Add ConnectivityServiceIntegrationTest

This test exercises the Connectivity <-> NetworkMonitor integration.
This CL only contains a simple test (network validates), but more
generally it sets up a test package that contains both services.jar
classes and NetworkStack classes, and runs NetworkStack components in
another process (using TestNetworkStackService).

ConnectivityServiceIntegrationTest runs in the test process and binds to
TestNetworkStackService to obtain TestNetworkStackConnector and to
NetworkStackInstrumentationService to obtain
NetworkStackInstrumentationConnector. That last connector allows the
test to mock NetworkMonitor HTTP Requests.

Test: atest FrameworksNetIntegrationTests
Change-Id: Ieca18e273609044cf6b1870d2f0dba33ca7b38d3
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index d822879..6a6a300 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -2164,7 +2164,11 @@
         }
     }
 
-    void systemReady() {
+    /**
+     * Called when the system is ready and ConnectivityService can initialize remaining components.
+     */
+    @VisibleForTesting
+    public void systemReady() {
         mProxyTracker.loadGlobalProxy();
         registerNetdEventCallback();
         mTethering.systemReady();
diff --git a/tests/net/integration/AndroidManifest.xml b/tests/net/integration/AndroidManifest.xml
new file mode 100644
index 0000000..91b3cd9
--- /dev/null
+++ b/tests/net/integration/AndroidManifest.xml
@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+ * Copyright (C) 2019 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.
+ */
+-->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          xmlns:tools="http://schemas.android.com/tools"
+          package="com.android.server.net.integrationtests">
+
+    <!-- For ConnectivityService registerReceiverAsUser (receiving broadcasts) -->
+    <uses-permission android:name="android.permission.INTERACT_ACROSS_USERS_FULL" />
+    <!-- PermissionMonitor sets network permissions for each user -->
+    <uses-permission android:name="android.permission.MANAGE_USERS" />
+    <!-- ConnectivityService sends notifications to BatteryStats -->
+    <uses-permission android:name="android.permission.UPDATE_DEVICE_STATS" />
+    <application android:debuggable="true">
+        <uses-library android:name="android.test.runner" />
+
+        <!-- This manifest is merged with the base manifest of the real NetworkStack app.
+             Remove the NetworkStackService from the base (real) manifest, and replace with a test
+             service that responds to the same intent -->
+        <service android:name="com.android.server.NetworkStackService" tools:node="remove"/>
+        <service android:name=".TestNetworkStackService"
+                 android:process="com.android.server.net.integrationtests.testnetworkstack">
+            <intent-filter>
+                <action android:name="android.net.INetworkStackConnector.Test"/>
+            </intent-filter>
+        </service>
+        <service android:name=".NetworkStackInstrumentationService"
+                 android:process="com.android.server.net.integrationtests.testnetworkstack">
+            <intent-filter>
+                <action android:name=".INetworkStackInstrumentation"/>
+            </intent-filter>
+        </service>
+        <service tools:replace="android:process"
+                 android:name="com.android.server.connectivity.ipmemorystore.RegularMaintenanceJobService"
+                 android:process="com.android.server.net.integrationtests.testnetworkstack"/>
+
+    </application>
+
+    <instrumentation android:name="androidx.test.runner.AndroidJUnitRunner"
+                     android:targetPackage="com.android.server.net.integrationtests"
+                     android:label="Frameworks Net Integration Tests" />
+
+</manifest>
diff --git a/tests/net/integration/res/values/config.xml b/tests/net/integration/res/values/config.xml
new file mode 100644
index 0000000..2c8046f
--- /dev/null
+++ b/tests/net/integration/res/values/config.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!--
