Start fixing nullness in testutil

PiperOrigin-RevId: 292340530

library/core/src/main/java/com/google/android/exoplayer2/source/chunk/SingleSampleMediaChunk.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source.chunk;
 
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.extractor.DefaultExtractorInput;
@@ -54,7 +55,7 @@ public final class SingleSampleMediaChunk extends BaseMediaChunk {
       DataSpec dataSpec,
       Format trackFormat,
       int trackSelectionReason,
-      Object trackSelectionData,
+      @Nullable Object trackSelectionData,
       long startTimeUs,
       long endTimeUs,
       long chunkIndex,

library/core/src/test/java/com/google/android/exoplayer2/ExoPlayerTest.java

@@ -821,7 +821,8 @@ public final class ExoPlayerTest {
         new FakeMediaSource(timeline, Builder.VIDEO_FORMAT, Builder.AUDIO_FORMAT);
     FakeRenderer videoRenderer = new FakeRenderer(Builder.VIDEO_FORMAT);
     FakeRenderer audioRenderer = new FakeRenderer(Builder.AUDIO_FORMAT);
-    final FakeTrackSelector trackSelector = new FakeTrackSelector(/* reuse track selection */ true);
+    final FakeTrackSelector trackSelector =
+        new FakeTrackSelector(/* mayReuseTrackSelection= */ true);
     ActionSchedule disableTrackAction =
         new ActionSchedule.Builder("testReuseTrackSelection")
             .pause()

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

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.testutil;
 
 import com.google.android.exoplayer2.util.HandlerWrapper;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /**
  * {@link FakeClock} extension which automatically advances time whenever an empty message is
@@ -25,7 +26,7 @@ import com.google.android.exoplayer2.util.HandlerWrapper;
  */
 public final class AutoAdvancingFakeClock extends FakeClock {
 
-  private HandlerWrapper autoAdvancingHandler;
+  private @MonotonicNonNull HandlerWrapper autoAdvancingHandler;
 
   public AutoAdvancingFakeClock() {
     super(/* initialTimeMs= */ 0);

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

@@ -21,6 +21,7 @@ import android.content.Context;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.audio.AudioSink;
 import com.google.android.exoplayer2.audio.ForwardingAudioSink;
+import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 import java.io.File;
 import java.io.IOException;
@@ -122,7 +123,7 @@ public final class CapturingAudioSink extends ForwardingAudioSink implements Dum
     if (WRITE_DUMP) {
       File directory = context.getExternalFilesDir(null);
       File file = new File(directory, dumpFile);
-      file.getParentFile().mkdirs();
+      Assertions.checkStateNotNull(file.getParentFile()).mkdirs();
       PrintWriter out = new PrintWriter(file);
       out.print(actual);
       out.close();

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

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.testutil;
 
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import java.util.Arrays;
 import java.util.Locale;
@@ -44,7 +45,7 @@ public final class Dumper {
     sb = new StringBuilder();
   }
 
-  public Dumper add(String field, Object value) {
+  public Dumper add(String field, @Nullable Object value) {
     return addString(field + " = " + value + '\n');
   }
 
@@ -53,8 +54,13 @@ public final class Dumper {
     return this;
   }
 
-  public Dumper add(String field, byte[] value) {
+  public Dumper add(String field, @Nullable byte[] value) {
-    String string = String.format(Locale.US, "%s = length %d, hash %X\n", field, value.length,
+    String string =
+        String.format(
+            Locale.US,
+            "%s = length %d, hash %X\n",
+            field,
+            value == null ? 0 : value.length,
             Arrays.hashCode(value));
     return addString(string);
   }

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

@@ -209,7 +209,7 @@ public final class ExtractorAsserts {
     }
 
     // If the SeekMap is seekable, test seeking in the stream.
-    SeekMap seekMap = extractorOutput.seekMap;
+    SeekMap seekMap = Assertions.checkNotNull(extractorOutput.seekMap);
     if (seekMap.isSeekable()) {
       long durationUs = seekMap.getDurationUs();
       for (int j = 0; j < 4; j++) {
@@ -361,7 +361,7 @@ public final class ExtractorAsserts {
     int i = fileName.lastIndexOf('/');
     String path = i >= 0 ? fileName.substring(0, i) : "";
     String file = i >= 0 ? fileName.substring(i + 1) : fileName;
-    return Arrays.asList(context.getResources().getAssets().list(path)).contains(file);
+    String[] assets = context.getResources().getAssets().list(path);
+    return assets != null && Arrays.asList(assets).contains(file);
   }
-
 }

