public void testByteSource_size_ofDirectory() throws IOException {
    try (FileSystem fs = Jimfs.newFileSystem(Configuration.unix())) {
      Path dir = fs.getPath("dir");
      Files.createDirectory(dir);

      ByteSource source = MoreFiles.asByteSource(dir);

      assertThat(source.sizeIfKnown()).isAbsent();

      assertThrows(IOException.class, () -> source.size());
    }
  }

          .put(FloatBuffer.class, FloatBuffer.allocate(0))
          .put(DoubleBuffer.class, DoubleBuffer.allocate(0))
          .put(File.class, new File(""))
          .put(ByteSource.class, ByteSource.empty())
          .put(CharSource.class, CharSource.empty())
          .put(ByteSink.class, NullByteSink.INSTANCE)
          .put(CharSink.class, NullByteSink.INSTANCE.asCharSink(UTF_8))

import java.io.InputStream;
import java.util.Random;

/**
 * A byte source for testing that has configurable behavior.
 *
 * @author Colin Decker
 */
public final class TestByteSource extends ByteSource implements TestStreamSupplier {

  private final byte[] bytes;
  private final ImmutableSet<TestOption> options;

  private boolean inputStreamOpened;
  private boolean inputStreamClosed;

import java.io.InputStream;
import java.util.Random;

/**
 * A byte source for testing that has configurable behavior.
 *
 * @author Colin Decker
 */
public final class TestByteSource extends ByteSource implements TestStreamSupplier {

  private final byte[] bytes;
  private final ImmutableSet<TestOption> options;

  private boolean inputStreamOpened;
  private boolean inputStreamClosed;

          .put(FloatBuffer.class, FloatBuffer.allocate(0))
          .put(DoubleBuffer.class, DoubleBuffer.allocate(0))
          .put(File.class, new File(""))
          .put(ByteSource.class, ByteSource.empty())
          .put(CharSource.class, CharSource.empty())
          .put(ByteSink.class, NullByteSink.INSTANCE)
          .put(CharSink.class, NullByteSink.INSTANCE.asCharSink(UTF_8))

    suite.addTestSuite(FilesTest.class);
    return suite;
  }

  public void testRoundTripSources() throws Exception {
    File asciiFile = getTestFile("ascii.txt");
    ByteSource byteSource = Files.asByteSource(asciiFile);
    assertSame(byteSource, byteSource.asCharSource(UTF_8).asByteSource(UTF_8));
  }

  public void testToByteArray() throws IOException {
    File asciiFile = getTestFile("ascii.txt");

    assertFreshInstanceReturned(
        ByteArrayOutputStream.class, OutputStream.class,
        Writer.class, StringWriter.class,
        PrintStream.class, PrintWriter.class);
    assertEquals(ByteSource.empty(), ArbitraryInstances.get(ByteSource.class));
    assertEquals(CharSource.empty(), ArbitraryInstances.get(CharSource.class));
    assertNotNull(ArbitraryInstances.get(ByteSink.class));
    assertNotNull(ArbitraryInstances.get(CharSink.class));

   */
  public static ByteSource asByteSource(Path path, OpenOption... options) {
    return new PathByteSource(path, options);
  }

  @IgnoreJRERequirement // *should* be redundant with the one on MoreFiles itself
  private static final class PathByteSource extends
      ByteSource
  {

    private static final LinkOption[] FOLLOW_LINKS = {};

   * equivalent to providing the {@link StandardOpenOption#READ READ} option.
   */
  public static ByteSource asByteSource(Path path, OpenOption... options) {
    return new PathByteSource(path, options);
  }

  private static final class PathByteSource extends
      ByteSource
  {

    private static final LinkOption[] FOLLOW_LINKS = {};

    private final Path path;

      }
      return url;
    }

    /**
     * Returns a {@link ByteSource} view of the resource from which its bytes can be read.
     *
     * @throws NoSuchElementException if the resource cannot be loaded through the class loader,
     *     despite physically existing in the class path.
     * @since 20.0
     */
    public final ByteSource asByteSource() {
      return Resources.asByteSource(url());
    }