[BOT.3] Add unit test for polling network stats in the coordinator

Verify that the coordinator could fetch tether stats from BPF maps and
report the network stats to the service.

Bug: 150736748
Test: atest BpfCoordinatorTest
Change-Id: Ib1756159a2047c5db7d31359b0f288f840bd1bb1

Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java

@@ -41,6 +41,8 @@ import android.util.SparseArray;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+import com.android.internal.annotations.VisibleForTesting;
+
 /**
  *  This coordinator is responsible for providing BPF offload relevant functionality.
  *  - Get tethering stats.
@@ -49,10 +51,11 @@ import androidx.annotation.Nullable;
  */
 public class BpfCoordinator {
     private static final String TAG = BpfCoordinator.class.getSimpleName();
-    // TODO: Make it customizable.
+    @VisibleForTesting
-    private static final int DEFAULT_PERFORM_POLL_INTERVAL_MS = 5000;
+    static final int DEFAULT_PERFORM_POLL_INTERVAL_MS = 5000; // TODO: Make it customizable.
 
-    private enum StatsType {
+    @VisibleForTesting
+    enum StatsType {
         STATS_PER_IFACE,
         STATS_PER_UID,
     }
@@ -86,6 +89,7 @@ public class BpfCoordinator {
         maybeSchedulePollingStats();
     };
 
+    @VisibleForTesting
     static class Dependencies {
         int getPerformPollInterval() {
             // TODO: Consider make this configurable.
@@ -169,7 +173,8 @@ public class BpfCoordinator {
      * A BPF tethering stats provider to provide network statistics to the system.
      * Note that this class's data may only be accessed on the handler thread.
      */
-    private class BpfTetherStatsProvider extends NetworkStatsProvider {
+    @VisibleForTesting
+    class BpfTetherStatsProvider extends NetworkStatsProvider {
         // The offloaded traffic statistics per interface that has not been reported since the
         // last call to pushTetherStats. Only the interfaces that were ever tethering upstreams
         // and has pending tether stats delta are included in this NetworkStats object.
@@ -193,7 +198,8 @@ public class BpfCoordinator {
             // no-op
         }
 
-        private void pushTetherStats() {
+        @VisibleForTesting
+        void pushTetherStats() {
             try {
                 // The token is not used for now. See b/153606961.
                 notifyStatsUpdated(0 /* token */, mIfaceStats, mUidStats);

Tethering/tests/unit/src/com/android/networkstack/tethering/BpfCoordinatorTest.java

