More nullness fixes in testutil

PiperOrigin-RevId: 292907271

More nullness fixes in testutil
PiperOrigin-RevId: 292907271
cda6cba5 · olly · Oliver Woodman · ad115a5a · cda6cba5 · cda6cba5
Commit cda6cba5 authored Feb 03, 2020 by olly Committed by Oliver Woodman Feb 03, 2020
Showing with 167 additions and 100 deletions
library/core/src/test/java/com/google/android/exoplayer2/ExoPlayerTest.java
library/core/src/test/java/com/google/android/exoplayer2/MediaPeriodQueueTest.java
library/core/src/test/java/com/google/android/exoplayer2/analytics/AnalyticsCollectorTest.java
library/core/src/test/java/com/google/android/exoplayer2/source/ClippingMediaSourceTest.java
library/core/src/test/java/com/google/android/exoplayer2/source/ConcatenatingMediaSourceTest.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/Action.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/ActionSchedule.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/CacheAsserts.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/ExoHostedTest.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeAdaptiveMediaSource.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeChunkSource.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaPeriod.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaSource.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/HostActivity.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/MediaPeriodAsserts.java
testutils/src/main/java/com/google/android/exoplayer2/testutil/package-info.java
--- a/library/core/src/test/java/com/google/android/exoplayer2/ExoPlayerTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/ExoPlayerTest.java
@@ -484,7 +484,7 @@ public final class ExoPlayerTest {
        new ActionSchedule.Builder("testAdGroupWithLoadErrorIsSkipped")
            .pause()
            .waitForPlaybackState(Player.STATE_READY)
-            .executeRunnable(() -> fakeMediaSource.setNewSourceInfo(adErrorTimeline, null))
+            .executeRunnable(() -> fakeMediaSource.setNewSourceInfo(adErrorTimeline))
            .waitForTimelineChanged(
                adErrorTimeline, /* expectedReason */ Player.TIMELINE_CHANGE_REASON_SOURCE_UPDATE)
            .play()
@@ -864,7 +864,7 @@ public final class ExoPlayerTest {
            .pause()
            .waitForTimelineChanged(
                timeline, /* expectedReason */ Player.TIMELINE_CHANGE_REASON_SOURCE_UPDATE)
-            .executeRunnable(() -> mediaSource.setNewSourceInfo(timeline2, null))
+            .executeRunnable(() -> mediaSource.setNewSourceInfo(timeline2))
            .waitForTimelineChanged(
                timeline2, /* expectedReason */ Player.TIMELINE_CHANGE_REASON_SOURCE_UPDATE)
            .play()
@@ -2061,7 +2061,7 @@ public final class ExoPlayerTest {
            .waitForTimelineChanged(
                timeline, /* expectedReason */ Player.TIMELINE_CHANGE_REASON_SOURCE_UPDATE)
            .sendMessage(target, /* positionMs= */ 50)
-            .executeRunnable(() -> mediaSource.setNewSourceInfo(secondTimeline, null))
+            .executeRunnable(() -> mediaSource.setNewSourceInfo(secondTimeline))
            .waitForTimelineChanged(
                secondTimeline, /* expectedReason */ Player.TIMELINE_CHANGE_REASON_SOURCE_UPDATE)
            .play()
@@ -2137,7 +2137,7 @@ public final class ExoPlayerTest {
            .waitForTimelineChanged(
                timeline, /* expectedReason */ Player.TIMELINE_CHANGE_REASON_SOURCE_UPDATE)
            .sendMessage(target, /* windowIndex = */ 1, /* positionMs= */ 50)
-            .executeRunnable(() -> mediaSource.setNewSourceInfo(secondTimeline, null))
+            .executeRunnable(() -> mediaSource.setNewSourceInfo(secondTimeline))
            .waitForTimelineChanged(
                secondTimeline, /* expectedReason */ Player.TIMELINE_CHANGE_REASON_SOURCE_UPDATE)
            .seek(/* windowIndex= */ 0, /* positionMs= */ 0)
@@ -2223,7 +2223,7 @@ public final class ExoPlayerTest {
  @Test
  public void testCancelRepeatedMessageAfterDelivery() throws Exception {
    Timeline timeline = new FakeTimeline(/* windowCount= */ 1);
-    final PositionGrabbingMessageTarget target = new PositionGrabbingMessageTarget();
+    final CountingMessageTarget target = new CountingMessageTarget();
    final AtomicReference<PlayerMessage> message = new AtomicReference<>();
    ActionSchedule actionSchedule =
        new ActionSchedule.Builder("testCancelMessage")
@@ -2315,7 +2315,7 @@ public final class ExoPlayerTest {
            .playUntilPosition(
                /* windowIndex= */ 0,
                /* positionMs= */ C.usToMs(TimelineWindowDefinition.DEFAULT_WINDOW_DURATION_US))
-            .executeRunnable(() -> mediaSource.setNewSourceInfo(timeline2, /* newManifest= */ null))
+            .executeRunnable(() -> mediaSource.setNewSourceInfo(timeline2))
            .waitForTimelineChanged(
                timeline2, /* expectedReason */ Player.TIMELINE_CHANGE_REASON_SOURCE_UPDATE)
            .play()
@@ -2844,7 +2844,7 @@ public final class ExoPlayerTest {
            .waitForPlaybackState(Player.STATE_BUFFERING)
            .seek(/* positionMs= */ 10)
            .waitForSeekProcessed()
-            .executeRunnable(() -> mediaSource.setNewSourceInfo(timeline, /* newManifest= */ null))
+            .executeRunnable(() -> mediaSource.setNewSourceInfo(timeline))
            .waitForTimelineChanged()
            .waitForPlaybackState(Player.STATE_READY)
            .executeRunnable(
@@ -2889,7 +2889,7 @@ public final class ExoPlayerTest {
            // Seek 10ms into the second period.
            .seek(/* positionMs= */ periodDurationMs + 10)
            .waitForSeekProcessed()
-            .executeRunnable(() -> mediaSource.setNewSourceInfo(timeline, /* newManifest= */ null))
+            .executeRunnable(() -> mediaSource.setNewSourceInfo(timeline))
            .waitForTimelineChanged()
            .waitForPlaybackState(Player.STATE_READY)
            .executeRunnable(
@@ -5682,6 +5682,16 @@ public final class ExoPlayerTest {
  // Internal classes.
+  private static final class CountingMessageTarget implements PlayerMessage.Target {
+    public int messageCount;
+    @Override
+    public void handleMessage(int x, @Nullable Object message) {
+      messageCount++;
+    }
+  }
  private static final class PositionGrabbingMessageTarget extends PlayerTarget {
    public int windowIndex;
@@ -5695,10 +5705,8 @@ public final class ExoPlayerTest {
    @Override
    public void handleMessage(SimpleExoPlayer player, int messageType, @Nullable Object message) {
-      if (player != null) {
+      windowIndex = player.getCurrentWindowIndex();
-        windowIndex = player.getCurrentWindowIndex();
+      positionMs = player.getCurrentPosition();
-        positionMs = player.getCurrentPosition();
-      }
      messageCount++;
    }
  }