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

@@ -23,6 +23,7 @@ import com.google.android.exoplayer2.source.chunk.BaseMediaChunkIterator;
 import com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
 import com.google.android.exoplayer2.testutil.FakeDataSet.FakeData.Segment;
 import com.google.android.exoplayer2.upstream.DataSpec;
+import com.google.android.exoplayer2.util.Util;
 import java.util.Random;
 
 /**
@@ -92,7 +93,7 @@ public final class FakeAdaptiveDataSet extends FakeDataSet {
       checkInBounds();
       String uri = dataSet.getUri(trackGroupIndex);
       int chunkIndex = (int) getCurrentIndex();
-      Segment fakeDataChunk = dataSet.getData(uri).getSegments().get(chunkIndex);
+      Segment fakeDataChunk = Util.castNonNull(dataSet.getData(uri)).getSegments().get(chunkIndex);
       return new DataSpec(
           Uri.parse(uri), fakeDataChunk.byteOffset, fakeDataChunk.length, /* key= */ null);
     }

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

@@ -28,9 +28,12 @@ import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.Allocator;
 import com.google.android.exoplayer2.upstream.DefaultLoadErrorHandlingPolicy;
 import com.google.android.exoplayer2.upstream.TransferListener;
+import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.MimeTypes;
 import java.util.ArrayList;
 import java.util.List;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /**
  * Fake {@link MediaPeriod} that provides tracks from the given {@link TrackGroupArray}. Selecting a
@@ -44,7 +47,7 @@ public class FakeAdaptiveMediaPeriod extends FakeMediaPeriod
   @Nullable private final TransferListener transferListener;
   private final long durationUs;
 
-  private Callback callback;
+  @MonotonicNonNull private Callback callback;
   private ChunkSampleStream<FakeChunkSource>[] sampleStreams;
   private SequenceableLoader sequenceableLoader;
 
@@ -81,9 +84,9 @@ public class FakeAdaptiveMediaPeriod extends FakeMediaPeriod
   @Override
   @SuppressWarnings("unchecked")
   public long selectTracks(
-      TrackSelection[] selections,
+      @NullableType TrackSelection[] selections,
       boolean[] mayRetainStreamFlags,
-      SampleStream[] streams,
+      @NullableType SampleStream[] streams,
       boolean[] streamResetFlags,
       long positionUs) {
     long returnPositionUs = super.selectTracks(selections, mayRetainStreamFlags, streams,
@@ -94,7 +97,8 @@ public class FakeAdaptiveMediaPeriod extends FakeMediaPeriod
         validStreams.add((ChunkSampleStream<FakeChunkSource>) stream);
       }
     }
-    this.sampleStreams = validStreams.toArray(newSampleStreamArray(validStreams.size()));
+    sampleStreams = newSampleStreamArray(validStreams.size());
+    validStreams.toArray(sampleStreams);
     this.sequenceableLoader = new CompositeSequenceableLoader(sampleStreams);
     return returnPositionUs;
   }
@@ -162,7 +166,7 @@ public class FakeAdaptiveMediaPeriod extends FakeMediaPeriod
 
   @Override
   public void onContinueLoadingRequested(ChunkSampleStream<FakeChunkSource> source) {
-    callback.onContinueLoadingRequested(this);
+    Assertions.checkStateNotNull(callback).onContinueLoadingRequested(this);
   }
 
   // We won't assign the array to a variable that erases the generic type, and then write into it.

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

@@ -18,6 +18,7 @@ package com.google.android.exoplayer2.testutil;
 import android.os.Handler.Callback;
 import android.os.Looper;
 import android.os.Message;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.util.Clock;
 import com.google.android.exoplayer2.util.HandlerWrapper;
 import java.util.ArrayList;
@@ -90,7 +91,7 @@ public class FakeClock implements Clock {
   }
 
   @Override
-  public HandlerWrapper createHandler(Looper looper, Callback callback) {
+  public HandlerWrapper createHandler(Looper looper, @Nullable Callback callback) {
     return new ClockHandler(looper, callback);
   }
 
