Add DummyDataSource

A dummy DataSource which provides no data.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=150868950

library/core/src/main/java/com/google/android/exoplayer2/upstream/DummyDataSource.java

+/*
+ * Copyright (C) 2017 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.upstream;
+
+import android.net.Uri;
+import java.io.IOException;
+
+/**
+ * A dummy DataSource which provides no data. {@link #open(DataSpec)} throws {@link IOException}.
+ */
+public final class DummyDataSource implements DataSource {
+
+  public static final DummyDataSource INSTANCE = new DummyDataSource();
+
+  /** A factory that that produces {@link DummyDataSource}. */
+  public static final Factory FACTORY = new Factory() {
+    @Override
+    public DataSource createDataSource() {
+      return new DummyDataSource();
+    }
+  };
+
+  private DummyDataSource() {}
+
+  @Override
+  public long open(DataSpec dataSpec) throws IOException {
+    throw new IOException("Dummy source");
+  }
+
+  @Override
+  public int read(byte[] buffer, int offset, int readLength) throws IOException {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public Uri getUri() {
+    return null;
+  }
+
+  @Override
+  public void close() throws IOException {
+    // do nothing.
+  }
+
+}

library/dash/src/androidTest/java/com/google/android/exoplayer2/source/dash/DashUtilTest.java

@@ -23,10 +23,8 @@ import com.google.android.exoplayer2.source.dash.manifest.AdaptationSet;
 import com.google.android.exoplayer2.source.dash.manifest.Period;
 import com.google.android.exoplayer2.source.dash.manifest.Representation;
 import com.google.android.exoplayer2.source.dash.manifest.SegmentBase.SingleSegmentBase;
-import com.google.android.exoplayer2.testutil.FakeDataSource;
-import com.google.android.exoplayer2.upstream.DataSource;
+import com.google.android.exoplayer2.upstream.DummyDataSource;
 import com.google.android.exoplayer2.util.MimeTypes;
-import java.io.IOException;
 import java.util.Arrays;
 import junit.framework.TestCase;
 
@@ -37,25 +35,25 @@ public final class DashUtilTest extends TestCase {
 
   public void testLoadDrmInitDataFromManifest() throws Exception {
     Period period = newPeriod(newAdaptationSets(newRepresentations(newDrmInitData())));
-    DrmInitData drmInitData = DashUtil.loadDrmInitData(newDataSource(), period);
+    DrmInitData drmInitData = DashUtil.loadDrmInitData(DummyDataSource.INSTANCE, period);
     assertEquals(newDrmInitData(), drmInitData);
   }
 
   public void testLoadDrmInitDataMissing() throws Exception {
     Period period = newPeriod(newAdaptationSets(newRepresentations(null /* no init data */)));
-    DrmInitData drmInitData = DashUtil.loadDrmInitData(newDataSource(), period);
+    DrmInitData drmInitData = DashUtil.loadDrmInitData(DummyDataSource.INSTANCE, period);
     assertNull(drmInitData);
   }
 
   public void testLoadDrmInitDataNoRepresentations() throws Exception {
     Period period = newPeriod(newAdaptationSets(/* no representation */));
-    DrmInitData drmInitData = DashUtil.loadDrmInitData(newDataSource(), period);
+    DrmInitData drmInitData = DashUtil.loadDrmInitData(DummyDataSource.INSTANCE, period);
     assertNull(drmInitData);
   }
 
   public void testLoadDrmInitDataNoAdaptationSets() throws Exception {
     Period period = newPeriod(/* no adaptation set */);
-    DrmInitData drmInitData = DashUtil.loadDrmInitData(newDataSource(), period);
+    DrmInitData drmInitData = DashUtil.loadDrmInitData(DummyDataSource.INSTANCE, period);
     assertNull(drmInitData);
   }
 
@@ -81,11 +79,4 @@ public final class DashUtilTest extends TestCase {
         new byte[]{1, 4, 7, 0, 3, 6}));
   }
 
-  private static DataSource newDataSource() {
-    // TODO: Use DummyDataSource when available.
-    FakeDataSource fakeDataSource = new FakeDataSource();
-    fakeDataSource.getDataSet().newDefaultData().appendReadError(new IOException("Unexpected"));
-    return fakeDataSource;
-  }
-
 }