@@ -0,0 +1,207 @@
+/*
+ * Copyright (C) 2020 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.networkstack.tethering;
+
+import static android.net.NetworkStats.DEFAULT_NETWORK_NO;
+import static android.net.NetworkStats.METERED_NO;
+import static android.net.NetworkStats.ROAMING_NO;
+import static android.net.NetworkStats.SET_DEFAULT;
+import static android.net.NetworkStats.TAG_NONE;
+import static android.net.NetworkStats.UID_ALL;
+import static android.net.NetworkStats.UID_TETHERING;
+
+import static com.android.networkstack.tethering.BpfCoordinator
+        .DEFAULT_PERFORM_POLL_INTERVAL_MS;
+import static com.android.networkstack.tethering.BpfCoordinator.StatsType;
+import static com.android.networkstack.tethering.BpfCoordinator.StatsType.STATS_PER_IFACE;
+import static com.android.networkstack.tethering.BpfCoordinator.StatsType.STATS_PER_UID;
+
+import static junit.framework.Assert.assertNotNull;
+
+import static org.mockito.Matchers.anyString;
+import static org.mockito.Mockito.clearInvocations;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.annotation.NonNull;
+import android.app.usage.NetworkStatsManager;
+import android.net.INetd;
+import android.net.NetworkStats;
+import android.net.TetherStatsParcel;
+import android.net.util.SharedLog;
+import android.os.Handler;
+import android.os.test.TestLooper;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import com.android.testutils.TestableNetworkStatsProviderCbBinder;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.util.ArrayList;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class BpfCoordinatorTest {
+    @Mock private NetworkStatsManager mStatsManager;
+    @Mock private INetd mNetd;
+    // Late init since methods must be called by the thread that created this object.
+    private TestableNetworkStatsProviderCbBinder mTetherStatsProviderCb;
+    private BpfCoordinator.BpfTetherStatsProvider mTetherStatsProvider;
+    private final ArgumentCaptor<ArrayList> mStringArrayCaptor =
+            ArgumentCaptor.forClass(ArrayList.class);
+    private final TestLooper mTestLooper = new TestLooper();
+    private BpfCoordinator.Dependencies mDeps =
+            new BpfCoordinator.Dependencies() {
+            @Override
+            int getPerformPollInterval() {
+                return DEFAULT_PERFORM_POLL_INTERVAL_MS;
+            }
+    };
+
+    @Before public void setUp() {
+        MockitoAnnotations.initMocks(this);
+    }
+
+    private void waitForIdle() {
+        mTestLooper.dispatchAll();
+    }
+
+    private void setupFunctioningNetdInterface() throws Exception {
+        when(mNetd.tetherOffloadGetStats()).thenReturn(new TetherStatsParcel[0]);
+    }
+
+    @NonNull
+    private BpfCoordinator makeBpfCoordinator() throws Exception {
+        BpfCoordinator coordinator = new BpfCoordinator(
+                new Handler(mTestLooper.getLooper()), mNetd, mStatsManager, new SharedLog("test"),
+                mDeps);
+        final ArgumentCaptor<BpfCoordinator.BpfTetherStatsProvider>
+                tetherStatsProviderCaptor =
+                ArgumentCaptor.forClass(BpfCoordinator.BpfTetherStatsProvider.class);
+        verify(mStatsManager).registerNetworkStatsProvider(anyString(),
+                tetherStatsProviderCaptor.capture());
+        mTetherStatsProvider = tetherStatsProviderCaptor.getValue();
+        assertNotNull(mTetherStatsProvider);
+        mTetherStatsProviderCb = new TestableNetworkStatsProviderCbBinder();
+        mTetherStatsProvider.setProviderCallbackBinder(mTetherStatsProviderCb);
+        return coordinator;
+    }
+
+    @NonNull
+    private static NetworkStats.Entry buildTestEntry(@NonNull StatsType how,
+            @NonNull String iface, long rxBytes, long rxPackets, long txBytes, long txPackets) {
+        return new NetworkStats.Entry(iface, how == STATS_PER_IFACE ? UID_ALL : UID_TETHERING,
+                SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO, DEFAULT_NETWORK_NO, rxBytes,
+                rxPackets, txBytes, txPackets, 0L);
+    }
+
+    @NonNull
+    private static TetherStatsParcel buildTestTetherStatsParcel(@NonNull Integer ifIndex,
+            long rxBytes, long rxPackets, long txBytes, long txPackets) {
