Testutils: Add missing Javadoc + Misc cleanup

PiperOrigin-RevId: 278835106

library/core/src/test/java/com/google/android/exoplayer2/database/VersionTableTest.java

@@ -38,7 +38,7 @@ public class VersionTableTest {
 
   @Before
   public void setUp() {
-    databaseProvider = TestUtil.getTestDatabaseProvider();
+    databaseProvider = TestUtil.getInMemoryDatabaseProvider();
     database = databaseProvider.getWritableDatabase();
   }
 

library/core/src/test/java/com/google/android/exoplayer2/extractor/ogg/OggExtractorTest.java

@@ -15,7 +15,6 @@
  */
 package com.google.android.exoplayer2.extractor.ogg;
 
-import static com.google.common.truth.Truth.assertThat;
 
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.android.exoplayer2.testutil.ExtractorAsserts;
@@ -59,7 +58,7 @@ public final class OggExtractorTest {
             OggTestData.buildOggHeader(0x02, 0, 1000, 1),
             TestUtil.createByteArray(7), // Laces
             new byte[] {0x01, 'v', 'o', 'r', 'b', 'i', 's'});
-    assertThat(sniff(data)).isTrue();
+    assertSniff(data, /* expectedResult= */ true);
   }
 
   @Test
@@ -69,7 +68,7 @@ public final class OggExtractorTest {
             OggTestData.buildOggHeader(0x02, 0, 1000, 1),
             TestUtil.createByteArray(5), // Laces
             new byte[] {0x7F, 'F', 'L', 'A', 'C'});
-    assertThat(sniff(data)).isTrue();
+    assertSniff(data, /* expectedResult= */ true);
   }
 
   @Test
@@ -77,13 +76,13 @@ public final class OggExtractorTest {
     byte[] data =
         TestUtil.joinByteArrays(
             OggTestData.buildOggHeader(0x02, 0, 1000, 0x00), new byte[] {'O', 'p', 'u', 's'});
-    assertThat(sniff(data)).isFalse();
+    assertSniff(data, /* expectedResult= */ false);
   }
 
   @Test
   public void testSniffFailsInvalidOggHeader() throws Exception {
     byte[] data = OggTestData.buildOggHeader(0x00, 0, 1000, 0x00);
-    assertThat(sniff(data)).isFalse();
+    assertSniff(data, /* expectedResult= */ false);
   }
 
   @Test
@@ -93,16 +92,17 @@ public final class OggExtractorTest {
             OggTestData.buildOggHeader(0x02, 0, 1000, 1),
             TestUtil.createByteArray(7), // Laces
             new byte[] {0x7F, 'X', 'o', 'r', 'b', 'i', 's'});
-    assertThat(sniff(data)).isFalse();
+    assertSniff(data, /* expectedResult= */ false);
   }
 
   @Test
   public void testSniffFailsEOF() throws Exception {
     byte[] data = OggTestData.buildOggHeader(0x02, 0, 1000, 0x00);
-    assertThat(sniff(data)).isFalse();
+    assertSniff(data, /* expectedResult= */ false);
   }
 
-  private boolean sniff(byte[] data) throws InterruptedException, IOException {
+  private void assertSniff(byte[] data, boolean expectedResult)
+      throws InterruptedException, IOException {
     FakeExtractorInput input =
         new FakeExtractorInput.Builder()
             .setData(data)
@@ -110,6 +110,6 @@ public final class OggExtractorTest {
             .setSimulateUnknownLength(true)
             .setSimulatePartialReads(true)
             .build();
-    return TestUtil.sniffTestData(OGG_EXTRACTOR_FACTORY.create(), input);
+    ExtractorAsserts.assertSniff(OGG_EXTRACTOR_FACTORY.create(), input, expectedResult);
   }
 }

library/core/src/test/java/com/google/android/exoplayer2/offline/DownloadManagerTest.java

@@ -81,7 +81,7 @@ public class DownloadManagerTest {
     uri2 = Uri.parse("http://abc.com/media2");
     uri3 = Uri.parse("http://abc.com/media3");
     dummyMainThread = new DummyMainThread();
-    downloadIndex = new DefaultDownloadIndex(TestUtil.getTestDatabaseProvider());
+    downloadIndex = new DefaultDownloadIndex(TestUtil.getInMemoryDatabaseProvider());
     downloaderFactory = new FakeDownloaderFactory();
     setUpDownloadManager(100);
   }

library/core/src/test/java/com/google/android/exoplayer2/upstream/cache/CachedContentIndexTest.java

@@ -334,7 +334,7 @@ public class CachedContentIndexTest {
   }
 
   private CachedContentIndex newInstance() {
-    return new CachedContentIndex(TestUtil.getTestDatabaseProvider());
+    return new CachedContentIndex(TestUtil.getInMemoryDatabaseProvider());
   }
 
   private CachedContentIndex newLegacyInstance() {

library/core/src/test/java/com/google/android/exoplayer2/upstream/cache/CachedRegionTrackerTest.java