--- a/library/core/src/test/java/com/google/android/exoplayer2/MediaPeriodQueueTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/MediaPeriodQueueTest.java
@@ -374,7 +374,7 @@ public final class MediaPeriodQueueTest {
  private void updateTimeline() {
    SinglePeriodAdTimeline adTimeline =
        new SinglePeriodAdTimeline(CONTENT_TIMELINE, adPlaybackState);
-    fakeMediaSource.setNewSourceInfo(adTimeline, /* manifest */ null);
+    fakeMediaSource.setNewSourceInfo(adTimeline);
    playbackInfo = playbackInfo.copyWithTimeline(createPlaylistTimeline());
  }

--- a/library/core/src/test/java/com/google/android/exoplayer2/analytics/AnalyticsCollectorTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/analytics/AnalyticsCollectorTest.java
@@ -785,8 +785,7 @@ public final class AnalyticsCollectorTest {
                                          /* isSeekable= */ true,
                                          /* isDynamic= */ false,
                                          /* durationUs =*/ 10 * C.MICROS_PER_SECOND,
-                                          adPlaybackState.get())),
+                                          adPlaybackState.get())));
-                                  /* newManifest= */ null);
                            }
                          }
                        });

--- a/library/core/src/test/java/com/google/android/exoplayer2/source/ClippingMediaSourceTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/source/ClippingMediaSourceTest.java
@@ -635,7 +635,7 @@ public final class ClippingMediaSourceTest {
                  clippedTimelines[0].getUidOfPeriod(/* periodIndex= */ 0),
                  /* windowSequenceNumber= */ 0));
      for (int i = 0; i < additionalTimelines.length; i++) {
-        fakeMediaSource.setNewSourceInfo(additionalTimelines[i], /* newManifest= */ null);
+        fakeMediaSource.setNewSourceInfo(additionalTimelines[i]);
        clippedTimelines[i + 1] = testRunner.assertTimelineChangeBlocking();
      }
      testRunner.releasePeriod(mediaPeriod);

