diff --git a/tests/net/java/android/app/usage/NetworkStatsManagerTest.java b/tests/net/java/android/app/usage/NetworkStatsManagerTest.java
new file mode 100644
index 0000000..25e1474
--- /dev/null
+++ b/tests/net/java/android/app/usage/NetworkStatsManagerTest.java
@@ -0,0 +1,213 @@
+/*
+ * Copyright (C) 2018 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.app.usage;
+
+import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertTrue;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.argThat;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.atLeastOnce;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.net.ConnectivityManager;
+import android.net.INetworkStatsService;
+import android.net.INetworkStatsSession;
+import android.net.NetworkStats.Entry;
+import android.net.NetworkStatsHistory;
+import android.net.NetworkTemplate;
+import android.os.RemoteException;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.mockito.invocation.InvocationOnMock;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class NetworkStatsManagerTest {
+
+    private @Mock INetworkStatsService mService;
+    private @Mock INetworkStatsSession mStatsSession;
+
+    private NetworkStatsManager mManager;
+
+    // TODO: change to NetworkTemplate.MATCH_MOBILE once internal constant rename is merged to aosp.
+    private static final int MATCH_MOBILE_ALL = 1;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+        mManager = new NetworkStatsManager(InstrumentationRegistry.getContext(), mService);
+    }
+
+    @Test
+    public void testQueryDetails() throws RemoteException {
+        final String subscriberId = "subid";
+        final long startTime = 1;
+        final long endTime = 100;
+        final int uid1 = 10001;
+        final int uid2 = 10002;
+        final int uid3 = 10003;
+
+        Entry uid1Entry1 = new Entry("if1", uid1,
+                android.net.NetworkStats.SET_DEFAULT, android.net.NetworkStats.TAG_NONE,
+                100, 10, 200, 20, 0);
+
+        Entry uid1Entry2 = new Entry(
+                "if2", uid1,
+                android.net.NetworkStats.SET_DEFAULT, android.net.NetworkStats.TAG_NONE,
+                100, 10, 200, 20, 0);
+
+        Entry uid2Entry1 = new Entry("if1", uid2,
+                android.net.NetworkStats.SET_DEFAULT, android.net.NetworkStats.TAG_NONE,
+                150, 10, 250, 20, 0);
+
+        Entry uid2Entry2 = new Entry(
+                "if2", uid2,
+                android.net.NetworkStats.SET_DEFAULT, android.net.NetworkStats.TAG_NONE,
+                150, 10, 250, 20, 0);
+
+        NetworkStatsHistory history1 = new NetworkStatsHistory(10, 2);
+        history1.recordData(10, 20, uid1Entry1);
+        history1.recordData(20, 30, uid1Entry2);
+
+        NetworkStatsHistory history2 = new NetworkStatsHistory(10, 2);
+        history1.recordData(30, 40, uid2Entry1);
+        history1.recordData(35, 45, uid2Entry2);
+
+
+        when(mService.openSessionForUsageStats(anyInt(), anyString())).thenReturn(mStatsSession);
+        when(mStatsSession.getRelevantUids()).thenReturn(new int[] { uid1, uid2, uid3 });
+
+        when(mStatsSession.getHistoryIntervalForUid(any(NetworkTemplate.class),
+                eq(uid1), eq(android.net.NetworkStats.SET_ALL),
+                eq(android.net.NetworkStats.TAG_NONE),
+                eq(NetworkStatsHistory.FIELD_ALL), eq(startTime), eq(endTime)))
+                .then((InvocationOnMock inv) -> {
+                    NetworkTemplate template = inv.getArgument(0);
+                    assertEquals(MATCH_MOBILE_ALL, template.getMatchRule());
+                    assertEquals(subscriberId, template.getSubscriberId());
+                    return history1;
+                });
+
+        when(mStatsSession.getHistoryIntervalForUid(any(NetworkTemplate.class),
+                eq(uid2), eq(android.net.NetworkStats.SET_ALL),
+                eq(android.net.NetworkStats.TAG_NONE),
+                eq(NetworkStatsHistory.FIELD_ALL), eq(startTime), eq(endTime)))
+                .then((InvocationOnMock inv) -> {
