Add a keep connected for test reason

This has been sorely needed for a while. Instead of filing requests
for each of your networks in a CSTest, which is fiddly at best and
sometimes almost impossible (because you can't single out the network),
you can now add this flag and be done with it.

Test: CSKeepConnectedTest
Change-Id: Ie168fe1f3a17de035fdf05e3d6580d3262a3448e

tests/unit/java/com/android/server/connectivityservice/CSKeepConnectedTest.kt

@@ -0,0 +1,58 @@
+/*
+ * 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
+
+import android.net.NetworkRequest
+import android.net.NetworkScore
+import android.net.NetworkScore.KEEP_CONNECTED_FOR_TEST
+import android.os.Build
+import androidx.test.filters.SmallTest
+import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo
+import com.android.testutils.DevSdkIgnoreRunner
+import com.android.testutils.RecorderCallback.CallbackEntry.Lost
+import com.android.testutils.TestableNetworkCallback
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(DevSdkIgnoreRunner::class)
+@SmallTest
+@IgnoreUpTo(Build.VERSION_CODES.TIRAMISU)
+class CSKeepConnectedTest : CSTest() {
+    @Test
+    fun testKeepConnectedForTest() {
+        val keepAgent = Agent(score = FromS(NetworkScore.Builder()
+                .setKeepConnectedReason(KEEP_CONNECTED_FOR_TEST)
+                .build()))
+        val dontKeepAgent = Agent()
+        doTestKeepConnected(keepAgent, dontKeepAgent)
+    }
+
+    fun doTestKeepConnected(keepAgent: CSAgentWrapper, dontKeepAgent: CSAgentWrapper) {
+        val cb = TestableNetworkCallback()
+        cm.registerNetworkCallback(NetworkRequest.Builder().clearCapabilities().build(), cb)
+
+        keepAgent.connect()
+        dontKeepAgent.connect()
+
+        cb.expectAvailableCallbacks(keepAgent.network, validated = false)
+        cb.expectAvailableCallbacks(dontKeepAgent.network, validated = false)
+
+        // After the nascent timer, the agent without keep connected gets lost.
+        cb.expect<Lost>(dontKeepAgent.network)
+        cb.assertNoCallback()
+    }
+}

tests/unit/java/com/android/server/connectivityservice/base/CSAgentWrapper.kt

@@ -129,9 +129,10 @@ class CSAgentWrapper(
 
     fun connect() {
         val mgr = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
-        val request = NetworkRequest.Builder().clearCapabilities()
-                .addTransportType(nc.transportTypes[0])
-                .build()
+        val request = NetworkRequest.Builder().apply {
+            clearCapabilities()
+            if (nc.transportTypes.isNotEmpty()) addTransportType(nc.transportTypes[0])
+        }.build()
         val cb = TestableNetworkCallback()
         mgr.registerNetworkCallback(request, cb)
         agent.markConnected()