@@ -119,7 +120,7 @@ public class FakeClock implements Clock {
 
     private final long postTime;
     private final HandlerWrapper handler;
-    private final Runnable runnable;
+    @Nullable private final Runnable runnable;
     private final int message;
 
     public HandlerMessageData(long postTime, HandlerWrapper handler, Runnable runnable) {
@@ -155,7 +156,7 @@ public class FakeClock implements Clock {
 
     private final android.os.Handler handler;
 
-    public ClockHandler(Looper looper, Callback callback) {
+    public ClockHandler(Looper looper, @Nullable Callback callback) {
       handler = new android.os.Handler(looper, callback);
     }
 
@@ -170,7 +171,7 @@ public class FakeClock implements Clock {
     }
 
     @Override
-    public Message obtainMessage(int what, Object obj) {
+    public Message obtainMessage(int what, @Nullable Object obj) {
       return handler.obtainMessage(what, obj);
     }
 
@@ -180,7 +181,7 @@ public class FakeClock implements Clock {
     }
 
     @Override
-    public Message obtainMessage(int what, int arg1, int arg2, Object obj) {
+    public Message obtainMessage(int what, int arg1, int arg2, @Nullable Object obj) {
       return handler.obtainMessage(what, arg1, arg2, obj);
     }
 
@@ -200,7 +201,7 @@ public class FakeClock implements Clock {
     }
 
     @Override
-    public void removeCallbacksAndMessages(Object token) {
+    public void removeCallbacksAndMessages(@Nullable Object token) {
       handler.removeCallbacksAndMessages(token);
     }
 

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

@@ -89,24 +89,28 @@ public class FakeDataSet {
       public boolean exceptionCleared;
       public int bytesRead;
 
-      private Segment(byte[] data, Segment previousSegment) {
+      private Segment(byte[] data, @Nullable Segment previousSegment) {
         this(data, data.length, null, null, previousSegment);
       }
 
-      private Segment(int length, Segment previousSegment) {
+      private Segment(int length, @Nullable Segment previousSegment) {
         this(null, length, null, null, previousSegment);
       }
 
-      private Segment(IOException exception, Segment previousSegment) {
+      private Segment(IOException exception, @Nullable Segment previousSegment) {
         this(null, 0, exception, null, previousSegment);
       }
 
-      private Segment(Runnable action, Segment previousSegment) {
+      private Segment(Runnable action, @Nullable Segment previousSegment) {
         this(null, 0, null, action, previousSegment);
       }
 
-      private Segment(@Nullable byte[] data, int length, @Nullable IOException exception,
+      private Segment(
-          @Nullable Runnable action, Segment previousSegment) {
+          @Nullable byte[] data,
+          int length,
+          @Nullable IOException exception,
+          @Nullable Runnable action,
+          @Nullable Segment previousSegment) {
         this.exception = exception;
         this.action = action;
         this.data = data;
@@ -125,16 +129,17 @@ public class FakeDataSet {
 
     }
 
-    /** Uri of the data or null if this is the default FakeData. */
-    public final Uri uri;
-    private final ArrayList<Segment> segments;
     private final FakeDataSet dataSet;
+    /** Uri of the data or null if this is the default FakeData. */
+    @Nullable public final Uri uri;
+
+    private final ArrayList<Segment> segments;
     private boolean simulateUnknownLength;
 
-    private FakeData(FakeDataSet dataSet, Uri uri) {
+    private FakeData(FakeDataSet dataSet, @Nullable Uri uri) {
+      this.dataSet = dataSet;
       this.uri = uri;
       this.segments = new ArrayList<>();
-      this.dataSet = dataSet;
     }
 
     /** Returns the {@link FakeDataSet} this FakeData belongs to. */
@@ -157,7 +162,7 @@ public class FakeDataSet {
      * Appends to the underlying data.
      */
     public FakeData appendReadData(byte[] data) {
-      Assertions.checkState(data != null && data.length > 0);
+      Assertions.checkState(data.length > 0);
       segments.add(new Segment(data, getLastSegment()));
       return this;
     }
@@ -213,6 +218,7 @@ public class FakeDataSet {
       return simulateUnknownLength;
     }
 
