Add clearkey-based DRM playback emulator tests

These give some documentation-as-code for a clearkey integration with
ExoPlayer.

#exofixit

PiperOrigin-RevId: 398017708

library/core/build.gradle

@@ -48,6 +48,7 @@ dependencies {
     androidTestImplementation(project(modulePrefix + 'testutils')) {
         exclude module: modulePrefix.substring(1) + 'library-core'
     }
+    androidTestImplementation 'com.squareup.okhttp3:mockwebserver:' + okhttpVersion
     testImplementation 'com.squareup.okhttp3:mockwebserver:' + okhttpVersion
     testImplementation 'org.robolectric:robolectric:' + robolectricVersion
     testImplementation project(modulePrefix + 'testutils')

library/core/src/androidTest/AndroidManifest.xml

@@ -19,11 +19,13 @@
     package="com.google.android.exoplayer2.core.test">
 
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
+  <uses-permission android:name="android.permission.INTERNET"/>
   <uses-sdk/>
 
   <application
       android:allowBackup="false"
-      tools:ignore="MissingApplicationIcon,HardcodedDebugMode">
+      tools:ignore="MissingApplicationIcon,HardcodedDebugMode"
+      android:usesCleartextTraffic="true">
     <provider
       android:authorities="com.google.android.exoplayer2.core.test"
       android:name="com.google.android.exoplayer2.upstream.TestContentProvider"/>

library/core/src/androidTest/java/com/google/android/exoplayer2/drm/DrmPlaybackTest.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2021 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.drm;
+
+import static androidx.test.platform.app.InstrumentationRegistry.getInstrumentation;
+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.ExoPlayer;
+import com.google.android.exoplayer2.MediaItem;
+import com.google.android.exoplayer2.PlaybackException;
+import com.google.android.exoplayer2.Player;
+import com.google.android.exoplayer2.SimpleExoPlayer;
+import com.google.android.exoplayer2.util.ConditionVariable;
+import java.util.concurrent.atomic.AtomicReference;
+import okhttp3.mockwebserver.MockResponse;
+import okhttp3.mockwebserver.MockWebServer;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/** Instrumentation tests for DRM playback. */
+@RunWith(AndroidJUnit4.class)
+public final class DrmPlaybackTest {
+
+  /** The license response needed to play the {@code drm/sample_fragmented_clearkey.mp4} file. */
+  // NOTE: Changing this response *should* make the test fail, but it seems the clearkey CDM
+  // implementation is quite robust. This means an 'invalid' response means it just incorrectly
+  // decrypts the content, resulting in invalid data fed to the decoder and no video shown on the
+  // screen (but no error thrown that's detectable by this test).
+  private static final String CLEARKEY_RESPONSE =
+      "{\"keys\":"
+          + "[{"
+          + "\"kty\":\"oct\","
+          + "\"k\":\"Y8tfcYTdS2iaXF_xHuajKA\","
+          + "\"kid\":\"zX65_4jzTK6wYYWwACTkwg\""
+          + "}],"
+          + "\"type\":\"temporary\"}";
+
+  @Test
+  public void clearkeyPlayback() throws Exception {
+    MockWebServer mockWebServer = new MockWebServer();
+    mockWebServer.enqueue(new MockResponse().setResponseCode(200).setBody(CLEARKEY_RESPONSE));
+    mockWebServer.start();
+
+    MediaItem mediaItem =
+        new MediaItem.Builder()
+            .setUri("asset:///media/drm/sample_fragmented_clearkey.mp4")
+            .setDrmConfiguration(
+                new MediaItem.DrmConfiguration.Builder(C.CLEARKEY_UUID)
+                    .setLicenseUri(mockWebServer.url("license").toString())
+                    .build())
+            .build();
+    AtomicReference<SimpleExoPlayer> player = new AtomicReference<>();
+    ConditionVariable playbackComplete = new ConditionVariable();
+    AtomicReference<PlaybackException> playbackException = new AtomicReference<>();
+    getInstrumentation()
+        .runOnMainSync(
+            () -> {
+              player.set(new ExoPlayer.Builder(getInstrumentation().getContext()).build());
+              player
+                  .get()
+                  .addListener(
+                      new Player.Listener() {
+                        @Override
+                        public void onPlaybackStateChanged(@Player.State int playbackState) {
+                          if (playbackState == Player.STATE_ENDED) {
+                            playbackComplete.open();
+                          }
+                        }
+
+                        @Override
+                        public void onPlayerError(PlaybackException error) {
+                          playbackException.set(error);
+                          playbackComplete.open();
+                        }
+                      });
+              player.get().setMediaItem(mediaItem);
+              player.get().prepare();
+              player.get().play();
+            });
+
+    playbackComplete.block();
+    getInstrumentation().runOnMainSync(() -> player.get().release());
+    getInstrumentation().waitForIdleSync();
+    assertThat(playbackException.get()).isNull();
+  }
+}