+    Override configuration for testing. The below settings use the config_ variants, which are
+    normally used by RROs to override the setting with highest priority. -->
+    <integer name="config_captive_portal_dns_probe_timeout">12500</integer>
+    <string name="config_captive_portal_http_url" translatable="false">http://test.android.com</string>
+    <string name="config_captive_portal_https_url" translatable="false">https://secure.test.android.com</string>
+    <string-array name="config_captive_portal_fallback_urls" translatable="false">
+        <item>http://fallback1.android.com</item>
+        <item>http://fallback2.android.com</item>
+    </string-array>
+    <string-array name="config_captive_portal_fallback_probe_specs" translatable="false">
+    </string-array>
+</resources>
diff --git a/tests/net/integration/src/android/net/TestNetworkStackClient.kt b/tests/net/integration/src/android/net/TestNetworkStackClient.kt
new file mode 100644
index 0000000..01eb514
--- /dev/null
+++ b/tests/net/integration/src/android/net/TestNetworkStackClient.kt
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2019 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.content.ComponentName
+import android.content.Context
+import android.content.Intent
+import android.os.IBinder
+import com.android.server.net.integrationtests.TestNetworkStackService
+import org.mockito.Mockito.any
+import org.mockito.Mockito.spy
+import org.mockito.Mockito.timeout
+import org.mockito.Mockito.verify
+import kotlin.test.fail
+
+const val TEST_ACTION_SUFFIX = ".Test"
+
+class TestNetworkStackClient(context: Context) : NetworkStackClient(TestDependencies(context)) {
+    // TODO: consider switching to TrackRecord for more expressive checks
+    private val lastCallbacks = HashMap<Network, INetworkMonitorCallbacks>()
+
+    private class TestDependencies(private val context: Context) : Dependencies {
+        override fun addToServiceManager(service: IBinder) = Unit
+        override fun checkCallerUid() = Unit
+
+        override fun getConnectivityModuleConnector(): ConnectivityModuleConnector {
+            return ConnectivityModuleConnector { _, _, _, inSystemProcess ->
+                getNetworkStackIntent(inSystemProcess)
+            }.also { it.init(context) }
+        }
+
+        private fun getNetworkStackIntent(inSystemProcess: Boolean): Intent? {
+            // Simulate out-of-system-process config: in-process service not found (null intent)
+            if (inSystemProcess) return null
+            val intent = Intent(INetworkStackConnector::class.qualifiedName + TEST_ACTION_SUFFIX)
+            val serviceName = TestNetworkStackService::class.qualifiedName
+                    ?: fail("TestNetworkStackService name not found")
+            intent.component = ComponentName(context.packageName, serviceName)
+            return intent
+        }
+    }
+
+    // base may be an instance of an inaccessible subclass, so non-spyable.
+    // Use a known open class that delegates to the original instance for all methods except
+    // asBinder. asBinder needs to use its own non-delegated implementation as otherwise it would
+    // return a binder token to a class that is not spied on.
+    open class NetworkMonitorCallbacksWrapper(private val base: INetworkMonitorCallbacks) :
+            INetworkMonitorCallbacks.Stub(), INetworkMonitorCallbacks by base {
+        // asBinder is implemented by both base class and delegate: specify explicitly
+        override fun asBinder(): IBinder {
+            return super.asBinder()
+        }
+    }
+
+    override fun makeNetworkMonitor(network: Network, name: String?, cb: INetworkMonitorCallbacks) {
+        val cbSpy = spy(NetworkMonitorCallbacksWrapper(cb))
+        lastCallbacks[network] = cbSpy
+        super.makeNetworkMonitor(network, name, cbSpy)
+    }
+
+    fun verifyNetworkMonitorCreated(network: Network, timeoutMs: Long) {
+        val cb = lastCallbacks[network]
+                ?: fail("NetworkMonitor for network $network not requested")