+                    NetworkTemplate template = inv.getArgument(0);
+                    assertEquals(MATCH_MOBILE_ALL, template.getMatchRule());
+                    assertEquals(subscriberId, template.getSubscriberId());
+                    return history2;
+                });
+
+
+        NetworkStats stats = mManager.queryDetails(
+                ConnectivityManager.TYPE_MOBILE, subscriberId, startTime, endTime);
+
+        NetworkStats.Bucket bucket = new NetworkStats.Bucket();
+
+        // First 2 buckets exactly match entry timings
+        assertTrue(stats.getNextBucket(bucket));
+        assertEquals(10, bucket.getStartTimeStamp());
+        assertEquals(20, bucket.getEndTimeStamp());
+        assertBucketMatches(uid1Entry1, bucket);
+
+        assertTrue(stats.getNextBucket(bucket));
+        assertEquals(20, bucket.getStartTimeStamp());
+        assertEquals(30, bucket.getEndTimeStamp());
+        assertBucketMatches(uid1Entry2, bucket);
+
+        // 30 -> 40: contains uid2Entry1 and half of uid2Entry2
+        assertTrue(stats.getNextBucket(bucket));
+        assertEquals(30, bucket.getStartTimeStamp());
+        assertEquals(40, bucket.getEndTimeStamp());
+        assertEquals(225, bucket.getRxBytes());
+        assertEquals(15, bucket.getRxPackets());
+        assertEquals(375, bucket.getTxBytes());
+        assertEquals(30, bucket.getTxPackets());
+
+        // 40 -> 50: contains half of uid2Entry2
+        assertTrue(stats.getNextBucket(bucket));
+        assertEquals(40, bucket.getStartTimeStamp());
+        assertEquals(50, bucket.getEndTimeStamp());
+        assertEquals(75, bucket.getRxBytes());
+        assertEquals(5, bucket.getRxPackets());
+        assertEquals(125, bucket.getTxBytes());
+        assertEquals(10, bucket.getTxPackets());
+
+        assertFalse(stats.hasNextBucket());
+    }
+
+    @Test
+    public void testQueryDetails_NoSubscriberId() throws RemoteException {
+        final long startTime = 1;
+        final long endTime = 100;
+        final int uid1 = 10001;
+        final int uid2 = 10002;
+
+        when(mService.openSessionForUsageStats(anyInt(), anyString())).thenReturn(mStatsSession);
+        when(mStatsSession.getRelevantUids()).thenReturn(new int[] { uid1, uid2 });
+
+        NetworkStats stats = mManager.queryDetails(
+                ConnectivityManager.TYPE_MOBILE, null, startTime, endTime);
+
+        when(mStatsSession.getHistoryIntervalForUid(any(NetworkTemplate.class),
+                anyInt(), anyInt(), anyInt(), anyInt(), anyLong(), anyLong()))
+                .thenReturn(new NetworkStatsHistory(10, 0));
+
+        verify(mStatsSession, times(1)).getHistoryIntervalForUid(
+                argThat((NetworkTemplate t) ->
+                        // No subscriberId: MATCH_MOBILE_WILDCARD template
+                        t.getMatchRule() == NetworkTemplate.MATCH_MOBILE_WILDCARD),
+                eq(uid1), eq(android.net.NetworkStats.SET_ALL),
+                eq(android.net.NetworkStats.TAG_NONE),
+                eq(NetworkStatsHistory.FIELD_ALL), eq(startTime), eq(endTime));
+
+        verify(mStatsSession, times(1)).getHistoryIntervalForUid(
+                argThat((NetworkTemplate t) ->
+                        // No subscriberId: MATCH_MOBILE_WILDCARD template
+                        t.getMatchRule() == NetworkTemplate.MATCH_MOBILE_WILDCARD),
+                eq(uid2), eq(android.net.NetworkStats.SET_ALL),
+                eq(android.net.NetworkStats.TAG_NONE),
+                eq(NetworkStatsHistory.FIELD_ALL), eq(startTime), eq(endTime));
+
+        assertFalse(stats.hasNextBucket());
+    }
+
+    private void assertBucketMatches(Entry expected,
+            NetworkStats.Bucket actual) {
+        assertEquals(expected.uid, actual.getUid());
+        assertEquals(expected.rxBytes, actual.getRxBytes());
+        assertEquals(expected.rxPackets, actual.getRxPackets());
+        assertEquals(expected.txBytes, actual.getTxBytes());
+        assertEquals(expected.txPackets, actual.getTxPackets());
+    }
+}