+    @Nullable
     private Segment getLastSegment() {
       int count = segments.size();
       return count > 0 ? segments.get(count - 1) : null;
@@ -221,7 +227,7 @@ public class FakeDataSet {
   }
 
   private final HashMap<Uri, FakeData> dataMap;
-  private FakeData defaultData;
+  @Nullable private FakeData defaultData;
 
   public FakeDataSet() {
     dataMap = new HashMap<>();
@@ -266,13 +272,15 @@ public class FakeDataSet {
   }
 
   /** Returns the data for the given {@code uri}, or {@code defaultData} if no data is set. */
+  @Nullable
   public FakeData getData(String uri) {
     return getData(Uri.parse(uri));
   }
 
   /** Returns the data for the given {@code uri}, or {@code defaultData} if no data is set. */
+  @Nullable
   public FakeData getData(Uri uri) {
-    FakeData data = dataMap.get(uri);
+    @Nullable FakeData data = dataMap.get(uri);
     return data != null ? data : defaultData;
   }
 

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

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.testutil;
 
 import android.net.Uri;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.testutil.FakeDataSet.FakeData;
 import com.google.android.exoplayer2.testutil.FakeDataSet.FakeData.Segment;
@@ -24,8 +25,10 @@ import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSourceException;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
 import java.util.ArrayList;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /**
  * A fake {@link DataSource} capable of simulating various scenarios. It uses a {@link FakeDataSet}
@@ -38,7 +41,7 @@ public class FakeDataSource extends BaseDataSource {
    */
   public static class Factory implements DataSource.Factory {
 
-    protected FakeDataSet fakeDataSet;
+    protected @MonotonicNonNull FakeDataSet fakeDataSet;
     protected boolean isNetwork;
 
     public final Factory setFakeDataSet(FakeDataSet fakeDataSet) {
@@ -53,17 +56,17 @@ public class FakeDataSource extends BaseDataSource {
 
     @Override
     public FakeDataSource createDataSource() {
-      return new FakeDataSource(fakeDataSet, isNetwork);
+      return new FakeDataSource(Assertions.checkStateNotNull(fakeDataSet), isNetwork);
     }
   }
 
   private final FakeDataSet fakeDataSet;
   private final ArrayList<DataSpec> openedDataSpecs;
 
-  private Uri uri;
+  @Nullable private Uri uri;
   private boolean openCalled;
   private boolean sourceOpened;
-  private FakeData fakeData;
+  @Nullable private FakeData fakeData;
   private int currentSegmentIndex;
   private long bytesRemaining;
 
@@ -96,10 +99,11 @@ public class FakeDataSource extends BaseDataSource {
     openedDataSpecs.add(dataSpec);
 
     transferInitializing(dataSpec);
-    fakeData = fakeDataSet.getData(uri.toString());
+    FakeData fakeData = fakeDataSet.getData(dataSpec.uri.toString());
     if (fakeData == null) {
       throw new IOException("Data not found: " + dataSpec.uri);
     }
+    this.fakeData = fakeData;
 
     long totalLength = 0;
     for (Segment segment : fakeData.getSegments()) {
@@ -145,6 +149,7 @@ public class FakeDataSource extends BaseDataSource {
   public final int read(byte[] buffer, int offset, int readLength) throws IOException {
     Assertions.checkState(sourceOpened);
     while (true) {
+      FakeData fakeData = Util.castNonNull(this.fakeData);
       if (currentSegmentIndex == fakeData.getSegments().size() || bytesRemaining == 0) {
         return C.RESULT_END_OF_INPUT;
       }
@@ -152,13 +157,13 @@ public class FakeDataSource extends BaseDataSource {
       if (current.isErrorSegment()) {
         if (!current.exceptionCleared) {
           current.exceptionThrown = true;
-          throw (IOException) current.exception.fillInStackTrace();
+          throw (IOException) Util.castNonNull(current.exception).fillInStackTrace();
         } else {
           currentSegmentIndex++;
         }
       } else if (current.isActionSegment()) {
         currentSegmentIndex++;
-        current.action.run();
+        Util.castNonNull(current.action).run();
       } else {
         // Read at most bytesRemaining.
         readLength = (int) Math.min(readLength, bytesRemaining);
@@ -181,13 +186,14 @@ public class FakeDataSource extends BaseDataSource {
     }
   }
 
+  @Nullable
   @Override
   public final Uri getUri() {
     return uri;
   }
 
   @Override
-  public final void close() throws IOException {
+  public final void close() {
     Assertions.checkState(openCalled);
     openCalled = false;
     uri = null;

