableDebugLog;
+        mDependencies = dependencies;
     }
 
     /**
@@ -74,7 +106,8 @@
     public void queueReply(@NonNull MdnsReplyInfo reply) {
         ensureRunningOnHandlerThread(mHandler);
         // TODO: implement response aggregation (RFC 6762 6.4)
-        mHandler.sendMessageDelayed(mHandler.obtainMessage(MSG_SEND, reply), reply.sendDelayMs);
+        mDependencies.sendMessageDelayed(
+                mHandler, mHandler.obtainMessage(MSG_SEND, reply), reply.sendDelayMs);
 
         if (mEnableDebugLog) {
             mSharedLog.v("Scheduling " + reply);
@@ -104,7 +137,7 @@
      */
     public void cancelAll() {
         ensureRunningOnHandlerThread(mHandler);
-        mHandler.removeMessages(MSG_SEND);
+        mDependencies.removeMessages(mHandler, MSG_SEND);
     }
 
     private class SendHandler extends Handler {
diff --git a/tests/unit/java/com/android/server/connectivity/mdns/MdnsReplySenderTest.kt b/tests/unit/java/com/android/server/connectivity/mdns/MdnsReplySenderTest.kt
new file mode 100644
index 0000000..9e2933f
--- /dev/null
+++ b/tests/unit/java/com/android/server/connectivity/mdns/MdnsReplySenderTest.kt
@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2023 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 com.android.server.connectivity.mdns
+
+import android.net.InetAddresses
+import android.net.LinkAddress
+import android.os.Build
+import android.os.Handler
+import android.os.HandlerThread
+import android.os.Message
+import com.android.net.module.util.SharedLog
+import com.android.server.connectivity.mdns.MdnsConstants.IPV4_SOCKET_ADDR
+import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo
+import com.android.testutils.DevSdkIgnoreRunner
+import java.net.InetSocketAddress
+import java.util.concurrent.CompletableFuture
+import java.util.concurrent.TimeUnit
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.ArgumentCaptor
+import org.mockito.Mockito.argThat
+import org.mockito.Mockito.doReturn
+import org.mockito.Mockito.eq
+import org.mockito.Mockito.mock
+import org.mockito.Mockito.timeout
+import org.mockito.Mockito.verify
+
+private const val TEST_PORT = 12345
+private const val DEFAULT_TIMEOUT_MS = 2000L
+private const val LONG_TTL = 4_500_000L
+private const val SHORT_TTL = 120_000L
+
+@RunWith(DevSdkIgnoreRunner::class)
+@IgnoreUpTo(Build.VERSION_CODES.S_V2)
+class MdnsReplySenderTest {
+    private val serviceName = arrayOf("MyTestService", "_testservice", "_tcp", "local")
+    private val serviceType = arrayOf("_testservice", "_tcp", "local")
+    private val hostname = arrayOf("Android_000102030405060708090A0B0C0D0E0F", "local")
+    private val hostAddresses = listOf(
+            LinkAddress(InetAddresses.parseNumericAddress("192.0.2.111"), 24),
+            LinkAddress(InetAddresses.parseNumericAddress("2001:db8::111"), 64),
+            LinkAddress(InetAddresses.parseNumericAddress("2001:db8::222"), 64))
+    private val answers = listOf(
+            MdnsPointerRecord(serviceType, 0L /* receiptTimeMillis */, false /* cacheFlush */,
+                    LONG_TTL, serviceName))
+    private val additionalAnswers = listOf(
+            MdnsTextRecord(serviceName, 0L /* receiptTimeMillis */, true /* cacheFlush */, LONG_TTL,
+                    listOf() /* entries */),
+            MdnsServiceRecord(serviceName, 0L /* receiptTimeMillis */, true /* cacheFlush */,
