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Testing DASH Download Operations in SmartTube ExoPlayer Integration

This test suite validates the DashDownloader component in ExoPlayer, focusing on DASH media downloading functionality and caching behavior. The tests verify download operations, progress tracking, and error handling for DASH streaming content.
Test Coverage Overview

The test suite provides comprehensive coverage of DASH downloading capabilities:
Single and multiple representation downloads
Progressive download validation
Download failure scenarios and recovery
Cache management and removal operations
Download progress tracking
Implementation Analysis

The testing approach uses JUnit with Mockito for mocking dependencies. Tests utilize fake data sources and cache implementations to validate download behaviors in isolation. The suite implements systematic verification of download operations across different DASH manifest configurations.
Technical Details

Key technical components include:
AndroidJUnit4 test runner
Mockito for mocking
FakeDataSet/FakeDataSource for test data
SimpleCache implementation
Custom ProgressListener for download tracking
Best Practices Demonstrated

The test suite exhibits strong testing practices:
Proper test setup/teardown with @Before/@After
Comprehensive edge case coverage
Isolated test scenarios
Clear test method naming
Thorough assertion validation
yuliskov/smarttube

exoplayer-amzn-2.10.6/library/dash/src/test/java/com/google/android/exoplayer2/source/dash/offline/DashDownloaderTest.java
            
/*
 * Copyright (C) 2017 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.source.dash.offline;

import static com.google.android.exoplayer2.source.dash.offline.DashDownloadTestData.TEST_MPD;
import static com.google.android.exoplayer2.source.dash.offline.DashDownloadTestData.TEST_MPD_NO_INDEX;
import static com.google.android.exoplayer2.source.dash.offline.DashDownloadTestData.TEST_MPD_URI;
import static com.google.android.exoplayer2.testutil.CacheAsserts.assertCacheEmpty;
import static com.google.android.exoplayer2.testutil.CacheAsserts.assertCachedData;
import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.fail;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

import android.net.Uri;
import androidx.test.core.app.ApplicationProvider;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import com.google.android.exoplayer2.offline.DefaultDownloaderFactory;
import com.google.android.exoplayer2.offline.DownloadException;
import com.google.android.exoplayer2.offline.DownloadRequest;
import com.google.android.exoplayer2.offline.Downloader;
import com.google.android.exoplayer2.offline.DownloaderConstructorHelper;
import com.google.android.exoplayer2.offline.DownloaderFactory;
import com.google.android.exoplayer2.offline.StreamKey;
import com.google.android.exoplayer2.testutil.CacheAsserts.RequestSet;
import com.google.android.exoplayer2.testutil.FakeDataSet;
import com.google.android.exoplayer2.testutil.FakeDataSource;
import com.google.android.exoplayer2.testutil.FakeDataSource.Factory;
import com.google.android.exoplayer2.testutil.TestUtil;
import com.google.android.exoplayer2.upstream.DataSpec;
import com.google.android.exoplayer2.upstream.DummyDataSource;
import com.google.android.exoplayer2.upstream.cache.Cache;
import com.google.android.exoplayer2.upstream.cache.NoOpCacheEvictor;
import com.google.android.exoplayer2.upstream.cache.SimpleCache;
import com.google.android.exoplayer2.util.Util;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;

/** Unit tests for {@link DashDownloader}. */
@RunWith(AndroidJUnit4.class)
public class DashDownloaderTest {

  private SimpleCache cache;
  private File tempFolder;
  private ProgressListener progressListener;

  @Before
  public void setUp() throws Exception {
    MockitoAnnotations.initMocks(this);
    tempFolder =
        Util.createTempDirectory(ApplicationProvider.getApplicationContext(), "ExoPlayerTest");
    cache = new SimpleCache(tempFolder, new NoOpCacheEvictor());
    progressListener = new ProgressListener();
  }

  @After
  public void tearDown() {
    Util.recursiveDelete(tempFolder);
  }

  @Test
  public void testCreateWithDefaultDownloaderFactory() {
    DownloaderConstructorHelper constructorHelper =
        new DownloaderConstructorHelper(Mockito.mock(Cache.class), DummyDataSource.FACTORY);
    DownloaderFactory factory = new DefaultDownloaderFactory(constructorHelper);

    Downloader downloader =
        factory.createDownloader(
            new DownloadRequest(
                "id",
                DownloadRequest.TYPE_DASH,
                Uri.parse("https://www.test.com/download"),
                Collections.singletonList(new StreamKey(/* groupIndex= */ 0, /* trackIndex= */ 0)),
                /* customCacheKey= */ null,
                /* data= */ null));
    assertThat(downloader).isInstanceOf(DashDownloader.class);
  }

  @Test
  public void testDownloadRepresentation() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD)
            .setRandomData("audio_init_data", 10)
            .setRandomData("audio_segment_1", 4)
            .setRandomData("audio_segment_2", 5)
            .setRandomData("audio_segment_3", 6);