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

@@ -20,12 +20,15 @@ import static com.google.common.truth.Truth.assertWithMessage;
 
 import android.content.Context;
 import android.util.SparseArray;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.extractor.ExtractorOutput;
 import com.google.android.exoplayer2.extractor.SeekMap;
+import com.google.android.exoplayer2.util.Assertions;
 import java.io.File;
 import java.io.IOException;
 import java.io.PrintWriter;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /**
  * A fake {@link ExtractorOutput}.
@@ -45,7 +48,7 @@ public final class FakeExtractorOutput implements ExtractorOutput, Dumper.Dumpab
 
   public int numberOfTracks;
   public boolean tracksEnded;
-  public SeekMap seekMap;
+  public @MonotonicNonNull SeekMap seekMap;
 
   public FakeExtractorOutput() {
     trackOutputs = new SparseArray<>();
@@ -53,7 +56,7 @@ public final class FakeExtractorOutput implements ExtractorOutput, Dumper.Dumpab
 
   @Override
   public FakeTrackOutput track(int id, int type) {
-    FakeTrackOutput output = trackOutputs.get(id);
+    @Nullable FakeTrackOutput output = trackOutputs.get(id);
     if (output == null) {
       assertThat(tracksEnded).isFalse();
       numberOfTracks++;
@@ -99,10 +102,11 @@ public final class FakeExtractorOutput implements ExtractorOutput, Dumper.Dumpab
       assertThat(seekMap).isNull();
     } else {
       // TODO: Bulk up this check if possible.
-      assertThat(seekMap).isNotNull();
+      SeekMap expectedSeekMap = Assertions.checkNotNull(expected.seekMap);
-      assertThat(seekMap.getClass()).isEqualTo(expected.seekMap.getClass());
+      SeekMap seekMap = Assertions.checkNotNull(this.seekMap);
-      assertThat(seekMap.isSeekable()).isEqualTo(expected.seekMap.isSeekable());
+      assertThat(seekMap.getClass()).isEqualTo(expectedSeekMap.getClass());
-      assertThat(seekMap.getSeekPoints(0)).isEqualTo(expected.seekMap.getSeekPoints(0));
+      assertThat(seekMap.isSeekable()).isEqualTo(expectedSeekMap.isSeekable());
+      assertThat(seekMap.getSeekPoints(0)).isEqualTo(expectedSeekMap.getSeekPoints(0));
     }
     for (int i = 0; i < numberOfTracks; i++) {
       assertThat(trackOutputs.keyAt(i)).isEqualTo(expected.trackOutputs.keyAt(i));
@@ -125,7 +129,7 @@ public final class FakeExtractorOutput implements ExtractorOutput, Dumper.Dumpab
     if (WRITE_DUMP) {
       File file = new File(System.getProperty("user.dir"), "src/test/assets");
       file = new File(file, dumpFile);
-      file.getParentFile().mkdirs();
+      Assertions.checkStateNotNull(file.getParentFile()).mkdirs();
       PrintWriter out = new PrintWriter(file);
       out.print(actual);
       out.close();

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

@@ -22,7 +22,6 @@ import com.google.android.exoplayer2.source.chunk.MediaChunk;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.upstream.DefaultHttpDataSource;
-import java.io.IOException;
 
 /** Fake {@link MediaChunk}. */
 public final class FakeMediaChunk extends MediaChunk {
@@ -51,7 +50,7 @@ public final class FakeMediaChunk extends MediaChunk {
   }
 
   @Override
-  public void load() throws IOException, InterruptedException {
+  public void load() {
     // Do nothing.
   }
 

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

@@ -35,6 +35,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * Fake {@link MediaPeriod} that provides tracks from the given {@link TrackGroupArray}. Selecting
@@ -149,8 +150,12 @@ public class FakeMediaPeriod implements MediaPeriod {
   }
 
   @Override
-  public long selectTracks(TrackSelection[] selections, boolean[] mayRetainStreamFlags,
+  public long selectTracks(
-      SampleStream[] streams, boolean[] streamResetFlags, long positionUs) {
+      @NullableType TrackSelection[] selections,
+      boolean[] mayRetainStreamFlags,
+      @NullableType SampleStream[] streams,
+      boolean[] streamResetFlags,
+      long positionUs) {
     assertThat(prepared).isTrue();
     sampleStreams.clear();
     int rendererCount = selections.length;

