diff --git a/extensions/cast/src/test/java/com/google/android/exoplayer2/ext/cast/CastPlayerTest.java b/extensions/cast/src/test/java/com/google/android/exoplayer2/ext/cast/CastPlayerTest.java
new file mode 100644
index 0000000000..b2aa0b7b16
--- /dev/null
+++ b/extensions/cast/src/test/java/com/google/android/exoplayer2/ext/cast/CastPlayerTest.java
@@ -0,0 +1,122 @@
+/*
+ * 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.
+ */
+package com.google.android.exoplayer2.ext.cast;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+import static org.mockito.MockitoAnnotations.initMocks;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import com.google.android.exoplayer2.Player;
+import com.google.android.gms.cast.framework.CastContext;
+import com.google.android.gms.cast.framework.CastSession;
+import com.google.android.gms.cast.framework.SessionManager;
+import com.google.android.gms.cast.framework.media.RemoteMediaClient;
+import com.google.android.gms.common.api.PendingResult;
+import com.google.android.gms.common.api.ResultCallback;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+
+/** Tests for {@link CastPlayer}. */
+@RunWith(AndroidJUnit4.class)
+public class CastPlayerTest {
+
+  private CastPlayer castPlayer;
+  private RemoteMediaClient.Listener remoteMediaClientListener;
+  @Mock private RemoteMediaClient mockRemoteMediaClient;
+  @Mock private CastContext mockCastContext;
+  @Mock private SessionManager mockSessionManager;
+  @Mock private CastSession mockCastSession;
+  @Mock private Player.EventListener mockListener;
+  @Mock private PendingResult<RemoteMediaClient.MediaChannelResult> mockPendingResult;
+
+  @Captor
+  private ArgumentCaptor<ResultCallback<RemoteMediaClient.MediaChannelResult>>
+      setResultCallbackArgumentCaptor;
+
+  @Captor private ArgumentCaptor<RemoteMediaClient.Listener> listenerArgumentCaptor;
+
+  @Before
+  public void setUp() {
+    initMocks(this);
+    when(mockCastContext.getSessionManager()).thenReturn(mockSessionManager);
+    when(mockSessionManager.getCurrentCastSession()).thenReturn(mockCastSession);
+    when(mockCastSession.getRemoteMediaClient()).thenReturn(mockRemoteMediaClient);
+    // Make the remote media client be initially paused (most common scenario).
+    when(mockRemoteMediaClient.isPaused()).thenReturn(true);
+    castPlayer = new CastPlayer(mockCastContext);
+    castPlayer.addListener(mockListener);
+    verify(mockRemoteMediaClient).addListener(listenerArgumentCaptor.capture());
+    remoteMediaClientListener = listenerArgumentCaptor.getValue();
+  }
+
+  @Test
+  public void testSetPlayWhenReady_masksLocalState() {
+    when(mockRemoteMediaClient.play()).thenReturn(mockPendingResult);
+    // Initially paused.
+    assertThat(castPlayer.getPlayWhenReady()).isFalse();
+
+    castPlayer.setPlayWhenReady(true);
+    verify(mockPendingResult).setResultCallback(setResultCallbackArgumentCaptor.capture());
+    assertThat(castPlayer.getPlayWhenReady()).isTrue();
+    verify(mockListener).onPlayerStateChanged(true, Player.STATE_IDLE);
+
+    // There is a status update in the middle, which should be hidden by masking.
+    remoteMediaClientListener.onStatusUpdated();
+    Mockito.verifyNoMoreInteractions(mockListener);
+
+    // Upon result, the remoteMediaClient has updated it's state according to the play() call.
+    when(mockRemoteMediaClient.isPaused()).thenReturn(false);
+    setResultCallbackArgumentCaptor
+        .getValue()
+        .onResult(Mockito.mock(RemoteMediaClient.MediaChannelResult.class));
+    Mockito.verifyNoMoreInteractions(mockListener);
+  }
+
+  @Test
+  public void testSetPlayWhenReadyMasking_updatesUponResultChange() {
+    when(mockRemoteMediaClient.play()).thenReturn(mockPendingResult);
+    // Initially paused.
+    assertThat(castPlayer.getPlayWhenReady()).isFalse();
+
+    castPlayer.setPlayWhenReady(true);
+    verify(mockPendingResult).setResultCallback(setResultCallbackArgumentCaptor.capture());
+    assertThat(castPlayer.getPlayWhenReady()).isTrue();
+    verify(mockListener).onPlayerStateChanged(true, Player.STATE_IDLE);
+
+    // Upon result, the remote media client is still paused. So the state should update.
+    setResultCallbackArgumentCaptor
+        .getValue()
+        .onResult(Mockito.mock(RemoteMediaClient.MediaChannelResult.class));
+    verify(mockListener).onPlayerStateChanged(false, Player.STATE_IDLE);
+    assertThat(castPlayer.getPlayWhenReady()).isFalse();
+  }
+
+  @Test
+  public void testPlayWhenReady_changesOnStatusUpdates() {
+    assertThat(castPlayer.getPlayWhenReady()).isFalse();
+    when(mockRemoteMediaClient.isPaused()).thenReturn(false);
+    remoteMediaClientListener.onStatusUpdated();
+    verify(mockListener).onPlayerStateChanged(true, Player.STATE_IDLE);
+    assertThat(castPlayer.getPlayWhenReady()).isTrue();
+  }
+}