+                    SHORT_TTL, 0 /* servicePriority */, 0 /* serviceWeight */, TEST_PORT, hostname),
+            MdnsInetAddressRecord(hostname, 0L /* receiptTimeMillis */, true /* cacheFlush */,
+                    SHORT_TTL, hostAddresses[0].address),
+            MdnsInetAddressRecord(hostname, 0L /* receiptTimeMillis */, true /* cacheFlush */,
+                    SHORT_TTL, hostAddresses[1].address),
+            MdnsInetAddressRecord(hostname, 0L /* receiptTimeMillis */, true /* cacheFlush */,
+                    SHORT_TTL, hostAddresses[2].address),
+            MdnsNsecRecord(serviceName, 0L /* receiptTimeMillis */, true /* cacheFlush */, LONG_TTL,
+                    serviceName /* nextDomain */,
+                    intArrayOf(MdnsRecord.TYPE_TXT, MdnsRecord.TYPE_SRV)),
+            MdnsNsecRecord(hostname, 0L /* receiptTimeMillis */, true /* cacheFlush */, SHORT_TTL,
+                    hostname /* nextDomain */, intArrayOf(MdnsRecord.TYPE_A, MdnsRecord.TYPE_AAAA)))
+    private val thread = HandlerThread(MdnsReplySenderTest::class.simpleName)
+    private val socket = mock(MdnsInterfaceSocket::class.java)
+    private val buffer = ByteArray(1500)
+    private val sharedLog = SharedLog(MdnsReplySenderTest::class.simpleName)
+    private val deps = mock(MdnsReplySender.Dependencies::class.java)
+    private val handler by lazy { Handler(thread.looper) }
+    private val replySender by lazy {
+        MdnsReplySender(thread.looper, socket, buffer, sharedLog, false /* enableDebugLog */, deps)
+    }
+
+    @Before
+    fun setUp() {
+        thread.start()
+        doReturn(true).`when`(socket).hasJoinedIpv4()
+        doReturn(true).`when`(socket).hasJoinedIpv6()
+    }
+
+    @After
+    fun tearDown() {
+        thread.quitSafely()
+        thread.join()
+    }
+
+    private fun <T> runningOnHandlerAndReturn(functor: (() -> T)): T {
+        val future = CompletableFuture<T>()
+        handler.post {
+            future.complete(functor())
+        }
+        return future.get(DEFAULT_TIMEOUT_MS, TimeUnit.MILLISECONDS)
+    }
+
+    private fun sendNow(packet: MdnsPacket, destination: InetSocketAddress):
+            Unit = runningOnHandlerAndReturn { replySender.sendNow(packet, destination) }
+
+    private fun queueReply(reply: MdnsReplyInfo):
+            Unit = runningOnHandlerAndReturn { replySender.queueReply(reply) }
+
+    @Test
+    fun testSendNow() {
+        val packet = MdnsPacket(0x8400,
+                listOf() /* questions */,
+                answers,
+                listOf() /* authorityRecords */,
+                additionalAnswers)
+        sendNow(packet, IPV4_SOCKET_ADDR)
+        verify(socket).send(argThat{ it.socketAddress.equals(IPV4_SOCKET_ADDR) })
+    }
+
+    @Test
+    fun testQueueReply() {
+        val reply = MdnsReplyInfo(answers, additionalAnswers, 20L /* sendDelayMs */,
+                IPV4_SOCKET_ADDR)
+        val handlerCaptor = ArgumentCaptor.forClass(Handler::class.java)
+        val messageCaptor = ArgumentCaptor.forClass(Message::class.java)
+        queueReply(reply)
+        verify(deps).sendMessageDelayed(handlerCaptor.capture(), messageCaptor.capture(), eq(20L))
+
+        val realHandler = handlerCaptor.value
+        val delayMessage = messageCaptor.value
+        realHandler.sendMessage(delayMessage)
+        verify(socket, timeout(DEFAULT_TIMEOUT_MS)).send(argThat{
+            it.socketAddress.equals(IPV4_SOCKET_ADDR)
+        })
+    }
+}