Add mulit devices mdns tests

Add tests to verify mdns advertising, discovery, and resolution
over a hotspot connection using multiple devices.

Bug: 343311941
Test: atest CtsConnectivityMultiDevicesTestCases
Change-Id: I9f52a271385cddc12c8f57b188e080ad69651f9f
diff --git a/tests/cts/multidevices/snippet/Android.bp b/tests/cts/multidevices/snippet/Android.bp
index 5940cbb..b0b32c2 100644
--- a/tests/cts/multidevices/snippet/Android.bp
+++ b/tests/cts/multidevices/snippet/Android.bp
@@ -25,6 +25,7 @@
     ],
     srcs: [
         "ConnectivityMultiDevicesSnippet.kt",
+        "MdnsMultiDevicesSnippet.kt",
     ],
     manifest: "AndroidManifest.xml",
     static_libs: [
diff --git a/tests/cts/multidevices/snippet/AndroidManifest.xml b/tests/cts/multidevices/snippet/AndroidManifest.xml
index 9ed8146..967e581 100644
--- a/tests/cts/multidevices/snippet/AndroidManifest.xml
+++ b/tests/cts/multidevices/snippet/AndroidManifest.xml
@@ -27,7 +27,8 @@
          of a snippet class -->
     <meta-data
         android:name="mobly-snippets"
-        android:value="com.google.snippet.connectivity.ConnectivityMultiDevicesSnippet" />
+        android:value="com.google.snippet.connectivity.ConnectivityMultiDevicesSnippet,
+                       com.google.snippet.connectivity.MdnsMultiDevicesSnippet" />
   </application>
   <!-- Add an instrumentation tag so that the app can be launched through an
        instrument command. The runner `com.google.android.mobly.snippet.SnippetRunner`
diff --git a/tests/cts/multidevices/snippet/MdnsMultiDevicesSnippet.kt b/tests/cts/multidevices/snippet/MdnsMultiDevicesSnippet.kt
new file mode 100644
index 0000000..1b288df
--- /dev/null
+++ b/tests/cts/multidevices/snippet/MdnsMultiDevicesSnippet.kt
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2024 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.google.snippet.connectivity
+
+import android.net.nsd.NsdManager
+import android.net.nsd.NsdServiceInfo
+import androidx.test.platform.app.InstrumentationRegistry
+import com.android.testutils.NsdDiscoveryRecord
+import com.android.testutils.NsdDiscoveryRecord.DiscoveryEvent.DiscoveryStopped
+import com.android.testutils.NsdRegistrationRecord
+import com.android.testutils.NsdRegistrationRecord.RegistrationEvent.ServiceRegistered
+import com.android.testutils.NsdRegistrationRecord.RegistrationEvent.ServiceUnregistered
+import com.android.testutils.NsdResolveRecord
+import com.android.testutils.NsdResolveRecord.ResolveEvent.ServiceResolved
+import com.google.android.mobly.snippet.Snippet
+import com.google.android.mobly.snippet.rpc.Rpc
+import kotlin.test.assertEquals
+import org.junit.Assert.assertArrayEquals
+
+private const val SERVICE_NAME = "MultiDevicesTest"
+private const val SERVICE_TYPE = "_multi_devices._tcp"
+private const val SERVICE_ATTRIBUTES_KEY = "key"
+private const val SERVICE_ATTRIBUTES_VALUE = "value"
+private const val SERVICE_PORT = 12345
+private const val REGISTRATION_TIMEOUT_MS = 10_000L
+
+class MdnsMultiDevicesSnippet : Snippet {
+    private val context = InstrumentationRegistry.getInstrumentation().getTargetContext()
+    private val nsdManager = context.getSystemService(NsdManager::class.java)!!
+    private val registrationRecord = NsdRegistrationRecord()
+    private val discoveryRecord = NsdDiscoveryRecord()
+    private val resolveRecord = NsdResolveRecord()
+
+    @Rpc(description = "Register a mDns service")
+    fun registerMDnsService() {
+        val info = NsdServiceInfo()
+        info.setServiceName(SERVICE_NAME)
+        info.setServiceType(SERVICE_TYPE)
+        info.setPort(SERVICE_PORT)
+        info.setAttribute(SERVICE_ATTRIBUTES_KEY, SERVICE_ATTRIBUTES_VALUE)
+        nsdManager.registerService(info, NsdManager.PROTOCOL_DNS_SD, registrationRecord)
+        registrationRecord.expectCallback<ServiceRegistered>(REGISTRATION_TIMEOUT_MS)
+    }
+
+    @Rpc(description = "Unregister a mDns service")
+    fun unregisterMDnsService() {
+        nsdManager.unregisterService(registrationRecord)
+        registrationRecord.expectCallback<ServiceUnregistered>()
+    }
+
+    @Rpc(description = "Ensure the discovery and resolution of the mDNS service")
+    // Suppress the warning, as the NsdManager#resolveService() method is deprecated.
+    @Suppress("DEPRECATION")
+    fun ensureMDnsServiceDiscoveryAndResolution() {
+        // Discover a mDns service that matches the test service
+        nsdManager.discoverServices(SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, discoveryRecord)
+        val info = discoveryRecord.waitForServiceDiscovered(SERVICE_NAME, SERVICE_TYPE)
+        // Resolve the retrieved mDns service.
+        nsdManager.resolveService(info, resolveRecord)
+        val serviceResolved = resolveRecord.expectCallbackEventually<ServiceResolved>()
+        serviceResolved.serviceInfo.let {
+            assertEquals(SERVICE_NAME, it.serviceName)
+            assertEquals(".$SERVICE_TYPE", it.serviceType)
+            assertEquals(SERVICE_PORT, it.port)
+            assertEquals(1, it.attributes.size)
+            assertArrayEquals(
+                    SERVICE_ATTRIBUTES_VALUE.encodeToByteArray(),
+                    it.attributes[SERVICE_ATTRIBUTES_KEY]
+            )
+        }
+    }
+
+    @Rpc(description = "Stop discovery")
+    fun stopMDnsServiceDiscovery() {
+        nsdManager.stopServiceDiscovery(discoveryRecord)
+        discoveryRecord.expectCallbackEventually<DiscoveryStopped>()
+    }
+}