    DashDownloader dashDownloader = getDashDownloader(fakeDataSet, new StreamKey(0, 0, 0));
    dashDownloader.download(progressListener);
    assertCachedData(cache, new RequestSet(fakeDataSet).useBoundedDataSpecFor("audio_init_data"));
  }

  @Test
  public void testDownloadRepresentationInSmallParts() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD)
            .setRandomData("audio_init_data", 10)
            .newData("audio_segment_1")
            .appendReadData(TestUtil.buildTestData(10))
            .appendReadData(TestUtil.buildTestData(10))
            .appendReadData(TestUtil.buildTestData(10))
            .endData()
            .setRandomData("audio_segment_2", 5)
            .setRandomData("audio_segment_3", 6);

    DashDownloader dashDownloader = getDashDownloader(fakeDataSet, new StreamKey(0, 0, 0));
    dashDownloader.download(progressListener);
    assertCachedData(cache, new RequestSet(fakeDataSet).useBoundedDataSpecFor("audio_init_data"));
  }

  @Test
  public void testDownloadRepresentations() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD)
            .setRandomData("audio_init_data", 10)
            .setRandomData("audio_segment_1", 4)
            .setRandomData("audio_segment_2", 5)
            .setRandomData("audio_segment_3", 6)
            .setRandomData("text_segment_1", 1)
            .setRandomData("text_segment_2", 2)
            .setRandomData("text_segment_3", 3);

    DashDownloader dashDownloader =
        getDashDownloader(fakeDataSet, new StreamKey(0, 0, 0), new StreamKey(0, 1, 0));
    dashDownloader.download(progressListener);
    assertCachedData(cache, new RequestSet(fakeDataSet).useBoundedDataSpecFor("audio_init_data"));
  }

  @Test
  public void testDownloadAllRepresentations() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD)
            .setRandomData("audio_init_data", 10)
            .setRandomData("audio_segment_1", 4)
            .setRandomData("audio_segment_2", 5)
            .setRandomData("audio_segment_3", 6)
            .setRandomData("text_segment_1", 1)
            .setRandomData("text_segment_2", 2)
            .setRandomData("text_segment_3", 3)
            .setRandomData("period_2_segment_1", 1)
            .setRandomData("period_2_segment_2", 2)
            .setRandomData("period_2_segment_3", 3);

    DashDownloader dashDownloader = getDashDownloader(fakeDataSet);
    dashDownloader.download(progressListener);
    assertCachedData(cache, new RequestSet(fakeDataSet).useBoundedDataSpecFor("audio_init_data"));
  }

  @Test
  public void testProgressiveDownload() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD)
            .setRandomData("audio_init_data", 10)
            .setRandomData("audio_segment_1", 4)
            .setRandomData("audio_segment_2", 5)
            .setRandomData("audio_segment_3", 6)
            .setRandomData("text_segment_1", 1)
            .setRandomData("text_segment_2", 2)
            .setRandomData("text_segment_3", 3);
    FakeDataSource fakeDataSource = new FakeDataSource(fakeDataSet);
    Factory factory = mock(Factory.class);
    when(factory.createDataSource()).thenReturn(fakeDataSource);

    DashDownloader dashDownloader =
        getDashDownloader(factory, new StreamKey(0, 0, 0), new StreamKey(0, 1, 0));
    dashDownloader.download(progressListener);

    DataSpec[] openedDataSpecs = fakeDataSource.getAndClearOpenedDataSpecs();
    assertThat(openedDataSpecs.length).isEqualTo(8);
    assertThat(openedDataSpecs[0].uri).isEqualTo(TEST_MPD_URI);
    assertThat(openedDataSpecs[1].uri.getPath()).isEqualTo("audio_init_data");
    assertThat(openedDataSpecs[2].uri.getPath()).isEqualTo("audio_segment_1");
    assertThat(openedDataSpecs[3].uri.getPath()).isEqualTo("text_segment_1");
    assertThat(openedDataSpecs[4].uri.getPath()).isEqualTo("audio_segment_2");
    assertThat(openedDataSpecs[5].uri.getPath()).isEqualTo("text_segment_2");
    assertThat(openedDataSpecs[6].uri.getPath()).isEqualTo("audio_segment_3");
    assertThat(openedDataSpecs[7].uri.getPath()).isEqualTo("text_segment_3");
  }

  @Test
  public void testProgressiveDownloadSeparatePeriods() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD)
            .setRandomData("audio_init_data", 10)
            .setRandomData("audio_segment_1", 4)
            .setRandomData("audio_segment_2", 5)
            .setRandomData("audio_segment_3", 6)
            .setRandomData("period_2_segment_1", 1)
            .setRandomData("period_2_segment_2", 2)
            .setRandomData("period_2_segment_3", 3);
    FakeDataSource fakeDataSource = new FakeDataSource(fakeDataSet);
    Factory factory = mock(Factory.class);
    when(factory.createDataSource()).thenReturn(fakeDataSource);

    DashDownloader dashDownloader =
        getDashDownloader(factory, new StreamKey(0, 0, 0), new StreamKey(1, 0, 0));
    dashDownloader.download(progressListener);