--- a/library/core/src/test/java/com/google/android/exoplayer2/source/ConcatenatingMediaSourceTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/source/ConcatenatingMediaSourceTest.java
@@ -246,8 +246,7 @@ public final class ConcatenatingMediaSourceTest {
    // Trigger source info refresh for lazy source and check that the timeline now contains all
    // information for all windows.
-    testRunner.runOnPlaybackThread(
+    testRunner.runOnPlaybackThread(() -> lazySources[1].setNewSourceInfo(createFakeTimeline(8)));
-        () -> lazySources[1].setNewSourceInfo(createFakeTimeline(8), null));
    timeline = testRunner.assertTimelineChangeBlocking();
    TimelineAsserts.assertPeriodCounts(timeline, 1, 9);
    TimelineAsserts.assertWindowTags(timeline, 111, 999);
@@ -281,8 +280,7 @@ public final class ConcatenatingMediaSourceTest {
    // Trigger source info refresh for lazy media source. Assert that now all information is
    // available again and the previously created period now also finished preparing.
-    testRunner.runOnPlaybackThread(
+    testRunner.runOnPlaybackThread(() -> lazySources[3].setNewSourceInfo(createFakeTimeline(7)));
-        () -> lazySources[3].setNewSourceInfo(createFakeTimeline(7), null));
    timeline = testRunner.assertTimelineChangeBlocking();
    TimelineAsserts.assertPeriodCounts(timeline, 8, 1, 2, 9);
    TimelineAsserts.assertWindowTags(timeline, 888, 111, 222, 999);
@@ -372,15 +370,15 @@ public final class ConcatenatingMediaSourceTest {
    Timeline timeline = testRunner.prepareSource();
    TimelineAsserts.assertEmpty(timeline);
-    childSources[0].setNewSourceInfo(nonEmptyTimeline, /* newManifest== */ null);
+    childSources[0].setNewSourceInfo(nonEmptyTimeline);
    timeline = testRunner.assertTimelineChangeBlocking();
    TimelineAsserts.assertPeriodCounts(timeline, 1);
-    childSources[2].setNewSourceInfo(nonEmptyTimeline, /* newManifest== */ null);
+    childSources[2].setNewSourceInfo(nonEmptyTimeline);
    timeline = testRunner.assertTimelineChangeBlocking();
    TimelineAsserts.assertPeriodCounts(timeline, 1, 1);
-    childSources[1].setNewSourceInfo(nonEmptyTimeline, /* newManifest== */ null);
+    childSources[1].setNewSourceInfo(nonEmptyTimeline);
    timeline = testRunner.assertTimelineChangeBlocking();
    TimelineAsserts.assertPeriodCounts(timeline, 1, 1, 1);
  }

