Add fake adaptive media period.

This class extends the existing FakeMediaPeriod by using a ChunkSampleStream
with chunks from a FakeChunkSource instead of a FakeSampleStream.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=162916656

testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeAdaptiveMediaPeriod.java

@@ -0,0 +1,118 @@
+/*
+ * 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 com.google.android.exoplayer2.source.AdaptiveMediaSourceEventListener.EventDispatcher;
+import com.google.android.exoplayer2.source.CompositeSequenceableLoader;
+import com.google.android.exoplayer2.source.MediaPeriod;
+import com.google.android.exoplayer2.source.SampleStream;
+import com.google.android.exoplayer2.source.SequenceableLoader;
+import com.google.android.exoplayer2.source.TrackGroupArray;
+import com.google.android.exoplayer2.source.chunk.ChunkSampleStream;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
+import com.google.android.exoplayer2.upstream.Allocator;
+import com.google.android.exoplayer2.util.MimeTypes;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Fake {@link MediaPeriod} that provides tracks from the given {@link TrackGroupArray}. Selecting a
+ * track will give the player a {@link ChunkSampleStream<FakeChunkSource>}.
+ */
+public class FakeAdaptiveMediaPeriod extends FakeMediaPeriod
+    implements SequenceableLoader.Callback<ChunkSampleStream<FakeChunkSource>> {
+
+  private final EventDispatcher eventDispatcher;
+  private final Allocator allocator;
+  private final FakeChunkSource.Factory chunkSourceFactory;
+  private final long durationUs;
+
+  private Callback callback;
+  private ChunkSampleStream<FakeChunkSource>[] sampleStreams;
+  private SequenceableLoader sequenceableLoader;
+
+  public FakeAdaptiveMediaPeriod(TrackGroupArray trackGroupArray, EventDispatcher eventDispatcher,
+      Allocator allocator, FakeChunkSource.Factory chunkSourceFactory, long durationUs) {
+    super(trackGroupArray);
+    this.eventDispatcher = eventDispatcher;
+    this.allocator = allocator;
+    this.chunkSourceFactory = chunkSourceFactory;
+    this.durationUs = durationUs;
+  }
+
+  @Override
+  public void prepare(Callback callback, long positionUs) {
+    super.prepare(callback, positionUs);
+    this.callback = callback;
+  }
+
+  @Override
+  @SuppressWarnings("unchecked")
+  public long selectTracks(TrackSelection[] selections, boolean[] mayRetainStreamFlags,
+      SampleStream[] streams, boolean[] streamResetFlags, long positionUs) {
+    long returnPositionUs = super.selectTracks(selections, mayRetainStreamFlags, streams,
+        streamResetFlags, positionUs);
+    List<ChunkSampleStream<FakeChunkSource>> validStreams = new ArrayList<>();
+    for (SampleStream stream : streams) {
+      if (stream != null) {
+        validStreams.add((ChunkSampleStream<FakeChunkSource>) stream);
+      }
+    }
+    this.sampleStreams = validStreams.toArray(new ChunkSampleStream[validStreams.size()]);
+    this.sequenceableLoader = new CompositeSequenceableLoader(sampleStreams);
+    return returnPositionUs;
+  }
+
+  @Override
+  public long getBufferedPositionUs() {
+    super.getBufferedPositionUs();
+    return sequenceableLoader.getBufferedPositionUs();
+  }
+
+  @Override
+  public long seekToUs(long positionUs) {
+    for (ChunkSampleStream<FakeChunkSource> sampleStream : sampleStreams) {
+      sampleStream.seekToUs(positionUs);
+    }
+    return super.seekToUs(positionUs);
+  }
+
+  @Override
+  public long getNextLoadPositionUs() {
+    super.getNextLoadPositionUs();
+    return sequenceableLoader.getNextLoadPositionUs();
+  }
+
+  @Override
+  public boolean continueLoading(long positionUs) {
+    super.continueLoading(positionUs);
+    return sequenceableLoader.continueLoading(positionUs);
+  }
+
+  @Override
+  protected SampleStream createSampleStream(TrackSelection trackSelection) {
+    FakeChunkSource chunkSource = chunkSourceFactory.createChunkSource(trackSelection, durationUs);
+    return new ChunkSampleStream<>(
+        MimeTypes.getTrackType(trackSelection.getSelectedFormat().sampleMimeType), null,
+        chunkSource, this, allocator, 0, 3, eventDispatcher);
+  }
+
+  @Override
+  public void onContinueLoadingRequested(ChunkSampleStream<FakeChunkSource> source) {
+    callback.onContinueLoadingRequested(this);
+  }
+
+}

testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaPeriod.java

@@ -16,7 +16,6 @@
 package com.google.android.exoplayer2.testutil;
 
 import com.google.android.exoplayer2.C;
-import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.source.MediaPeriod;
 import com.google.android.exoplayer2.source.SampleStream;
 import com.google.android.exoplayer2.source.TrackGroup;
@@ -26,10 +25,10 @@ import java.io.IOException;
 import junit.framework.Assert;
 
 /**
- * Fake {@link MediaPeriod} that provides one track with a given {@link Format}. Selecting that
+ * Fake {@link MediaPeriod} that provides tracks from the given {@link TrackGroupArray}. Selecting
- * track will give the player a {@link FakeSampleStream}.
+ * tracks will give the player {@link FakeSampleStream}s.
  */
-public final class FakeMediaPeriod implements MediaPeriod {
+public class FakeMediaPeriod implements MediaPeriod {
 
   private final TrackGroupArray trackGroupArray;
 
@@ -46,7 +45,6 @@ public final class FakeMediaPeriod implements MediaPeriod {
   @Override
   public void prepare(Callback callback, long positionUs) {
     Assert.assertFalse(preparedPeriod);
-    Assert.assertEquals(0, positionUs);
     preparedPeriod = true;
     callback.onPrepared(this);
   }
@@ -71,8 +69,6 @@ public final class FakeMediaPeriod implements MediaPeriod {
       if (streams[i] != null && (selections[i] == null || !mayRetainStreamFlags[i])) {
         streams[i] = null;
       }
-    }
-    for (int i = 0; i < rendererCount; i++) {
       if (streams[i] == null && selections[i] != null) {
         TrackSelection selection = selections[i];
         Assert.assertTrue(1 <= selection.length());
@@ -81,7 +77,7 @@ public final class FakeMediaPeriod implements MediaPeriod {
         int indexInTrackGroup = selection.getIndexInTrackGroup(selection.getSelectedIndex());
         Assert.assertTrue(0 <= indexInTrackGroup);
         Assert.assertTrue(indexInTrackGroup < trackGroup.length);
-        streams[i] = new FakeSampleStream(selection.getSelectedFormat());
+        streams[i] = createSampleStream(selection);
         streamResetFlags[i] = true;
       }
     }
@@ -123,4 +119,8 @@ public final class FakeMediaPeriod implements MediaPeriod {
     return false;
   }
 
+  protected SampleStream createSampleStream(TrackSelection selection) {
+    return new FakeSampleStream(selection.getSelectedFormat());
+  }
+
 }