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Testing DefaultBandwidthMeter Network Estimation in SmartTube

This test suite validates the DefaultBandwidthMeter class in ExoPlayer, focusing on initial bitrate estimates across different network types and country scenarios. The tests verify bandwidth measurement behavior for WiFi, mobile networks (2G/3G/4G), and Ethernet connections.
Test Coverage Overview

The test suite provides comprehensive coverage of bandwidth estimation functionality:
Initial bitrate estimates for different network types (WiFi, 2G, 3G, 4G, Ethernet)
Country-specific bandwidth variations
Network type override scenarios
Offline state handling
Transfer simulation across network conditions
Implementation Analysis

The testing approach uses JUnit and Robolectric for Android environment simulation. The implementation leverages shadow classes to mock network conditions and telephony services. Tests validate bitrate estimates through comparison assertions and simulated data transfers.
Technical Details

Key technical components include:
JUnit 4 test framework
Robolectric for Android testing
Shadow classes for network/telephony mocking
FakeClock for time simulation
FakeDataSource for transfer simulation
Best Practices Demonstrated

The test suite exemplifies several testing best practices:
Comprehensive setup of test environment using @Before
Systematic validation of network type comparisons
Isolation of test scenarios using mock objects
Clear test method naming conventions
Thorough edge case coverage
yuliskov/smarttube

exoplayer-amzn-2.10.6/library/core/src/test/java/com/google/android/exoplayer2/upstream/DefaultBandwidthMeterTest.java
            
/*
 * 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.google.android.exoplayer2.upstream;

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

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.NetworkInfo.DetailedState;
import android.net.Uri;
import android.telephony.TelephonyManager;
import androidx.test.core.app.ApplicationProvider;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import com.google.android.exoplayer2.C;
import com.google.android.exoplayer2.testutil.FakeClock;
import com.google.android.exoplayer2.testutil.FakeDataSource;
import java.util.Random;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.robolectric.Shadows;
import org.robolectric.shadows.ShadowNetworkInfo;

/** Unit test for {@link DefaultBandwidthMeter}. */
@RunWith(AndroidJUnit4.class)
public final class DefaultBandwidthMeterTest {

  private static final int SIMULATED_TRANSFER_COUNT = 100;
  private static final String FAST_COUNTRY_ISO = "EE";
  private static final String SLOW_COUNTRY_ISO = "PG";

  private TelephonyManager telephonyManager;
  private ConnectivityManager connectivityManager;
  private NetworkInfo networkInfoOffline;
  private NetworkInfo networkInfoWifi;
  private NetworkInfo networkInfo2g;
  private NetworkInfo networkInfo3g;
  private NetworkInfo networkInfo4g;
  private NetworkInfo networkInfoEthernet;

  @Before
  public void setUp() {
    connectivityManager =
        (ConnectivityManager)
            ApplicationProvider.getApplicationContext()
                .getSystemService(Context.CONNECTIVITY_SERVICE);
    telephonyManager =
        (TelephonyManager)
            ApplicationProvider.getApplicationContext().getSystemService(Context.TELEPHONY_SERVICE);
    Shadows.shadowOf(telephonyManager).setNetworkCountryIso(FAST_COUNTRY_ISO);
    networkInfoOffline =
        ShadowNetworkInfo.newInstance(
            DetailedState.DISCONNECTED,
            ConnectivityManager.TYPE_WIFI,
            /* subType= */ 0,
            /* isAvailable= */ false,
            /* isConnected= */ false);
    networkInfoWifi =
        ShadowNetworkInfo.newInstance(
            DetailedState.CONNECTED,
            ConnectivityManager.TYPE_WIFI,
            /* subType= */ 0,
            /* isAvailable= */ true,
            /* isConnected= */ true);
    networkInfo2g =
        ShadowNetworkInfo.newInstance(
            DetailedState.CONNECTED,
            ConnectivityManager.TYPE_MOBILE,
            TelephonyManager.NETWORK_TYPE_GPRS,
            /* isAvailable= */ true,
            /* isConnected= */ true);
    networkInfo3g =
        ShadowNetworkInfo.newInstance(
            DetailedState.CONNECTED,
            ConnectivityManager.TYPE_MOBILE,
            TelephonyManager.NETWORK_TYPE_HSDPA,
            /* isAvailable= */ true,
            /* isConnected= */ true);
    networkInfo4g =
        ShadowNetworkInfo.newInstance(
            DetailedState.CONNECTED,
            ConnectivityManager.TYPE_MOBILE,
            TelephonyManager.NETWORK_TYPE_LTE,
            /* isAvailable= */ true,
            /* isConnected= */ true);
    networkInfoEthernet =
        ShadowNetworkInfo.newInstance(
            DetailedState.CONNECTED,
            ConnectivityManager.TYPE_ETHERNET,
            /* subType= */ 0,
            /* isAvailable= */ true,
            /* isConnected= */ true);
  }
  