+        verify(cb, timeout(timeoutMs)).onNetworkMonitorCreated(any())
+    }
+}
\ No newline at end of file
diff --git a/tests/net/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt b/tests/net/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt
new file mode 100644
index 0000000..334b26d
--- /dev/null
+++ b/tests/net/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt
@@ -0,0 +1,210 @@
+/*
+ * Copyright (C) 2019 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.net.integrationtests
+
+import android.content.ComponentName
+import android.content.Context
+import android.content.Context.BIND_AUTO_CREATE
+import android.content.Context.BIND_IMPORTANT
+import android.content.Intent
+import android.content.ServiceConnection
+import android.net.ConnectivityManager
+import android.net.IDnsResolver
+import android.net.INetd
+import android.net.INetworkPolicyManager
+import android.net.INetworkStatsService
+import android.net.LinkProperties
+import android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET
+import android.net.NetworkCapabilities.TRANSPORT_CELLULAR
+import android.net.NetworkRequest
+import android.net.TestNetworkStackClient
+import android.net.metrics.IpConnectivityLog
+import android.os.ConditionVariable
+import android.os.IBinder
+import android.os.INetworkManagementService
+import android.testing.TestableContext
+import android.util.Log
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
+import com.android.server.ConnectivityService
+import com.android.server.LocalServices
+import com.android.server.NetworkAgentWrapper
+import com.android.server.TestNetIdManager
+import com.android.server.connectivity.DefaultNetworkMetrics
+import com.android.server.connectivity.IpConnectivityMetrics
+import com.android.server.connectivity.MockableSystemProperties
+import com.android.server.connectivity.ProxyTracker
+import com.android.server.connectivity.Tethering
+import com.android.server.net.NetworkPolicyManagerInternal
+import com.android.testutils.TestableNetworkCallback
+import org.junit.After
+import org.junit.Before
+import org.junit.BeforeClass
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Mock
+import org.mockito.Mockito.any
+import org.mockito.Mockito.doNothing
+import org.mockito.Mockito.doReturn
+import org.mockito.Mockito.mock
+import org.mockito.Mockito.spy
+import org.mockito.MockitoAnnotations
+import org.mockito.Spy
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+import kotlin.test.fail
+
+const val SERVICE_BIND_TIMEOUT_MS = 5_000L
+const val TEST_TIMEOUT_MS = 1_000L
+
+/**
+ * Test that exercises an instrumented version of ConnectivityService against an instrumented
+ * NetworkStack in a different test process.
+ */
+@RunWith(AndroidJUnit4::class)
+class ConnectivityServiceIntegrationTest {
+    // lateinit used here for mocks as they need to be reinitialized between each test and the test
+    // should crash if they are used before being initialized.
+    @Mock
+    private lateinit var netManager: INetworkManagementService
+    @Mock
+    private lateinit var statsService: INetworkStatsService
+    @Mock
+    private lateinit var policyManager: INetworkPolicyManager
+    @Mock
+    private lateinit var log: IpConnectivityLog
+    @Mock
+    private lateinit var netd: INetd
+    @Mock
+    private lateinit var dnsResolver: IDnsResolver
+    @Mock
+    private lateinit var metricsLogger: IpConnectivityMetrics.Logger
+    @Mock
+    private lateinit var defaultMetrics: DefaultNetworkMetrics
+    @Spy
+    private var context = TestableContext(realContext)
+
+    // lateinit for these three classes under test, as they should be reset to a different instance
+    // for every test but should always be initialized before use (or the test should crash).
+    private lateinit var networkStackClient: TestNetworkStackClient
+    private lateinit var service: ConnectivityService
+    private lateinit var cm: ConnectivityManager
+
+    companion object {
+        // lateinit for this binder token, as it must be initialized before any test code is run
+        // and use of it before init should crash the test.