--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/Action.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/Action.java
--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/ActionSchedule.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/ActionSchedule.java
@@ -54,6 +54,7 @@ import com.google.android.exoplayer2.testutil.Action.WaitForTimelineChanged;
 import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.HandlerWrapper;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 /**
 * Schedules a sequence of {@link Action}s for execution during a test.
@@ -89,7 +90,8 @@ public final class ActionSchedule {
   *
   * @param player The player to which actions should be applied.
   * @param trackSelector The track selector to which actions should be applied.
-   * @param surface The surface to use when applying actions.
+   * @param surface The surface to use when applying actions, or {@code null} if no surface is
+   *     needed.
   * @param mainHandler A handler associated with the main thread of the host activity.
   * @param callback A {@link Callback} to notify when the action schedule finishes, or null if no
   *     notification is needed.
@@ -97,7 +99,7 @@ public final class ActionSchedule {
  /* package */ void start(
      SimpleExoPlayer player,
      DefaultTrackSelector trackSelector,
-      Surface surface,
+      @Nullable Surface surface,
      HandlerWrapper mainHandler,
      @Nullable Callback callback) {
    callbackAction.setCallback(callback);
@@ -607,9 +609,9 @@ public final class ActionSchedule {
      void onMessageArrived();
    }
-    private SimpleExoPlayer player;
+    @Nullable private SimpleExoPlayer player;
    private boolean hasArrived;
-    private Callback callback;
+    @Nullable private Callback callback;
    public void setCallback(Callback callback) {
      this.callback = callback;
@@ -629,7 +631,7 @@ public final class ActionSchedule {
    @Override
    public final void handleMessage(int messageType, @Nullable Object message) {
-      handleMessage(player, messageType, message);
+      handleMessage(Assertions.checkStateNotNull(player), messageType, message);
      if (callback != null) {
        hasArrived = true;
        callback.onMessageArrived();
@@ -643,7 +645,7 @@ public final class ActionSchedule {
   */
  public abstract static class PlayerRunnable implements Runnable {
-    private SimpleExoPlayer player;
+    @Nullable private SimpleExoPlayer player;
    /** Executes Runnable with reference to player. */
    public abstract void run(SimpleExoPlayer player);
@@ -655,7 +657,7 @@ public final class ActionSchedule {
    @Override
    public final void run() {
-      run(player);
+      run(Assertions.checkStateNotNull(player));
    }
  }
@@ -666,12 +668,12 @@ public final class ActionSchedule {
    private final long delayMs;
    private final long repeatIntervalMs;
-    private ActionNode next;
+    @Nullable private ActionNode next;
-    private SimpleExoPlayer player;
+    private @MonotonicNonNull SimpleExoPlayer player;
-    private DefaultTrackSelector trackSelector;
+    private @MonotonicNonNull DefaultTrackSelector trackSelector;
-    private Surface surface;
+    @Nullable private Surface surface;
-    private HandlerWrapper mainHandler;
+    private @MonotonicNonNull HandlerWrapper mainHandler;
    /**
     * @param action The wrapped action.
@@ -708,13 +710,13 @@ public final class ActionSchedule {
     *
     * @param player The player to which actions should be applied.
     * @param trackSelector The track selector to which actions should be applied.
-     * @param surface The surface to use when applying actions.
+     * @param surface The surface to use when applying actions, or {@code null}.
     * @param mainHandler A handler associated with the main thread of the host activity.
     */
    public void schedule(
        SimpleExoPlayer player,
        DefaultTrackSelector trackSelector,
-        Surface surface,
+        @Nullable Surface surface,
        HandlerWrapper mainHandler) {
      this.player = player;
      this.trackSelector = trackSelector;
@@ -729,14 +731,20 @@ public final class ActionSchedule {
    @Override
    public void run() {
-      action.doActionAndScheduleNext(player, trackSelector, surface, mainHandler, next);
+      action.doActionAndScheduleNext(
+          Assertions.checkStateNotNull(player),
+          Assertions.checkStateNotNull(trackSelector),
+          surface,
+          Assertions.checkStateNotNull(mainHandler),
+          next);
      if (repeatIntervalMs != C.TIME_UNSET) {
        mainHandler.postDelayed(
            new Runnable() {
              @Override
              public void run() {
-                action.doActionAndScheduleNext(player, trackSelector, surface, mainHandler, null);
+                action.doActionAndScheduleNext(
-                mainHandler.postDelayed(this, repeatIntervalMs);
+                    player, trackSelector, surface, mainHandler, /* nextAction= */ null);
+                mainHandler.postDelayed(/* runnable= */ this, repeatIntervalMs);
              }
            },
            repeatIntervalMs);
@@ -756,7 +764,7 @@ public final class ActionSchedule {
    @Override
    protected void doActionImpl(
-        SimpleExoPlayer player, DefaultTrackSelector trackSelector, Surface surface) {
+        SimpleExoPlayer player, DefaultTrackSelector trackSelector, @Nullable Surface surface) {
      // Do nothing.
    }
  }
@@ -780,18 +788,19 @@ public final class ActionSchedule {
    protected void doActionAndScheduleNextImpl(
        SimpleExoPlayer player,
        DefaultTrackSelector trackSelector,
-        Surface surface,
+        @Nullable Surface surface,
        HandlerWrapper handler,
-        ActionNode nextAction) {
+        @Nullable ActionNode nextAction) {
      Assertions.checkArgument(nextAction == null);
+      @Nullable Callback callback = this.callback;
      if (callback != null) {
-        handler.post(() -> callback.onActionScheduleFinished());
+        handler.post(callback::onActionScheduleFinished);
      }
    }
    @Override
    protected void doActionImpl(
-        SimpleExoPlayer player, DefaultTrackSelector trackSelector, Surface surface) {
+        SimpleExoPlayer player, DefaultTrackSelector trackSelector, @Nullable Surface surface) {
      // Not triggered.
    }
  }