@@ -66,7 +66,7 @@ public final class CachedRegionTrackerTest {
     tracker = new CachedRegionTracker(cache, CACHE_KEY, CHUNK_INDEX);
     cacheDir =
         Util.createTempDirectory(ApplicationProvider.getApplicationContext(), "ExoPlayerTest");
-    index = new CachedContentIndex(TestUtil.getTestDatabaseProvider());
+    index = new CachedContentIndex(TestUtil.getInMemoryDatabaseProvider());
   }
 
   @After

library/core/src/test/java/com/google/android/exoplayer2/upstream/cache/SimpleCacheSpanTest.java

@@ -51,7 +51,7 @@ public class SimpleCacheSpanTest {
   public void setUp() throws Exception {
     cacheDir =
         Util.createTempDirectory(ApplicationProvider.getApplicationContext(), "ExoPlayerTest");
-    index = new CachedContentIndex(TestUtil.getTestDatabaseProvider());
+    index = new CachedContentIndex(TestUtil.getInMemoryDatabaseProvider());
   }
 
   @After

library/core/src/test/java/com/google/android/exoplayer2/upstream/cache/SimpleCacheTest.java

@@ -322,7 +322,7 @@ public class SimpleCacheTest {
   @Test
   public void testExceptionDuringEvictionByLeastRecentlyUsedCacheEvictorNotHang() throws Exception {
     CachedContentIndex contentIndex =
-        Mockito.spy(new CachedContentIndex(TestUtil.getTestDatabaseProvider()));
+        Mockito.spy(new CachedContentIndex(TestUtil.getInMemoryDatabaseProvider()));
     SimpleCache simpleCache =
         new SimpleCache(
             cacheDir, new LeastRecentlyUsedCacheEvictor(20), contentIndex, /* fileIndex= */ null);

library/dash/src/test/java/com/google/android/exoplayer2/source/dash/offline/DownloadManagerDashTest.java

@@ -97,7 +97,7 @@ public class DownloadManagerDashTest {
 
     fakeStreamKey1 = new StreamKey(0, 0, 0);
     fakeStreamKey2 = new StreamKey(0, 1, 0);
-    downloadIndex = new DefaultDownloadIndex(TestUtil.getTestDatabaseProvider());
+    downloadIndex = new DefaultDownloadIndex(TestUtil.getInMemoryDatabaseProvider());
     createDownloadManager();
   }
 

library/dash/src/test/java/com/google/android/exoplayer2/source/dash/offline/DownloadServiceDashTest.java

@@ -112,7 +112,7 @@ public class DownloadServiceDashTest {
     dummyMainThread.runTestOnMainThread(
         () -> {
           DefaultDownloadIndex downloadIndex =
-              new DefaultDownloadIndex(TestUtil.getTestDatabaseProvider());
+              new DefaultDownloadIndex(TestUtil.getInMemoryDatabaseProvider());
           final DownloadManager dashDownloadManager =
               new DownloadManager(
                   ApplicationProvider.getApplicationContext(),

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

@@ -467,6 +467,7 @@ public final class ActionSchedule {
       return apply(new ThrowPlaybackException(tag, exception));
     }
 
+    /** Builds the schedule. */
     public ActionSchedule build() {
       CallbackAction callbackAction = new CallbackAction(tag);
       apply(callbackAction);

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

@@ -46,6 +46,29 @@ public final class ExtractorAsserts {
   private static final String UNKNOWN_LENGTH_EXTENSION = ".unklen" + DUMP_EXTENSION;
 
   /**
+   * Asserts that {@link Extractor#sniff(ExtractorInput)} returns the {@code expectedResult} for a
+   * given {@code input}, retrying repeatedly when {@link SimulatedIOException} is thrown.
+   *
+   * @param extractor The extractor to test.
+   * @param input The extractor input.
+   * @param expectedResult The expected return value.
+   * @throws IOException If reading from the input fails.
+   * @throws InterruptedException If interrupted while reading from the input.
+   */
+  public static void assertSniff(
+      Extractor extractor, FakeExtractorInput input, boolean expectedResult)
+      throws IOException, InterruptedException {
+    while (true) {
+      try {
+        assertThat(extractor.sniff(input)).isEqualTo(expectedResult);
+        return;
+      } catch (SimulatedIOException e) {
+        // Ignore.
+      }
+    }
+  }
+
+  /**
    * Asserts that an extractor behaves correctly given valid input data. Can only be used from
    * Robolectric tests.
    *
@@ -164,7 +187,7 @@ public final class ExtractorAsserts {
         .setSimulatePartialReads(simulatePartialReads).build();
 
     if (sniffFirst) {
-      assertThat(TestUtil.sniffTestData(extractor, input)).isTrue();
+      assertSniff(extractor, input, /* expectedResult= */ true);
       input.resetPeekPosition();
     }
 