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

@@ -84,7 +84,7 @@ public class FakeRenderer extends BaseRenderer {
       if (result == C.RESULT_FORMAT_READ) {
         formatReadCount++;
         assertThat(expectedFormats).contains(formatHolder.format);
-        onFormatChanged(formatHolder.format);
+        onFormatChanged(Assertions.checkNotNull(formatHolder.format));
       } else if (result == C.RESULT_BUFFER_READ) {
         if (buffer.isEndOfStream()) {
           isEnded = true;

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

@@ -24,9 +24,7 @@ import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 import java.util.Arrays;
 
-/**
+/** Fake {@link Timeline} which can be setup to return custom {@link TimelineWindowDefinition}s. */
- * Fake {@link Timeline} which can be setup to return custom {@link TimelineWindowDefinition}s.
- */
 public final class FakeTimeline extends Timeline {
 
   /**

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

@@ -17,6 +17,7 @@ package com.google.android.exoplayer2.testutil;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
@@ -29,6 +30,8 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /**
  * A fake {@link TrackOutput}.
@@ -39,10 +42,10 @@ public final class FakeTrackOutput implements TrackOutput, Dumper.Dumpable {
   private final ArrayList<Integer> sampleFlags;
   private final ArrayList<Integer> sampleStartOffsets;
   private final ArrayList<Integer> sampleEndOffsets;
-  private final ArrayList<CryptoData> cryptoDatas;
+  private final ArrayList<@NullableType CryptoData> cryptoDatas;
 
   private byte[] sampleData;
-  public Format format;
+  public @MonotonicNonNull Format format;
 
   public FakeTrackOutput() {
     sampleData = Util.EMPTY_BYTE_ARRAY;
@@ -64,6 +67,7 @@ public final class FakeTrackOutput implements TrackOutput, Dumper.Dumpable {
 
   @Override
   public void format(Format format) {
+    // TODO: Capture and assert all formats (interleaved with the samples).
     this.format = format;
   }
 
@@ -91,8 +95,12 @@ public final class FakeTrackOutput implements TrackOutput, Dumper.Dumpable {
   }
 
   @Override
-  public void sampleMetadata(long timeUs, @C.BufferFlags int flags, int size, int offset,
+  public void sampleMetadata(
-      CryptoData cryptoData) {
+      long timeUs,
+      @C.BufferFlags int flags,
+      int size,
+      int offset,
+      @Nullable CryptoData cryptoData) {
     if (format == null) {
       throw new IllegalStateException("TrackOutput must receive format before sampleMetadata");
     }
@@ -110,7 +118,8 @@ public final class FakeTrackOutput implements TrackOutput, Dumper.Dumpable {
     assertThat(sampleTimesUs).hasSize(count);
   }
 
-  public void assertSample(int index, byte[] data, long timeUs, int flags, CryptoData cryptoData) {
+  public void assertSample(
+      int index, byte[] data, long timeUs, int flags, @Nullable CryptoData cryptoData) {
     byte[] actualData = getSampleData(index);
     assertThat(actualData).isEqualTo(data);
     assertThat(sampleTimesUs.get(index)).isEqualTo(timeUs);
@@ -131,6 +140,7 @@ public final class FakeTrackOutput implements TrackOutput, Dumper.Dumpable {
     return sampleFlags.get(index);
   }
 
+  @Nullable
   public CryptoData getSampleCryptoData(int index) {
     return cryptoDatas.get(index);
   }
@@ -162,6 +172,7 @@ public final class FakeTrackOutput implements TrackOutput, Dumper.Dumpable {
 
   @Override
   public void dump(Dumper dumper) {
+    if (format != null) {
       dumper
           .startBlock("format")
           .add("bitrate", format.bitrate)
@@ -190,6 +201,7 @@ public final class FakeTrackOutput implements TrackOutput, Dumper.Dumpable {
         dumper.add("data", format.initializationData.get(i));
       }
       dumper.endBlock().endBlock();
+    }
 
     dumper.add("total output bytes", sampleData.length);
     dumper.add("sample count", sampleTimesUs.size());

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

@@ -17,6 +17,7 @@ package com.google.android.exoplayer2.testutil;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.source.TrackGroup;
@@ -109,6 +110,7 @@ public final class FakeTrackSelection implements TrackSelection {
   }
 