--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/CacheAsserts.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/CacheAsserts.java
@@ -26,6 +26,7 @@ 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.CacheDataSource;
+import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
 import java.util.ArrayList;
@@ -44,7 +45,7 @@ public final class CacheAsserts {
      ArrayList<FakeData> allData = fakeDataSet.getAllData();
      dataSpecs = new DataSpec[allData.size()];
      for (int i = 0; i < dataSpecs.length; i++) {
-        dataSpecs[i] = new DataSpec(allData.get(i).uri);
+        dataSpecs[i] = new DataSpec(Assertions.checkNotNull(allData.get(i).uri));
      }
    }
@@ -74,7 +75,7 @@ public final class CacheAsserts {
    }
    public byte[] getData(int i) {
-      return fakeDataSet.getData(dataSpecs[i].uri).getData();
+      return Assertions.checkNotNull(fakeDataSet.getData(dataSpecs[i].uri)).getData();
    }
    public DataSpec getDataSpec(int i) {
@@ -82,10 +83,10 @@ public final class CacheAsserts {
    }
    public RequestSet useBoundedDataSpecFor(String uriString) {
-      FakeData data = fakeDataSet.getData(uriString);
+      FakeData data = Assertions.checkStateNotNull(fakeDataSet.getData(uriString));
      for (int i = 0; i < dataSpecs.length; i++) {
        DataSpec spec = dataSpecs[i];
-        if (spec.uri.getPath().equals(uriString)) {
+        if (Assertions.checkNotNull(spec.uri.getPath()).equals(uriString)) {
          dataSpecs[i] = spec.subrange(0, data.getData().length);
          return this;
        }
@@ -148,13 +149,10 @@ public final class CacheAsserts {
   */
  public static void assertReadData(DataSource dataSource, DataSpec dataSpec, byte[] expected)
      throws IOException {
-    byte[] bytes = null;
    try (DataSourceInputStream inputStream = new DataSourceInputStream(dataSource, dataSpec)) {
-      bytes = Util.toByteArray(inputStream);
+      byte[] bytes = Util.toByteArray(inputStream);
-    } catch (IOException e) {
+      assertThat(bytes).isEqualTo(expected);
-      // Ignore
    }
-    assertThat(bytes).isEqualTo(expected);
  }
  /** Asserts that the cache is empty. */

--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/ExoHostedTest.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/ExoHostedTest.java
@@ -18,9 +18,9 @@ package com.google.android.exoplayer2.testutil;
 import static com.google.common.truth.Truth.assertWithMessage;
 import android.os.ConditionVariable;
-import android.os.Looper;
 import android.os.SystemClock;
 import android.view.Surface;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.DefaultRenderersFactory;
 import com.google.android.exoplayer2.ExoPlaybackException;
@@ -41,6 +41,8 @@ import com.google.android.exoplayer2.util.EventLogger;
 import com.google.android.exoplayer2.util.HandlerWrapper;
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.Util;
+import org.checkerframework.checker.nullness.qual.EnsuresNonNullIf;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 /** A {@link HostedTest} for {@link ExoPlayer} playback tests. */
 public abstract class ExoHostedTest implements AnalyticsListener, HostedTest {
@@ -64,12 +66,12 @@ public abstract class ExoHostedTest implements AnalyticsListener, HostedTest {
  private final DecoderCounters audioDecoderCounters;
  private final ConditionVariable testFinished;
-  private ActionSchedule pendingSchedule;
+  @Nullable private ActionSchedule pendingSchedule;
-  private HandlerWrapper actionHandler;
+  private @MonotonicNonNull SimpleExoPlayer player;
-  private DefaultTrackSelector trackSelector;
+  private @MonotonicNonNull HandlerWrapper actionHandler;
-  private SimpleExoPlayer player;
+  private @MonotonicNonNull DefaultTrackSelector trackSelector;
-  private Surface surface;
+  private @MonotonicNonNull Surface surface;
-  private ExoPlaybackException playerError;
+  private @MonotonicNonNull ExoPlaybackException playerError;
  private boolean playerWasPrepared;
  private boolean playing;
@@ -115,7 +117,7 @@ public abstract class ExoHostedTest implements AnalyticsListener, HostedTest {
   * @param schedule The schedule.
   */
  public final void setSchedule(ActionSchedule schedule) {
-    if (player == null) {
+    if (!isStarted()) {
      pendingSchedule = schedule;
    } else {
      schedule.start(player, trackSelector, surface, actionHandler, /* callback= */ null);
@@ -135,7 +137,7 @@ public abstract class ExoHostedTest implements AnalyticsListener, HostedTest {
    player.addAnalyticsListener(this);
    player.addAnalyticsListener(new EventLogger(trackSelector, tag));
    // Schedule any pending actions.
-    actionHandler = Clock.DEFAULT.createHandler(Looper.myLooper(), /* callback= */ null);
+    actionHandler = Clock.DEFAULT.createHandler(Util.getLooper(), /* callback= */ null);
    if (pendingSchedule != null) {
      pendingSchedule.start(player, trackSelector, surface, actionHandler, /* callback= */ null);
      pendingSchedule = null;
@@ -216,13 +218,12 @@ public abstract class ExoHostedTest implements AnalyticsListener, HostedTest {
  // Internal logic
  private boolean stopTest() {
-    if (player == null) {
+    if (!isStarted()) {
      return false;
    }
    actionHandler.removeCallbacksAndMessages(null);
    sourceDurationMs = player.getDuration();
    player.release();
-    player = null;
    // We post opening of the finished condition so that any events posted to the main thread as a
    // result of player.release() are guaranteed to be handled before the test returns.
    actionHandler.post(testFinished::open);
@@ -261,4 +262,17 @@ public abstract class ExoHostedTest implements AnalyticsListener, HostedTest {
  protected void onTestFinished(DecoderCounters audioCounters, DecoderCounters videoCounters) {
    // Do nothing. Subclasses may override to add clean-up and assertions.
  }
+  @EnsuresNonNullIf(
+      result = true,
+      expression = {"player", "actionHandler", "trackSelector", "surface"})
+  private boolean isStarted() {
+    if (player == null) {
+      return false;
+    }
+    Util.castNonNull(actionHandler);
+    Util.castNonNull(trackSelector);
+    Util.castNonNull(surface);
+    return true;
+  }
 }
--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeAdaptiveMediaSource.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeAdaptiveMediaSource.java
@@ -23,6 +23,7 @@ import com.google.android.exoplayer2.source.MediaSourceEventListener.EventDispat
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.upstream.Allocator;
 import com.google.android.exoplayer2.upstream.TransferListener;
+import com.google.android.exoplayer2.util.Util;
 /**
 * Fake {@link MediaSource} that provides a given timeline. Creating the period returns a
@@ -47,7 +48,7 @@ public class FakeAdaptiveMediaSource extends FakeMediaSource {
      Allocator allocator,
      EventDispatcher eventDispatcher,
      @Nullable TransferListener transferListener) {
-    Period period = timeline.getPeriodByUid(id.periodUid, new Period());
+    Period period = Util.castNonNull(getTimeline()).getPeriodByUid(id.periodUid, new Period());
    return new FakeAdaptiveMediaPeriod(
        trackGroupArray,
        eventDispatcher,

