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Testing Adaptive Streaming Data Management in SmartTube

This test suite validates the FakeAdaptiveDataSet class implementation in ExoPlayer, focusing on adaptive streaming data simulation and chunk management. It ensures proper handling of video formats, chunk durations, and data distribution for testing adaptive streaming scenarios.

Test Coverage Overview

The test suite provides comprehensive coverage of adaptive streaming data management:

Chunk duration and timing verification
Format-specific data generation and validation
Chunk size distribution analysis
Edge case handling for trailing chunks

Implementation Analysis

The testing approach utilizes JUnit with AndroidJUnit4 runner, implementing systematic validation of adaptive streaming components. Tests verify chunk duration calculations, data distribution patterns, and format-specific bitrate handling using mock video formats.

Technical Details

Testing infrastructure includes:

JUnit test framework with AndroidJUnit4 runner
ExoPlayer’s Format and TrackGroup utilities
Custom FakeAdaptiveDataSet implementation
Statistical validation tools for size distribution

Best Practices Demonstrated

The test suite exemplifies robust testing practices:

Systematic validation of component behaviors
Statistical verification of data distributions
Comprehensive edge case coverage
Clear test organization and separation of concerns

yuliskov/smarttube

exoplayer-amzn-2.10.6/testutils/src/test/java/com/google/android/exoplayer2/testutil/FakeAdaptiveDataSetTest.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.testutil;

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

import androidx.test.ext.junit.runners.AndroidJUnit4;
import com.google.android.exoplayer2.C;
import com.google.android.exoplayer2.Format;
import com.google.android.exoplayer2.source.TrackGroup;
import com.google.android.exoplayer2.testutil.FakeDataSet.FakeData;
import com.google.android.exoplayer2.testutil.FakeDataSet.FakeData.Segment;
import com.google.android.exoplayer2.util.MimeTypes;
import java.util.List;
import java.util.Random;
import org.junit.Test;
import org.junit.runner.RunWith;

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

  private static final Format[] TEST_FORMATS = {
    Format.createVideoSampleFormat(
        null,
        MimeTypes.VIDEO_H264,
        null,
        1000000,
        Format.NO_VALUE,
        1280,
        720,
        Format.NO_VALUE,
        null,
        null),
    Format.createVideoSampleFormat(
        null,
        MimeTypes.VIDEO_H264,
        null,
        300000,
        Format.NO_VALUE,
        640,
        360,
        Format.NO_VALUE,
        null,
        null)
  };
  private static final TrackGroup TRACK_GROUP = new TrackGroup(TEST_FORMATS);

  @Test
  public void testAdaptiveDataSet() {
    long chunkDuration = 2 * C.MICROS_PER_SECOND;
    FakeAdaptiveDataSet dataSet =
        new FakeAdaptiveDataSet(
            TRACK_GROUP, 10 * C.MICROS_PER_SECOND, chunkDuration, 0.0, new Random(0));
    assertThat(dataSet.getAllData().size()).isEqualTo(TEST_FORMATS.length);
    assertThat(dataSet.getUri(0).equals(dataSet.getUri(1))).isFalse();
    assertThat(dataSet.getChunkCount()).isEqualTo(5);
    assertThat(dataSet.getChunkIndexByPosition(4 * C.MICROS_PER_SECOND)).isEqualTo(2);
    assertThat(dataSet.getChunkIndexByPosition(9 * C.MICROS_PER_SECOND)).isEqualTo(4);
    for (int i = 0; i < dataSet.getChunkCount(); i++) {
      assertThat(dataSet.getChunkDuration(i)).isEqualTo(chunkDuration);
    }
    assertChunkData(dataSet, chunkDuration);
  }

  @Test
  public void testAdaptiveDataSetTrailingSmallChunk() {
    long chunkDuration = 3 * C.MICROS_PER_SECOND;
    FakeAdaptiveDataSet dataSet =
        new FakeAdaptiveDataSet(
            TRACK_GROUP, 10 * C.MICROS_PER_SECOND, chunkDuration, 0.0, new Random(0));
    assertThat(dataSet.getAllData().size()).isEqualTo(TEST_FORMATS.length);
    assertThat(dataSet.getUri(0).equals(dataSet.getUri(1))).isFalse();
    assertThat(dataSet.getChunkCount()).isEqualTo(4);
    assertThat(dataSet.getChunkIndexByPosition(4 * C.MICROS_PER_SECOND)).isEqualTo(1);
    assertThat(dataSet.getChunkIndexByPosition(9 * C.MICROS_PER_SECOND)).isEqualTo(3);
    for (int i = 0; i < dataSet.getChunkCount() - 1; i++) {
      assertThat(dataSet.getChunkDuration(i)).isEqualTo(chunkDuration);
    }
    assertThat(dataSet.getChunkDuration(3)).isEqualTo(1 * C.MICROS_PER_SECOND);
    assertChunkData(dataSet, chunkDuration);
  }

  @Test
  public void testAdaptiveDataSetChunkSizeDistribution() {
    double expectedStdDev = 4.0;
    FakeAdaptiveDataSet dataSet =
        new FakeAdaptiveDataSet(
            TRACK_GROUP,
            100000 * C.MICROS_PER_SECOND,
            1 * C.MICROS_PER_SECOND,
            expectedStdDev,
            new Random(0));
    for (int i = 0; i < TEST_FORMATS.length; i++) {
      FakeData data = dataSet.getData(dataSet.getUri(i));
      double mean = computeSegmentSizeMean(data.getSegments());
      double stddev = computeSegmentSizeStdDev(data.getSegments(), mean);
      double relativePercentStdDev = stddev / mean * 100.0;
      assertThat(relativePercentStdDev).isWithin(0.02).of(expectedStdDev);
      assertThat(mean * 8 / TEST_FORMATS[i].bitrate).isWithin(0.01).of(1.0);
    }
  }

  private void assertChunkData(FakeAdaptiveDataSet dataSet, long chunkDuration) {
    for (int i = 0; i < dataSet.getChunkCount(); i++) {
      assertThat(dataSet.getStartTime(i)).isEqualTo(chunkDuration * i);
    }
    for (int s = 0; s < TEST_FORMATS.length; s++) {
      FakeData data = dataSet.getData(dataSet.getUri(s));
      assertThat(data.getSegments().size()).isEqualTo(dataSet.getChunkCount());
      for (int i = 0; i < data.getSegments().size(); i++) {
        long expectedLength =
            TEST_FORMATS[s].bitrate * dataSet.getChunkDuration(i) / (8 * C.MICROS_PER_SECOND);
        assertThat(data.getSegments().get(i).length).isEqualTo(expectedLength);
      }
    }
  }

  private static double computeSegmentSizeMean(List<Segment> segments) {
    double totalSize = 0.0;
    for (Segment segment : segments) {
      totalSize += segment.length;
    }
    return totalSize / segments.size();
  }

  private static double computeSegmentSizeStdDev(List<Segment> segments, double mean) {
    double totalSquaredSize = 0.0;
    for (Segment segment : segments) {
      totalSquaredSize += (double) segment.length * segment.length;
    }
    return Math.sqrt(totalSquaredSize / segments.size() - mean * mean);
  }
}