+        private lateinit var nsInstrumentation: INetworkStackInstrumentation
+        private val bindingCondition = ConditionVariable(false)
+
+        private val realContext get() = InstrumentationRegistry.getInstrumentation().context
+
+        private class InstrumentationServiceConnection : ServiceConnection {
+            override fun onServiceConnected(name: ComponentName?, service: IBinder?) {
+                Log.i("TestNetworkStack", "Service connected")
+                try {
+                    if (service == null) fail("Error binding to NetworkStack instrumentation")
+                    if (::nsInstrumentation.isInitialized) fail("Service already connected")
+                    nsInstrumentation = INetworkStackInstrumentation.Stub.asInterface(service)
+                } finally {
+                    bindingCondition.open()
+                }
+            }
+
+            override fun onServiceDisconnected(name: ComponentName?) = Unit
+        }
+
+        @BeforeClass
+        @JvmStatic
+        fun setUpClass() {
+            val intent = Intent(realContext, NetworkStackInstrumentationService::class.java)
+            intent.action = INetworkStackInstrumentation::class.qualifiedName
+            assertTrue(realContext.bindService(intent, InstrumentationServiceConnection(),
+                    BIND_AUTO_CREATE or BIND_IMPORTANT),
+                    "Error binding to instrumentation service")
+            assertTrue(bindingCondition.block(SERVICE_BIND_TIMEOUT_MS),
+                    "Timed out binding to instrumentation service " +
+                            "after $SERVICE_BIND_TIMEOUT_MS ms")
+        }
+    }
+
+    @Before
+    fun setUp() {
+        MockitoAnnotations.initMocks(this)
+        doReturn(defaultMetrics).`when`(metricsLogger).defaultNetworkMetrics()
+        doNothing().`when`(context).sendStickyBroadcastAsUser(any(), any(), any())
+
+        networkStackClient = TestNetworkStackClient(realContext)
+        networkStackClient.init()
+        networkStackClient.start()
+
+        LocalServices.removeServiceForTest(NetworkPolicyManagerInternal::class.java)
+        LocalServices.addService(NetworkPolicyManagerInternal::class.java,
+                mock(NetworkPolicyManagerInternal::class.java))
+
+        service = TestConnectivityService(makeDependencies())
+        cm = ConnectivityManager(context, service)
+        context.addMockSystemService(Context.CONNECTIVITY_SERVICE, cm)
+
+        service.systemReady()
+    }
+
+    private inner class TestConnectivityService(deps: Dependencies) : ConnectivityService(
+            context, netManager, statsService, policyManager, dnsResolver, log, netd, deps)
+
+    private fun makeDependencies(): ConnectivityService.Dependencies {
+        val deps = spy(ConnectivityService.Dependencies())
+        doReturn(networkStackClient).`when`(deps).networkStack
+        doReturn(metricsLogger).`when`(deps).metricsLogger
+        doReturn(mock(Tethering::class.java)).`when`(deps).makeTethering(
+                any(), any(), any(), any(), any())
+        doReturn(mock(ProxyTracker::class.java)).`when`(deps).makeProxyTracker(any(), any())
+        doReturn(mock(MockableSystemProperties::class.java)).`when`(deps).systemProperties
+        doReturn(TestNetIdManager()).`when`(deps).makeNetIdManager()
+        return deps
+    }
+
+    @After
+    fun tearDown() {
+        nsInstrumentation.clearAllState()
+    }
+
+    @Test
+    fun testValidation() {
+        val request = NetworkRequest.Builder()
+                .clearCapabilities()
+                .addCapability(NET_CAPABILITY_INTERNET)
+                .build()
+        val testCallback = TestableNetworkCallback()
+
+        cm.registerNetworkCallback(request, testCallback)
+        nsInstrumentation.addHttpResponse(HttpResponse(
+                "http://test.android.com",
+                responseCode = 204, contentLength = 42, redirectUrl = null))
+        nsInstrumentation.addHttpResponse(HttpResponse(
+                "https://secure.test.android.com",
+                responseCode = 204, contentLength = 42, redirectUrl = null))
+
+        val na = NetworkAgentWrapper(TRANSPORT_CELLULAR, LinkProperties(), context)
+        networkStackClient.verifyNetworkMonitorCreated(na.network, TEST_TIMEOUT_MS)
+
+        na.addCapability(NET_CAPABILITY_INTERNET)
+        na.connect()
+
+        testCallback.expectAvailableThenValidatedCallbacks(na.network, TEST_TIMEOUT_MS)
+        assertEquals(2, nsInstrumentation.getRequestUrls().size)
+    }
+}
\ No newline at end of file
diff --git a/tests/net/integration/src/com/android/server/net/integrationtests/HttpResponse.kt b/tests/net/integration/src/com/android/server/net/integrationtests/HttpResponse.kt
new file mode 100644
index 0000000..45073d8
--- /dev/null
+++ b/tests/net/integration/src/com/android/server/net/integrationtests/HttpResponse.kt
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2019 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.net.integrationtests
+
+import android.os.Parcel
+import android.os.Parcelable
+
+data class HttpResponse(
+    val requestUrl: String,
+    val responseCode: Int,
+    val contentLength: Long,
+    val redirectUrl: String?