--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeChunkSource.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeChunkSource.java
@@ -31,8 +31,8 @@ import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.upstream.TransferListener;
+import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.MimeTypes;
-import java.io.IOException;
 import java.util.List;
 /**
@@ -93,7 +93,7 @@ public final class FakeChunkSource implements ChunkSource {
  }
  @Override
-  public void maybeThrowError() throws IOException {
+  public void maybeThrowError() {
    // Do nothing.
  }
@@ -128,7 +128,8 @@ public final class FakeChunkSource implements ChunkSource {
      long endTimeUs = startTimeUs + dataSet.getChunkDuration(chunkIndex);
      int trackGroupIndex = trackSelection.getIndexInTrackGroup(trackSelection.getSelectedIndex());
      String uri = dataSet.getUri(trackGroupIndex);
-      Segment fakeDataChunk = dataSet.getData(uri).getSegments().get(chunkIndex);
+      Segment fakeDataChunk =
+          Assertions.checkStateNotNull(dataSet.getData(uri)).getSegments().get(chunkIndex);
      DataSpec dataSpec = new DataSpec(Uri.parse(uri), fakeDataChunk.byteOffset,
          fakeDataChunk.length, null);
      int trackType = MimeTypes.getTrackType(selectedFormat.sampleMimeType);

--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaPeriod.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaPeriod.java
@@ -272,7 +272,7 @@ public class FakeMediaPeriod implements MediaPeriod {
  private void finishPreparation() {
    prepared = true;
-    prepareCallback.onPrepared(this);
+    Util.castNonNull(prepareCallback).onPrepared(this);
    eventDispatcher.loadCompleted(
        FAKE_DATA_SPEC,
        FAKE_DATA_SPEC.uri,