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

@@ -33,7 +33,6 @@ import com.google.android.exoplayer2.extractor.Extractor;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
 import com.google.android.exoplayer2.extractor.PositionHolder;
 import com.google.android.exoplayer2.extractor.SeekMap;
-import com.google.android.exoplayer2.testutil.FakeExtractorInput.SimulatedIOException;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.util.Assertions;
@@ -50,17 +49,14 @@ public class TestUtil {
 
   private TestUtil() {}
 
-  public static boolean sniffTestData(Extractor extractor, FakeExtractorInput input)
-      throws IOException, InterruptedException {
-    while (true) {
-      try {
-        return extractor.sniff(input);
-      } catch (SimulatedIOException e) {
-        // Ignore.
-      }
-    }
-  }
-
+  /**
+   * Given an open {@link DataSource}, repeatedly calls {@link DataSource#read(byte[], int, int)}
+   * until {@link C#RESULT_END_OF_INPUT} is returned.
+   *
+   * @param dataSource The source from which to read.
+   * @return The concatenation of all read data.
+   * @throws IOException If an error occurs reading from the source.
+   */
   public static byte[] readToEnd(DataSource dataSource) throws IOException {
     byte[] data = new byte[1024];
     int position = 0;
@@ -77,6 +73,14 @@ public class TestUtil {
     return Arrays.copyOf(data, position);
   }
 
+  /**
+   * Given an open {@link DataSource}, repeatedly calls {@link DataSource#read(byte[], int, int)}
+   * until exactly {@code length} bytes have been read.
+   *
+   * @param dataSource The source from which to read.
+   * @return The read data.
+   * @throws IOException If an error occurs reading from the source.
+   */
   public static byte[] readExactly(DataSource dataSource, int length) throws IOException {
     byte[] data = new byte[length];
     int position = 0;
@@ -91,22 +95,49 @@ public class TestUtil {
     return data;
   }
 
+  /**
+   * Equivalent to {@code buildTestData(length, length)}.
+   *
+   * @param length The length of the array.
+   * @return The generated array.
+   */
   public static byte[] buildTestData(int length) {
     return buildTestData(length, length);
   }
 
+  /**
+   * Generates an array of random bytes with the specified length.
+   *
+   * @param length The length of the array.
+   * @param seed A seed for an internally created {@link Random source of randomness}.
+   * @return The generated array.
+   */
   public static byte[] buildTestData(int length, int seed) {
     return buildTestData(length, new Random(seed));
   }
 
+  /**
+   * Generates an array of random bytes with the specified length.
+   *
+   * @param length The length of the array.
+   * @param random A source of randomness.
+   * @return The generated array.
+   */
   public static byte[] buildTestData(int length, Random random) {
     byte[] source = new byte[length];
     random.nextBytes(source);
     return source;
   }
 
-  public static String buildTestString(int maxLength, Random random) {
-    int length = random.nextInt(maxLength);
+  /**
+   * Generates a random string with the specified maximum length.
+   *
+   * @param maximumLength The maximum length of the string.
+   * @param random A source of randomness.
+   * @return The generated string.
+   */
+  public static String buildTestString(int maximumLength, Random random) {
+    int length = random.nextInt(maximumLength);
     StringBuilder builder = new StringBuilder(length);
     for (int i = 0; i < length; i++) {
       builder.append((char) random.nextInt());
@@ -129,6 +160,12 @@ public class TestUtil {
     return byteArray;
   }
 
+  /**
+   * Concatenates the provided byte arrays.
+   *
+   * @param byteArrays The byte arrays to concatenate.
+   * @return The concatenated result.
+   */
   public static byte[] joinByteArrays(byte[]... byteArrays) {
     int length = 0;
     for (byte[] byteArray : byteArrays) {
@@ -143,24 +180,28 @@ public class TestUtil {
     return joined;
   }
 
+  /** Returns the bytes of an asset file. */
   public static byte[] getByteArray(Context context, String fileName) throws IOException {
     return Util.toByteArray(getInputStream(context, fileName));
   }
 
+  /** Returns an {@link InputStream} for reading from an asset file. */
   public static InputStream getInputStream(Context context, String fileName) throws IOException {
     return context.getResources().getAssets().open(fileName);
   }
 
+  /** Returns a {@link String} read from an asset file. */
   public static String getString(Context context, String fileName) throws IOException {
     return Util.fromUtf8Bytes(getByteArray(context, fileName));
   }
 
-  public static Bitmap readBitmapFromFile(Context context, String fileName) throws IOException {
+  /** Returns a {@link Bitmap} read from an asset file. */
+  public static Bitmap getBitmap(Context context, String fileName) throws IOException {
     return BitmapFactory.decodeStream(getInputStream(context, fileName));
   }
 
-  public static DatabaseProvider getTestDatabaseProvider() {
-    // Provides an in-memory database.
+  /** Returns a {@link DatabaseProvider} that provides an in-memory database. */
+  public static DatabaseProvider getInMemoryDatabaseProvider() {
     return new DefaultDatabaseProvider(
         new SQLiteOpenHelper(
             /* context= */ null, /* name= */ null, /* factory= */ null, /* version= */ 1) {