  @Test
  public void defaultInitialBitrateEstimate_forWifi_isGreaterThanEstimateFor2G() {
    setActiveNetworkInfo(networkInfoWifi);
    DefaultBandwidthMeter bandwidthMeterWifi =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateWifi = bandwidthMeterWifi.getBitrateEstimate();

    setActiveNetworkInfo(networkInfo2g);
    DefaultBandwidthMeter bandwidthMeter2g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate2g = bandwidthMeter2g.getBitrateEstimate();

    assertThat(initialEstimateWifi).isGreaterThan(initialEstimate2g);
  }

  @Test
  public void defaultInitialBitrateEstimate_forWifi_isGreaterThanEstimateFor3G() {
    setActiveNetworkInfo(networkInfoWifi);
    DefaultBandwidthMeter bandwidthMeterWifi =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateWifi = bandwidthMeterWifi.getBitrateEstimate();

    setActiveNetworkInfo(networkInfo3g);
    DefaultBandwidthMeter bandwidthMeter3g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate3g = bandwidthMeter3g.getBitrateEstimate();

    assertThat(initialEstimateWifi).isGreaterThan(initialEstimate3g);
  }

  @Test
  public void defaultInitialBitrateEstimate_forEthernet_isGreaterThanEstimateFor2G() {
    setActiveNetworkInfo(networkInfoEthernet);
    DefaultBandwidthMeter bandwidthMeterEthernet =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateEthernet = bandwidthMeterEthernet.getBitrateEstimate();

    setActiveNetworkInfo(networkInfo2g);
    DefaultBandwidthMeter bandwidthMeter2g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate2g = bandwidthMeter2g.getBitrateEstimate();

    assertThat(initialEstimateEthernet).isGreaterThan(initialEstimate2g);
  }

  @Test
  public void defaultInitialBitrateEstimate_forEthernet_isGreaterThanEstimateFor3G() {
    setActiveNetworkInfo(networkInfoEthernet);
    DefaultBandwidthMeter bandwidthMeterEthernet =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateEthernet = bandwidthMeterEthernet.getBitrateEstimate();

    setActiveNetworkInfo(networkInfo3g);
    DefaultBandwidthMeter bandwidthMeter3g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate3g = bandwidthMeter3g.getBitrateEstimate();

    assertThat(initialEstimateEthernet).isGreaterThan(initialEstimate3g);
  }

  @Test
  public void defaultInitialBitrateEstimate_for4G_isGreaterThanEstimateFor2G() {
    setActiveNetworkInfo(networkInfo4g);
    DefaultBandwidthMeter bandwidthMeter4g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate4g = bandwidthMeter4g.getBitrateEstimate();

    setActiveNetworkInfo(networkInfo2g);
    DefaultBandwidthMeter bandwidthMeter2g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate2g = bandwidthMeter2g.getBitrateEstimate();

    assertThat(initialEstimate4g).isGreaterThan(initialEstimate2g);
  }

  @Test
  public void defaultInitialBitrateEstimate_for4G_isGreaterThanEstimateFor3G() {
    setActiveNetworkInfo(networkInfo4g);
    DefaultBandwidthMeter bandwidthMeter4g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate4g = bandwidthMeter4g.getBitrateEstimate();