--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaSource.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaSource.java
@@ -43,6 +43,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 /**
 * Fake {@link MediaSource} that provides a given timeline. Creating the period will return a {@link
@@ -73,17 +74,17 @@ public class FakeMediaSource extends BaseMediaSource {
  private final ArrayList<FakeMediaPeriod> activeMediaPeriods;
  private final ArrayList<MediaPeriodId> createdMediaPeriods;
-  protected Timeline timeline;
+  private @MonotonicNonNull Timeline timeline;
  private boolean preparedSource;
  private boolean releasedSource;
-  private Handler sourceInfoRefreshHandler;
+  @Nullable private Handler sourceInfoRefreshHandler;
  @Nullable private TransferListener transferListener;
  /**
   * Creates a {@link FakeMediaSource}. This media source creates {@link FakeMediaPeriod}s with a
   * {@link TrackGroupArray} using the given {@link Format}s. The provided {@link Timeline} may be
   * null to prevent an immediate source info refresh message when preparing the media source. It
-   * can be manually set later using {@link #setNewSourceInfo(Timeline, Object)}.
+   * can be manually set later using {@link #setNewSourceInfo(Timeline)}.
   */
  public FakeMediaSource(@Nullable Timeline timeline, Format... formats) {
    this(timeline, buildTrackGroupArray(formats));
@@ -93,20 +94,29 @@ public class FakeMediaSource extends BaseMediaSource {
   * Creates a {@link FakeMediaSource}. This media source creates {@link FakeMediaPeriod}s with the
   * given {@link TrackGroupArray}. The provided {@link Timeline} may be null to prevent an
   * immediate source info refresh message when preparing the media source. It can be manually set
-   * later using {@link #setNewSourceInfo(Timeline, Object)}.
+   * later using {@link #setNewSourceInfo(Timeline)}.
   */
  public FakeMediaSource(@Nullable Timeline timeline, TrackGroupArray trackGroupArray) {
-    this.timeline = timeline;
+    if (timeline != null) {
+      this.timeline = timeline;
+    }
+    this.trackGroupArray = trackGroupArray;
    this.activeMediaPeriods = new ArrayList<>();
    this.createdMediaPeriods = new ArrayList<>();
-    this.trackGroupArray = trackGroupArray;
+  }
+  @Nullable
+  protected Timeline getTimeline() {
+    return timeline;
  }
  @Override
  @Nullable
  public Object getTag() {
-    boolean hasTimeline = timeline != null && !timeline.isEmpty();
+    if (timeline == null || timeline.isEmpty()) {
-    return hasTimeline ? timeline.getWindow(0, new Timeline.Window()).tag : null;
+      return null;
+    }
+    return timeline.getWindow(0, new Timeline.Window()).tag;
  }
  @Nullable
@@ -143,7 +153,7 @@ public class FakeMediaSource extends BaseMediaSource {
  public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator, long startPositionUs) {
    assertThat(preparedSource).isTrue();
    assertThat(releasedSource).isFalse();
-    int periodIndex = timeline.getIndexOfPeriod(id.periodUid);
+    int periodIndex = Util.castNonNull(timeline).getIndexOfPeriod(id.periodUid);
    Assertions.checkArgument(periodIndex != C.INDEX_UNSET);
    Period period = timeline.getPeriod(periodIndex, new Period());
    EventDispatcher eventDispatcher =
@@ -171,15 +181,15 @@ public class FakeMediaSource extends BaseMediaSource {
    assertThat(activeMediaPeriods.isEmpty()).isTrue();
    releasedSource = true;
    preparedSource = false;
-    sourceInfoRefreshHandler.removeCallbacksAndMessages(null);
+    Util.castNonNull(sourceInfoRefreshHandler).removeCallbacksAndMessages(null);
    sourceInfoRefreshHandler = null;
  }
  /**
-   * Sets a new timeline and manifest. If the source is already prepared, this triggers a source
+   * Sets a new timeline. If the source is already prepared, this triggers a source info refresh
-   * info refresh message being sent to the listener.
+   * message being sent to the listener.
   */
-  public synchronized void setNewSourceInfo(final Timeline newTimeline, final Object newManifest) {
+  public synchronized void setNewSourceInfo(final Timeline newTimeline) {
    if (sourceInfoRefreshHandler != null) {
      sourceInfoRefreshHandler.post(
          () -> {
@@ -238,7 +248,7 @@ public class FakeMediaSource extends BaseMediaSource {
  }
  private void finishSourcePreparation() {
-    refreshSourceInfo(timeline);
+    refreshSourceInfo(Assertions.checkStateNotNull(timeline));
    if (!timeline.isEmpty()) {
      MediaLoadData mediaLoadData =
          new MediaLoadData(

