Add a method to get the total network usage.

import android.util.Pair;

import com.android.internal.R;

import com.android.internal.annotations.VisibleForTesting;

import java.time.ZonedDateTime;

import java.util.Date;

                * mContext.getResources().getInteger(R.integer.default_data_warning_level_mb);

    }

    private INetworkStatsSession getSession() {

    @VisibleForTesting

    INetworkStatsSession getSession() {

        if (mSession == null) {

            try {

                mSession = mStatsService.openSession();

        }

    }

    /**

     * Get the total usage level recorded in the network history

     * @param template the network template to retrieve the network history

     * @return the total usage level recorded in the network history

     */

    public long getHistoriclUsageLevel(NetworkTemplate template) {

        final INetworkStatsSession session = getSession();

        if (session != null) {

            try {

                final NetworkStatsHistory history = session.getHistoryForNetwork(template, FIELDS);

                final long now = System.currentTimeMillis();

                final NetworkStatsHistory.Entry entry =

                        history.getValues(0L /* start */, now /* end */, now, null /* recycle */);

                if (entry != null) {

                    return entry.rxBytes + entry.txBytes;

                }

                Log.w(TAG, "Failed to get data usage, no entry data");

            } catch (RemoteException e) {

                Log.w(TAG, "Failed to get data usage, remote call failed");

            }

        }

        return 0L;

    }

    private NetworkPolicy findNetworkPolicy(NetworkTemplate template) {

        if (mPolicyManager == null || template == null) return null;

        final NetworkPolicy[] policies = mPolicyManager.getNetworkPolicies();

/*

 * 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 com.android.settingslib.net;

import static com.google.common.truth.Truth.assertThat;

import static org.mockito.ArgumentMatchers.nullable;

import static org.mockito.Mockito.any;

import static org.mockito.Mockito.anyInt;

import static org.mockito.Mockito.anyLong;

import static org.mockito.Mockito.doReturn;

import static org.mockito.Mockito.eq;

import static org.mockito.Mockito.spy;

import static org.mockito.Mockito.when;

import android.content.Context;

import android.net.INetworkStatsSession;

import android.net.NetworkStatsHistory;

import android.net.NetworkStatsHistory.Entry;

import android.net.NetworkTemplate;

import android.os.RemoteException;

import android.text.format.DateUtils;

import com.android.settingslib.SettingsLibRobolectricTestRunner;

import org.junit.Before;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.mockito.Mock;

import org.mockito.MockitoAnnotations;

import org.robolectric.RuntimeEnvironment;

@RunWith(SettingsLibRobolectricTestRunner.class)

public class DataUsageControllerTest {

    @Mock

    private INetworkStatsSession mSession;

    private Context mContext;

    private DataUsageController mController;

    private NetworkStatsHistory mNetworkStatsHistory;

    @Before

    public void setUp() throws RemoteException {

        MockitoAnnotations.initMocks(this);

        mContext = RuntimeEnvironment.application;

        mController = spy(new DataUsageController(mContext));

        mNetworkStatsHistory = spy(

                new NetworkStatsHistory(DateUtils.DAY_IN_MILLIS /* bucketDuration */));

        doReturn(mNetworkStatsHistory)

                .when(mSession).getHistoryForNetwork(any(NetworkTemplate.class), anyInt());

    }

    @Test

    public void getHistoriclUsageLevel_noNetworkSession_shouldReturn0() {

        doReturn(null).when(mController).getSession();

        assertThat(mController.getHistoriclUsageLevel(null /* template */)).isEqualTo(0L);

    }

    @Test

    public void getHistoriclUsageLevel_noUsageData_shouldReturn0() {

        doReturn(mSession).when(mController).getSession();

        assertThat(mController.getHistoriclUsageLevel(NetworkTemplate.buildTemplateWifiWildcard()))

                .isEqualTo(0L);

    }

    @Test

    public void getHistoriclUsageLevel_hasUsageData_shouldReturnTotalUsage() {

        doReturn(mSession).when(mController).getSession();

        final long receivedBytes = 743823454L;

        final long transmittedBytes = 16574289L;

        final Entry entry = new Entry();

        entry.bucketStart = 1521583200000L;

        entry.rxBytes = receivedBytes;

        entry.txBytes = transmittedBytes;

        when(mNetworkStatsHistory.getValues(eq(0L), anyLong(), anyLong(), nullable(Entry.class)))

                .thenReturn(entry);

        assertThat(mController.getHistoriclUsageLevel(NetworkTemplate.buildTemplateWifiWildcard()))

                .isEqualTo(receivedBytes + transmittedBytes);

    }

}