   @Override
+  @Nullable
   public Object getSelectionData() {
     return null;
   }

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

@@ -15,6 +15,8 @@
  */
 package com.google.android.exoplayer2.testutil;
 
+import com.google.android.exoplayer2.RendererCapabilities.AdaptiveSupport;
+import com.google.android.exoplayer2.RendererCapabilities.Capabilities;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
@@ -23,6 +25,7 @@ import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.BandwidthMeter;
 import java.util.ArrayList;
 import java.util.List;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /** A fake {@link MappingTrackSelector} that returns {@link FakeTrackSelection}s. */
 public class FakeTrackSelector extends DefaultTrackSelector {
@@ -30,7 +33,7 @@ public class FakeTrackSelector extends DefaultTrackSelector {
   private final FakeTrackSelectionFactory fakeTrackSelectionFactory;
 
   public FakeTrackSelector() {
-    this(false);
+    this(/* mayReuseTrackSelection= */ false);
   }
 
   /**
@@ -48,13 +51,14 @@ public class FakeTrackSelector extends DefaultTrackSelector {
   }
 
   @Override
-  protected TrackSelection.Definition[] selectAllTracks(
+  protected TrackSelection.@NullableType Definition[] selectAllTracks(
       MappedTrackInfo mappedTrackInfo,
-      int[][][] rendererFormatSupports,
+      @Capabilities int[][][] rendererFormatSupports,
-      int[] rendererMixedMimeTypeAdaptationSupports,
+      @AdaptiveSupport int[] rendererMixedMimeTypeAdaptationSupports,
       Parameters params) {
     int rendererCount = mappedTrackInfo.getRendererCount();
-    TrackSelection.Definition[] definitions = new TrackSelection.Definition[rendererCount];
+    TrackSelection.@NullableType Definition[] definitions =
+        new TrackSelection.Definition[rendererCount];
     for (int i = 0; i < rendererCount; i++) {
       TrackGroupArray trackGroupArray = mappedTrackInfo.getTrackGroups(i);
       boolean hasTracks = trackGroupArray.length > 0;
@@ -80,7 +84,7 @@ public class FakeTrackSelector extends DefaultTrackSelector {
 
     @Override
     public TrackSelection[] createTrackSelections(
-        TrackSelection.Definition[] definitions, BandwidthMeter bandwidthMeter) {
+        @NullableType TrackSelection.Definition[] definitions, BandwidthMeter bandwidthMeter) {
       TrackSelection[] selections = new TrackSelection[definitions.length];
       for (int i = 0; i < definitions.length; i++) {
         TrackSelection.Definition definition = definitions[i];

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

@@ -33,9 +33,7 @@ import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.Util;
 
-/**
+/** A host activity for performing playback tests. */
- * A host activity for performing playback tests.
- */
 public final class HostActivity extends Activity implements SurfaceHolder.Callback {
 
   /**

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

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.testutil;
 
 import android.os.Looper;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.BasePlayer;
 import com.google.android.exoplayer2.ExoPlaybackException;
 import com.google.android.exoplayer2.ExoPlayer;
@@ -250,7 +251,7 @@ public abstract class StubExoPlayer extends BasePlayer implements ExoPlayer {
   }
 
   @Override
-  public void setPlaybackParameters(PlaybackParameters playbackParameters) {
+  public void setPlaybackParameters(@Nullable PlaybackParameters playbackParameters) {
     throw new UnsupportedOperationException();
   }
 
@@ -260,7 +261,7 @@ public abstract class StubExoPlayer extends BasePlayer implements ExoPlayer {
   }
 
   @Override
-  public void setSeekParameters(SeekParameters seekParameters) {
+  public void setSeekParameters(@Nullable SeekParameters seekParameters) {
     throw new UnsupportedOperationException();
   }
 

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

@@ -18,13 +18,16 @@ package com.google.android.exoplayer2.testutil;
 import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.fail;
 
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.offline.Download;
 import com.google.android.exoplayer2.offline.Download.State;
 import com.google.android.exoplayer2.offline.DownloadManager;
+import com.google.android.exoplayer2.util.Util;
 import java.util.HashMap;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /** A {@link DownloadManager.Listener} for testing. */
 public final class TestDownloadManagerListener implements DownloadManager.Listener {
@@ -39,7 +42,7 @@ public final class TestDownloadManagerListener implements DownloadManager.Listen
   private final CountDownLatch initializedCondition;
   private final int timeoutMs;
 