--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/HostActivity.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/HostActivity.java
@@ -29,9 +29,11 @@ import android.view.Surface;
 import android.view.SurfaceHolder;
 import android.view.SurfaceView;
 import android.view.Window;
+import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.Util;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 /** A host activity for performing playback tests. */
 public final class HostActivity extends Activity implements SurfaceHolder.Callback {
@@ -81,13 +83,13 @@ public final class HostActivity extends Activity implements SurfaceHolder.Callba
  private static final String LOCK_TAG = "ExoPlayerTestUtil:" + TAG;
  private static final long START_TIMEOUT_MS = 5000;
-  private WakeLock wakeLock;
+  @Nullable private WakeLock wakeLock;
-  private WifiLock wifiLock;
+  @Nullable private WifiLock wifiLock;
-  private SurfaceView surfaceView;
+  private @MonotonicNonNull SurfaceView surfaceView;
-  private HostedTest hostedTest;
+  @Nullable private HostedTest hostedTest;
  private boolean hostedTestStarted;
-  private ConditionVariable hostedTestStartedCondition;
+  private @MonotonicNonNull ConditionVariable hostedTestStartedCondition;
  private boolean forcedStopped;
  /**
@@ -161,7 +163,7 @@ public final class HostActivity extends Activity implements SurfaceHolder.Callba
  // Activity lifecycle
  @Override
-  public void onCreate(Bundle savedInstanceState) {
+  public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(
@@ -174,10 +176,14 @@ public final class HostActivity extends Activity implements SurfaceHolder.Callba
  @Override
  public void onStart() {
    Context appContext = getApplicationContext();
-    WifiManager wifiManager = (WifiManager) appContext.getSystemService(Context.WIFI_SERVICE);
+    WifiManager wifiManager =
+        Assertions.checkStateNotNull(
+            (WifiManager) appContext.getSystemService(Context.WIFI_SERVICE));
    wifiLock = wifiManager.createWifiLock(WifiManager.WIFI_MODE_FULL_HIGH_PERF, LOCK_TAG);
    wifiLock.acquire();
-    PowerManager powerManager = (PowerManager) appContext.getSystemService(Context.POWER_SERVICE);
+    PowerManager powerManager =
+        Assertions.checkStateNotNull(
+            (PowerManager) appContext.getSystemService(Context.POWER_SERVICE));
    wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, LOCK_TAG);
    wakeLock.acquire();
    super.onStart();
@@ -197,10 +203,14 @@ public final class HostActivity extends Activity implements SurfaceHolder.Callba
    if (Util.SDK_INT > 23) {
      maybeStopHostedTest();
    }
-    wakeLock.release();
+    if (wakeLock != null) {
-    wakeLock = null;
+      wakeLock.release();
-    wifiLock.release();
+      wakeLock = null;
-    wifiLock = null;
+    }
+    if (wifiLock != null) {
+      wifiLock.release();
+      wifiLock = null;
+    }
  }
  // SurfaceHolder.Callback
@@ -226,12 +236,12 @@ public final class HostActivity extends Activity implements SurfaceHolder.Callba
    if (hostedTest == null || hostedTestStarted) {
      return;
    }
-    Surface surface = surfaceView.getHolder().getSurface();
+    @Nullable Surface surface = Util.castNonNull(surfaceView).getHolder().getSurface();
    if (surface != null && surface.isValid()) {
      hostedTestStarted = true;
      Log.d(TAG, "Starting test.");
-      hostedTest.onStart(this, surface);
+      Util.castNonNull(hostedTest).onStart(this, surface);
-      hostedTestStartedCondition.open();
+      Util.castNonNull(hostedTestStartedCondition).open();
    }
  }

--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/MediaPeriodAsserts.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/MediaPeriodAsserts.java
@@ -187,7 +187,7 @@ public final class MediaPeriodAsserts {
  }
  private static TrackGroupArray getTrackGroups(MediaPeriod mediaPeriod) {
-    AtomicReference<TrackGroupArray> trackGroupArray = new AtomicReference<>(null);
+    AtomicReference<TrackGroupArray> trackGroupArray = new AtomicReference<>();
    DummyMainThread dummyMainThread = new DummyMainThread();
    ConditionVariable preparedCondition = new ConditionVariable();
    dummyMainThread.runOnMainThread(

--- a/testutils/src/main/java/com/google/android/exoplayer2/testutil/package-info.java
+++ b/testutils/src/main/java/com/google/android/exoplayer2/testutil/package-info.java
+/*
+ * Copyright (C) 2019 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.
+ */
+@NonNullApi
+package com.google.android.exoplayer2.testutil;
+import com.google.android.exoplayer2.util.NonNullApi;