+) : Parcelable {
+    constructor(p: Parcel): this(p.readString(), p.readInt(), p.readLong(), p.readString())
+
+    override fun writeToParcel(dest: Parcel, flags: Int) {
+        with(dest) {
+            writeString(requestUrl)
+            writeInt(responseCode)
+            writeLong(contentLength)
+            writeString(redirectUrl)
+        }
+    }
+
+    override fun describeContents() = 0
+    companion object CREATOR : Parcelable.Creator<HttpResponse> {
+        override fun createFromParcel(source: Parcel) = HttpResponse(source)
+        override fun newArray(size: Int) = arrayOfNulls<HttpResponse?>(size)
+    }
+}
\ No newline at end of file
diff --git a/tests/net/integration/src/com/android/server/net/integrationtests/NetworkStackInstrumentationService.kt b/tests/net/integration/src/com/android/server/net/integrationtests/NetworkStackInstrumentationService.kt
new file mode 100644
index 0000000..4827d29
--- /dev/null
+++ b/tests/net/integration/src/com/android/server/net/integrationtests/NetworkStackInstrumentationService.kt
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2019 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.net.integrationtests
+
+import android.app.Service
+import android.content.Intent
+import java.net.URL
+import java.util.Collections
+import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.ConcurrentLinkedQueue
+import kotlin.collections.ArrayList
+import kotlin.test.fail
+
+/**
+ * An instrumentation interface for the NetworkStack that allows controlling behavior to
+ * facilitate integration tests.
+ */
+class NetworkStackInstrumentationService : Service() {
+    override fun onBind(intent: Intent) = InstrumentationConnector.asBinder()
+
+    object InstrumentationConnector : INetworkStackInstrumentation.Stub() {
+        private val httpResponses = ConcurrentHashMap<String, ConcurrentLinkedQueue<HttpResponse>>()
+                .run {
+                    withDefault { key -> getOrPut(key) { ConcurrentLinkedQueue() } }
+                }
+        private val httpRequestUrls = Collections.synchronizedList(ArrayList<String>())
+
+        /**
+         * Called when an HTTP request is being processed by NetworkMonitor. Returns the response
+         * that should be simulated.
+         */
+        fun processRequest(url: URL): HttpResponse {
+            val strUrl = url.toString()
+            httpRequestUrls.add(strUrl)
+            return httpResponses[strUrl]?.poll()
+                    ?: fail("No mocked response for request: $strUrl. " +
+                            "Mocked URL keys are: ${httpResponses.keys}")
+        }
+
+        /**
+         * Clear all state of this connector. This is intended for use between two tests, so all
+         * state should be reset as if the connector was just created.
+         */
+        override fun clearAllState() {
+            httpResponses.clear()
+            httpRequestUrls.clear()
+        }
+
+        /**
+         * Add a response to a future HTTP request.
+         *
+         * <p>For any subsequent HTTP/HTTPS query, the first response with a matching URL will be
+         * used to mock the query response.
+         */
+        override fun addHttpResponse(response: HttpResponse) {
+            httpResponses.getValue(response.requestUrl).add(response)
+        }
+
+        /**
+         * Get the ordered list of request URLs that have been sent by NetworkMonitor, and were
+         * answered based on mock responses.