    setActiveNetworkInfo(networkInfo3g);
    DefaultBandwidthMeter bandwidthMeter3g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate3g = bandwidthMeter3g.getBitrateEstimate();

    assertThat(initialEstimate4g).isGreaterThan(initialEstimate3g);
  }

  @Test
  public void defaultInitialBitrateEstimate_for3G_isGreaterThanEstimateFor2G() {
    setActiveNetworkInfo(networkInfo3g);
    DefaultBandwidthMeter bandwidthMeter3g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate3g = bandwidthMeter3g.getBitrateEstimate();

    setActiveNetworkInfo(networkInfo2g);
    DefaultBandwidthMeter bandwidthMeter2g =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate2g = bandwidthMeter2g.getBitrateEstimate();

    assertThat(initialEstimate3g).isGreaterThan(initialEstimate2g);
  }

  @Test
  public void defaultInitialBitrateEstimate_forOffline_isReasonable() {
    setActiveNetworkInfo(networkInfoOffline);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isGreaterThan(100_000L);
    assertThat(initialEstimate).isLessThan(50_000_000L);
  }

  @Test
  public void
      defaultInitialBitrateEstimate_forWifi_forFastCountry_isGreaterThanEstimateForSlowCountry() {
    setActiveNetworkInfo(networkInfoWifi);
    setNetworkCountryIso(FAST_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterFast =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateFast = bandwidthMeterFast.getBitrateEstimate();

    setNetworkCountryIso(SLOW_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterSlow =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateSlow = bandwidthMeterSlow.getBitrateEstimate();

    assertThat(initialEstimateFast).isGreaterThan(initialEstimateSlow);
  }

  @Test
  public void
      defaultInitialBitrateEstimate_forEthernet_forFastCountry_isGreaterThanEstimateForSlowCountry() {
    setActiveNetworkInfo(networkInfoEthernet);
    setNetworkCountryIso(FAST_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterFast =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateFast = bandwidthMeterFast.getBitrateEstimate();

    setNetworkCountryIso(SLOW_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterSlow =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateSlow = bandwidthMeterSlow.getBitrateEstimate();

    assertThat(initialEstimateFast).isGreaterThan(initialEstimateSlow);
  }

  @Test
  public void
      defaultInitialBitrateEstimate_for2G_forFastCountry_isGreaterThanEstimateForSlowCountry() {
    setActiveNetworkInfo(networkInfo2g);
    setNetworkCountryIso(FAST_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterFast =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateFast = bandwidthMeterFast.getBitrateEstimate();

    setNetworkCountryIso(SLOW_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterSlow =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateSlow = bandwidthMeterSlow.getBitrateEstimate();

    assertThat(initialEstimateFast).isGreaterThan(initialEstimateSlow);
  }

  @Test
  public void
      defaultInitialBitrateEstimate_for3G_forFastCountry_isGreaterThanEstimateForSlowCountry() {
    setActiveNetworkInfo(networkInfo3g);
    setNetworkCountryIso(FAST_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterFast =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateFast = bandwidthMeterFast.getBitrateEstimate();

    setNetworkCountryIso(SLOW_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterSlow =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateSlow = bandwidthMeterSlow.getBitrateEstimate();

    assertThat(initialEstimateFast).isGreaterThan(initialEstimateSlow);
  }

  @Test
  public void
      defaultInitialBitrateEstimate_for4g_forFastCountry_isGreaterThanEstimateForSlowCountry() {
    setActiveNetworkInfo(networkInfo4g);
    setNetworkCountryIso(FAST_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterFast =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateFast = bandwidthMeterFast.getBitrateEstimate();

    setNetworkCountryIso(SLOW_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterSlow =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateSlow = bandwidthMeterSlow.getBitrateEstimate();

    assertThat(initialEstimateFast).isGreaterThan(initialEstimateSlow);
  }

  @Test
  public void initialBitrateEstimateOverwrite_whileConnectedToNetwork_setsInitialEstimate() {
    setActiveNetworkInfo(networkInfoWifi);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isEqualTo(123456789);
  }