+        final TetherStatsParcel parcel = new TetherStatsParcel();
+        parcel.ifIndex = ifIndex;
+        parcel.rxBytes = rxBytes;
+        parcel.rxPackets = rxPackets;
+        parcel.txBytes = txBytes;
+        parcel.txPackets = txPackets;
+        return parcel;
+    }
+
+    private void setTetherOffloadStatsList(TetherStatsParcel[] tetherStatsList) throws Exception {
+        when(mNetd.tetherOffloadGetStats()).thenReturn(tetherStatsList);
+        mTestLooper.moveTimeForward(DEFAULT_PERFORM_POLL_INTERVAL_MS);
+        waitForIdle();
+    }
+
+    @Test
+    public void testGetForwardedStats() throws Exception {
+        setupFunctioningNetdInterface();
+
+        final BpfCoordinator coordinator = makeBpfCoordinator();
+        coordinator.start();
+
+        final String wlanIface = "wlan0";
+        final Integer wlanIfIndex = 100;
+        final String mobileIface = "rmnet_data0";
+        final Integer mobileIfIndex = 101;
+
+        // Add interface name to lookup table. In realistic case, the upstream interface name will
+        // be added by IpServer when IpServer has received with a new IPv6 upstream update event.
+        coordinator.addUpstreamNameToLookupTable(wlanIfIndex, wlanIface);
+        coordinator.addUpstreamNameToLookupTable(mobileIfIndex, mobileIface);
+
+        // [1] Both interface stats are changed.
+        // Setup the tether stats of wlan and mobile interface. Note that move forward the time of
+        // the looper to make sure the new tether stats has been updated by polling update thread.
+        setTetherOffloadStatsList(new TetherStatsParcel[] {
+                buildTestTetherStatsParcel(wlanIfIndex, 1000, 100, 2000, 200),
+                buildTestTetherStatsParcel(mobileIfIndex, 3000, 300, 4000, 400)});
+
+        final NetworkStats expectedIfaceStats = new NetworkStats(0L, 2)
+                .addEntry(buildTestEntry(STATS_PER_IFACE, wlanIface, 1000, 100, 2000, 200))
+                .addEntry(buildTestEntry(STATS_PER_IFACE, mobileIface, 3000, 300, 4000, 400));
+
+        final NetworkStats expectedUidStats = new NetworkStats(0L, 2)
+                .addEntry(buildTestEntry(STATS_PER_UID, wlanIface, 1000, 100, 2000, 200))
+                .addEntry(buildTestEntry(STATS_PER_UID, mobileIface, 3000, 300, 4000, 400));
+
+        // Force pushing stats update to verify the stats reported.
+        // TODO: Perhaps make #expectNotifyStatsUpdated to use test TetherStatsParcel object for
+        // verifying the notification.
+        mTetherStatsProvider.pushTetherStats();
+        mTetherStatsProviderCb.expectNotifyStatsUpdated(expectedIfaceStats, expectedUidStats);
+
+        // [2] Only one interface stats is changed.
+        // The tether stats of mobile interface is accumulated and The tether stats of wlan
+        // interface is the same.
+        setTetherOffloadStatsList(new TetherStatsParcel[] {
+                buildTestTetherStatsParcel(wlanIfIndex, 1000, 100, 2000, 200),
+                buildTestTetherStatsParcel(mobileIfIndex, 3010, 320, 4030, 440)});
+
+        final NetworkStats expectedIfaceStatsDiff = new NetworkStats(0L, 2)
+                .addEntry(buildTestEntry(STATS_PER_IFACE, wlanIface, 0, 0, 0, 0))
+                .addEntry(buildTestEntry(STATS_PER_IFACE, mobileIface, 10, 20, 30, 40));
+
+        final NetworkStats expectedUidStatsDiff = new NetworkStats(0L, 2)
+                .addEntry(buildTestEntry(STATS_PER_UID, wlanIface, 0, 0, 0, 0))
+                .addEntry(buildTestEntry(STATS_PER_UID, mobileIface, 10, 20, 30, 40));
+
+        // Force pushing stats update to verify that only diff of stats is reported.
+        mTetherStatsProvider.pushTetherStats();
+        mTetherStatsProviderCb.expectNotifyStatsUpdated(expectedIfaceStatsDiff,
+                expectedUidStatsDiff);
+
+        // [3] Stop coordinator.
+        // Shutdown the coordinator and clear the invocation history, especially the
+        // tetherOffloadGetStats() calls.
+        coordinator.stop();
+        clearInvocations(mNetd);
+
+        // Verify the polling update thread stopped.
+        mTestLooper.moveTimeForward(DEFAULT_PERFORM_POLL_INTERVAL_MS);
+        waitForIdle();
+        verify(mNetd, never()).tetherOffloadGetStats();
+    }
+}