+         */
+        override fun getRequestUrls(): List<String> {
+            return ArrayList(httpRequestUrls)
+        }
+    }
+}
\ No newline at end of file
diff --git a/tests/net/integration/src/com/android/server/net/integrationtests/TestNetworkStackService.kt b/tests/net/integration/src/com/android/server/net/integrationtests/TestNetworkStackService.kt
new file mode 100644
index 0000000..8e4a9dd
--- /dev/null
+++ b/tests/net/integration/src/com/android/server/net/integrationtests/TestNetworkStackService.kt
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2019 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.net.integrationtests
+
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.net.INetworkMonitorCallbacks
+import android.net.Network
+import android.net.metrics.IpConnectivityLog
+import android.net.util.SharedLog
+import android.os.IBinder
+import com.android.networkstack.metrics.DataStallStatsUtils
+import com.android.server.NetworkStackService.NetworkMonitorConnector
+import com.android.server.NetworkStackService.NetworkStackConnector
+import com.android.server.connectivity.NetworkMonitor
+import com.android.server.net.integrationtests.NetworkStackInstrumentationService.InstrumentationConnector
+import org.mockito.Mockito.doReturn
+import org.mockito.Mockito.mock
+import org.mockito.Mockito.spy
+import java.net.HttpURLConnection
+import java.net.URL
+import java.net.URLConnection
+
+private const val TEST_NETID = 42
+
+/**
+ * Android service that can return an [android.net.INetworkStackConnector] which can be instrumented
+ * through [NetworkStackInstrumentationService].
+ * Useful in tests to create test instrumented NetworkStack components that can receive
+ * instrumentation commands through [NetworkStackInstrumentationService].
+ */
+class TestNetworkStackService : Service() {
+    override fun onBind(intent: Intent): IBinder = TestNetworkStackConnector(makeTestContext())
+
+    private fun makeTestContext() = spy(applicationContext).also {
+        doReturn(mock(IBinder::class.java)).`when`(it).getSystemService(Context.NETD_SERVICE)
+    }
+
+    private class TestPermissionChecker : NetworkStackConnector.PermissionChecker() {
+        override fun enforceNetworkStackCallingPermission() = Unit
+    }
+
+    private class NetworkMonitorDeps(private val privateDnsBypassNetwork: Network) :
+            NetworkMonitor.Dependencies() {
+        override fun getPrivateDnsBypassNetwork(network: Network?) = privateDnsBypassNetwork
+        override fun sendNetworkConditionsBroadcast(context: Context, broadcast: Intent) = Unit
+    }
+
+    private inner class TestNetworkStackConnector(context: Context) :
+            NetworkStackConnector(context, TestPermissionChecker()) {
+
+        private val network = Network(TEST_NETID)
+        private val privateDnsBypassNetwork = TestNetwork(TEST_NETID)
+
+        private inner class TestNetwork(netId: Int) : Network(netId) {
+            override fun openConnection(url: URL): URLConnection {
+                val response = InstrumentationConnector.processRequest(url)
+
+                val connection = mock(HttpURLConnection::class.java)
+                doReturn(response.responseCode).`when`(connection).responseCode
+                doReturn(response.contentLength).`when`(connection).contentLengthLong
+                doReturn(response.redirectUrl).`when`(connection).getHeaderField("location")
+                return connection
+            }
+        }
+
+        override fun makeNetworkMonitor(
+            network: Network,
+            name: String?,
+            cb: INetworkMonitorCallbacks
+        ) {
+            val nm = NetworkMonitor(this@TestNetworkStackService, cb,
+                    this.network,
+                    mock(IpConnectivityLog::class.java), mock(SharedLog::class.java),
+                    NetworkMonitorDeps(privateDnsBypassNetwork),
+                    mock(DataStallStatsUtils::class.java))
+            cb.onNetworkMonitorCreated(NetworkMonitorConnector(nm, TestPermissionChecker()))
+        }
+    }
+}
\ No newline at end of file