  @Test
  public void initialBitrateEstimateOverwrite_whileOffline_setsInitialEstimate() {
    setActiveNetworkInfo(networkInfoOffline);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isEqualTo(123456789);
  }

  @Test
  public void initialBitrateEstimateOverwrite_forWifi_whileConnectedToWifi_setsInitialEstimate() {
    setActiveNetworkInfo(networkInfoWifi);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_WIFI, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isEqualTo(123456789);
  }

  @Test
  public void
      initialBitrateEstimateOverwrite_forWifi_whileConnectedToOtherNetwork_doesNotSetInitialEstimate() {
    setActiveNetworkInfo(networkInfo2g);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_WIFI, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isNotEqualTo(123456789);
  }

  @Test
  public void
      initialBitrateEstimateOverwrite_forEthernet_whileConnectedToEthernet_setsInitialEstimate() {
    setActiveNetworkInfo(networkInfoEthernet);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_ETHERNET, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isEqualTo(123456789);
  }

  @Test
  public void
      initialBitrateEstimateOverwrite_forEthernet_whileConnectedToOtherNetwork_doesNotSetInitialEstimate() {
    setActiveNetworkInfo(networkInfo2g);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_WIFI, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isNotEqualTo(123456789);
  }

  @Test
  public void initialBitrateEstimateOverwrite_for2G_whileConnectedTo2G_setsInitialEstimate() {
    setActiveNetworkInfo(networkInfo2g);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_2G, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isEqualTo(123456789);
  }

  @Test
  public void
      initialBitrateEstimateOverwrite_for2G_whileConnectedToOtherNetwork_doesNotSetInitialEstimate() {
    setActiveNetworkInfo(networkInfoWifi);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_2G, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isNotEqualTo(123456789);
  }

  @Test
  public void initialBitrateEstimateOverwrite_for3G_whileConnectedTo3G_setsInitialEstimate() {
    setActiveNetworkInfo(networkInfo3g);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_3G, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isEqualTo(123456789);
  }

  @Test
  public void
      initialBitrateEstimateOverwrite_for3G_whileConnectedToOtherNetwork_doesNotSetInitialEstimate() {
    setActiveNetworkInfo(networkInfoWifi);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_3G, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isNotEqualTo(123456789);
  }

  @Test
  public void initialBitrateEstimateOverwrite_for4G_whileConnectedTo4G_setsInitialEstimate() {
    setActiveNetworkInfo(networkInfo4g);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_4G, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isEqualTo(123456789);
  }

  @Test
  public void
      initialBitrateEstimateOverwrite_for4G_whileConnectedToOtherNetwork_doesNotSetInitialEstimate() {
    setActiveNetworkInfo(networkInfoWifi);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_4G, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isNotEqualTo(123456789);
  }

  @Test
  public void initialBitrateEstimateOverwrite_forOffline_whileOffline_setsInitialEstimate() {
    setActiveNetworkInfo(networkInfoOffline);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_OFFLINE, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isEqualTo(123456789);
  }

  @Test
  public void
      initialBitrateEstimateOverwrite_forOffline_whileConnectedToNetwork_doesNotSetInitialEstimate() {
    setActiveNetworkInfo(networkInfoWifi);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(C.NETWORK_TYPE_OFFLINE, 123456789)
            .build();
    long initialEstimate = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimate).isNotEqualTo(123456789);
  }

  @Test
  public void initialBitrateEstimateOverwrite_forCountry_usesDefaultValuesForCountry() {
    setNetworkCountryIso(SLOW_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterSlow =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateSlow = bandwidthMeterSlow.getBitrateEstimate();

    setNetworkCountryIso(FAST_COUNTRY_ISO);
    DefaultBandwidthMeter bandwidthMeterFastWithSlowOverwrite =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setInitialBitrateEstimate(SLOW_COUNTRY_ISO)
            .build();
    long initialEstimateFastWithSlowOverwrite =
        bandwidthMeterFastWithSlowOverwrite.getBitrateEstimate();

    assertThat(initialEstimateFastWithSlowOverwrite).isEqualTo(initialEstimateSlow);
  }