-  private CountDownLatch downloadFinishedCondition;
+  private @MonotonicNonNull CountDownLatch downloadFinishedCondition;
   @Download.FailureReason private int failureReason;
 
   public TestDownloadManagerListener(
@@ -57,6 +60,7 @@ public final class TestDownloadManagerListener implements DownloadManager.Listen
     downloadManager.addListener(this);
   }
 
+  @Nullable
   public Integer pollStateChange(String taskId, long timeoutMs) throws InterruptedException {
     return getStateQueue(taskId).poll(timeoutMs, TimeUnit.MILLISECONDS);
   }
@@ -112,7 +116,7 @@ public final class TestDownloadManagerListener implements DownloadManager.Listen
     dummyMainThread.runOnMainThread(
         () -> {
           if (downloadManager.isIdle()) {
-            downloadFinishedCondition.countDown();
+            Util.castNonNull(downloadFinishedCondition).countDown();
           }
         });
     assertThat(downloadFinishedCondition.await(timeoutMs, TimeUnit.MILLISECONDS)).isTrue();
@@ -120,10 +124,12 @@ public final class TestDownloadManagerListener implements DownloadManager.Listen
 
   private ArrayBlockingQueue<Integer> getStateQueue(String taskId) {
     synchronized (downloadStates) {
-      if (!downloadStates.containsKey(taskId)) {
+      @Nullable ArrayBlockingQueue<Integer> stateQueue = downloadStates.get(taskId);
-        downloadStates.put(taskId, new ArrayBlockingQueue<>(10));
+      if (stateQueue == null) {
+        stateQueue = new ArrayBlockingQueue<>(10);
+        downloadStates.put(taskId, stateQueue);
       }
-      return downloadStates.get(taskId);
+      return stateQueue;
     }
   }
 
@@ -137,11 +143,11 @@ public final class TestDownloadManagerListener implements DownloadManager.Listen
 
   private void assertStateInternal(String taskId, int expectedState, int timeoutMs) {
     while (true) {
-      Integer state = null;
+      @Nullable Integer state = null;
       try {
         state = pollStateChange(taskId, timeoutMs);
       } catch (InterruptedException e) {
-        fail(e.getMessage());
+        fail("Interrupted: " + e.getMessage());
       }
       if (state != null) {
         if (expectedState == state) {

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

@@ -22,6 +22,8 @@ import com.google.android.exoplayer2.Player;
 import com.google.android.exoplayer2.Timeline;
 import com.google.android.exoplayer2.Timeline.Period;
 import com.google.android.exoplayer2.Timeline.Window;
+import com.google.android.exoplayer2.util.Assertions;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /** Unit test for {@link Timeline}. */
 public final class TimelineAsserts {
@@ -48,7 +50,8 @@ public final class TimelineAsserts {
    * @param expectedWindowTags A list of expected window tags. If a tag is unknown or not important
    *     {@code null} can be passed to skip this window.
    */
-  public static void assertWindowTags(Timeline timeline, Object... expectedWindowTags) {
+  public static void assertWindowTags(
+      Timeline timeline, @NullableType Object... expectedWindowTags) {
     Window window = new Window();
     assertThat(timeline.getWindowCount()).isEqualTo(expectedWindowTags.length);
     for (int i = 0; i < timeline.getWindowCount(); i++) {
@@ -140,8 +143,9 @@ public final class TimelineAsserts {
         expectedWindowIndex++;
       }
       assertThat(period.windowIndex).isEqualTo(expectedWindowIndex);
-      assertThat(timeline.getIndexOfPeriod(period.uid)).isEqualTo(i);
+      Object periodUid = Assertions.checkNotNull(period.uid);
-      assertThat(timeline.getUidOfPeriod(i)).isEqualTo(period.uid);
+      assertThat(timeline.getIndexOfPeriod(periodUid)).isEqualTo(i);
+      assertThat(timeline.getUidOfPeriod(i)).isEqualTo(periodUid);
       for (int repeatMode : REPEAT_MODES) {
         if (i < accumulatedPeriodCounts[expectedWindowIndex + 1] - 1) {
           assertThat(timeline.getNextPeriodIndex(i, period, window, repeatMode, false))