    DataSpec[] openedDataSpecs = fakeDataSource.getAndClearOpenedDataSpecs();
    assertThat(openedDataSpecs.length).isEqualTo(8);
    assertThat(openedDataSpecs[0].uri).isEqualTo(TEST_MPD_URI);
    assertThat(openedDataSpecs[1].uri.getPath()).isEqualTo("audio_init_data");
    assertThat(openedDataSpecs[2].uri.getPath()).isEqualTo("audio_segment_1");
    assertThat(openedDataSpecs[3].uri.getPath()).isEqualTo("audio_segment_2");
    assertThat(openedDataSpecs[4].uri.getPath()).isEqualTo("audio_segment_3");
    assertThat(openedDataSpecs[5].uri.getPath()).isEqualTo("period_2_segment_1");
    assertThat(openedDataSpecs[6].uri.getPath()).isEqualTo("period_2_segment_2");
    assertThat(openedDataSpecs[7].uri.getPath()).isEqualTo("period_2_segment_3");
  }

  @Test
  public void testDownloadRepresentationFailure() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD)
            .setRandomData("audio_init_data", 10)
            .setRandomData("audio_segment_1", 4)
            .newData("audio_segment_2")
            .appendReadData(TestUtil.buildTestData(2))
            .appendReadError(new IOException())
            .appendReadData(TestUtil.buildTestData(3))
            .endData()
            .setRandomData("audio_segment_3", 6);

    DashDownloader dashDownloader = getDashDownloader(fakeDataSet, new StreamKey(0, 0, 0));
    try {
      dashDownloader.download(progressListener);
      fail();
    } catch (IOException e) {
      // Expected.
    }
    dashDownloader.download(progressListener);
    assertCachedData(cache, new RequestSet(fakeDataSet).useBoundedDataSpecFor("audio_init_data"));
  }

  @Test
  public void testCounters() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD)
            .setRandomData("audio_init_data", 10)
            .setRandomData("audio_segment_1", 4)
            .newData("audio_segment_2")
            .appendReadData(TestUtil.buildTestData(2))
            .appendReadError(new IOException())
            .appendReadData(TestUtil.buildTestData(3))
            .endData()
            .setRandomData("audio_segment_3", 6);

    DashDownloader dashDownloader = getDashDownloader(fakeDataSet, new StreamKey(0, 0, 0));

    try {
      dashDownloader.download(progressListener);
      fail();
    } catch (IOException e) {
      // Failure expected after downloading init data, segment 1 and 2 bytes in segment 2.
    }
    progressListener.assertBytesDownloaded(10 + 4 + 2);

    dashDownloader.download(progressListener);
    progressListener.assertBytesDownloaded(10 + 4 + 5 + 6);
  }

  @Test
  public void testRemove() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD)
            .setRandomData("audio_init_data", 10)
            .setRandomData("audio_segment_1", 4)
            .setRandomData("audio_segment_2", 5)
            .setRandomData("audio_segment_3", 6)
            .setRandomData("text_segment_1", 1)
            .setRandomData("text_segment_2", 2)
            .setRandomData("text_segment_3", 3);

    DashDownloader dashDownloader =
        getDashDownloader(fakeDataSet, new StreamKey(0, 0, 0), new StreamKey(0, 1, 0));
    dashDownloader.download(progressListener);
    dashDownloader.remove();
    assertCacheEmpty(cache);
  }

  @Test
  public void testRepresentationWithoutIndex() throws Exception {
    FakeDataSet fakeDataSet =
        new FakeDataSet()
            .setData(TEST_MPD_URI, TEST_MPD_NO_INDEX)
            .setRandomData("test_segment_1", 4);

    DashDownloader dashDownloader = getDashDownloader(fakeDataSet, new StreamKey(0, 0, 0));
    try {
      dashDownloader.download(progressListener);
      fail();
    } catch (DownloadException e) {
      // Expected.
    }
    dashDownloader.remove();
    assertCacheEmpty(cache);
  }

  private DashDownloader getDashDownloader(FakeDataSet fakeDataSet, StreamKey... keys) {
    return getDashDownloader(new Factory().setFakeDataSet(fakeDataSet), keys);
  }

  private DashDownloader getDashDownloader(Factory factory, StreamKey... keys) {
    return new DashDownloader(
        TEST_MPD_URI, keysList(keys), new DownloaderConstructorHelper(cache, factory));
  }

  private static ArrayList<StreamKey> keysList(StreamKey... keys) {
    ArrayList<StreamKey> keysList = new ArrayList<>();
    Collections.addAll(keysList, keys);
    return keysList;
  }

  private static final class ProgressListener implements Downloader.ProgressListener {

    private long bytesDownloaded;

    @Override
    public void onProgress(long contentLength, long bytesDownloaded, float percentDownloaded) {
      this.bytesDownloaded = bytesDownloaded;
    }

    public void assertBytesDownloaded(long bytesDownloaded) {
      assertThat(this.bytesDownloaded).isEqualTo(bytesDownloaded);
    }
  }
}