  @Test
  public void networkTypeOverride_updatesBitrateEstimate() {
    setActiveNetworkInfo(networkInfoEthernet);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext()).build();
    long initialEstimateEthernet = bandwidthMeter.getBitrateEstimate();

    bandwidthMeter.setNetworkTypeOverride(C.NETWORK_TYPE_2G);
    long initialEstimate2g = bandwidthMeter.getBitrateEstimate();

    assertThat(initialEstimateEthernet).isGreaterThan(initialEstimate2g);
  }

  @Test
  public void networkTypeOverride_doesFullReset() {
    // Simulate transfers for an ethernet connection.
    setActiveNetworkInfo(networkInfoEthernet);
    FakeClock clock = new FakeClock(/* initialTimeMs= */ 0);
    DefaultBandwidthMeter bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setClock(clock)
            .build();
    long[] bitrateEstimatesWithNewInstance = simulateTransfers(bandwidthMeter, clock);

    // Create a new instance and seed with some transfers.
    setActiveNetworkInfo(networkInfo2g);
    bandwidthMeter =
        new DefaultBandwidthMeter.Builder(ApplicationProvider.getApplicationContext())
            .setClock(clock)
            .build();
    simulateTransfers(bandwidthMeter, clock);

    // Override the network type to ethernet and simulate transfers again.
    bandwidthMeter.setNetworkTypeOverride(C.NETWORK_TYPE_ETHERNET);
    long[] bitrateEstimatesAfterReset = simulateTransfers(bandwidthMeter, clock);

    // If overriding the network type fully reset the bandwidth meter, we expect the bitrate
    // estimates generated during simulation to be the same.
    assertThat(bitrateEstimatesAfterReset).isEqualTo(bitrateEstimatesWithNewInstance);
  }

  @Test
  @SuppressWarnings("deprecation")
  public void defaultInitialBitrateEstimate_withoutContext_isReasonable() {
    DefaultBandwidthMeter bandwidthMeterWithBuilder =
        new DefaultBandwidthMeter.Builder(/* context= */ null).build();
    long initialEstimateWithBuilder = bandwidthMeterWithBuilder.getBitrateEstimate();

    DefaultBandwidthMeter bandwidthMeterWithoutBuilder = new DefaultBandwidthMeter();
    long initialEstimateWithoutBuilder = bandwidthMeterWithoutBuilder.getBitrateEstimate();

    assertThat(initialEstimateWithBuilder).isGreaterThan(100_000L);
    assertThat(initialEstimateWithBuilder).isLessThan(50_000_000L);
    assertThat(initialEstimateWithoutBuilder).isGreaterThan(100_000L);
    assertThat(initialEstimateWithoutBuilder).isLessThan(50_000_000L);
  }

  private void setActiveNetworkInfo(NetworkInfo networkInfo) {
    Shadows.shadowOf(connectivityManager).setActiveNetworkInfo(networkInfo);
  }

  private void setNetworkCountryIso(String countryIso) {
    Shadows.shadowOf(telephonyManager).setNetworkCountryIso(countryIso);
  }

  private static long[] simulateTransfers(DefaultBandwidthMeter bandwidthMeter, FakeClock clock) {
    long[] bitrateEstimates = new long[SIMULATED_TRANSFER_COUNT];
    Random random = new Random(/* seed= */ 0);
    DataSource dataSource = new FakeDataSource();
    DataSpec dataSpec = new DataSpec(Uri.parse("https://dummy.com"));
    for (int i = 0; i < SIMULATED_TRANSFER_COUNT; i++) {
      bandwidthMeter.onTransferStart(dataSource, dataSpec, /* isNetwork= */ true);
      clock.advanceTime(random.nextInt(/* bound= */ 5000));
      bandwidthMeter.onBytesTransferred(
          dataSource,
          dataSpec,
          /* isNetwork= */ true,
          /* bytes= */ random.nextInt(5 * 1024 * 1024));
      bandwidthMeter.onTransferEnd(dataSource, dataSpec, /* isNetwork= */ true);
      bitrateEstimates[i] = bandwidthMeter.getBitrateEstimate();
    }
    return bitrateEstimates;
  }
}