@GwtIncompatible
final class MultiInputStream extends InputStream {

  private final Iterator<? extends ByteSource> it;
  private @Nullable InputStream in;

  /**
   * Creates a new instance.
   *
   * @param it an iterator of I/O suppliers that will provide each substream
   */
  public MultiInputStream(Iterator<? extends ByteSource> it) throws IOException {
    this.it = checkNotNull(it);
    advance();
  }

  @Override

    @Override
    public void tearDown() throws IOException {}
  }

  private static class ByteArraySourceFactory implements ByteSourceFactory {

    @Override
    public ByteSource createSource(byte[] bytes) throws IOException {
      return ByteSource.wrap(bytes);
    }

    @Override
    public byte[] getExpected(byte[] bytes) {
      return bytes;
    }

    @Override

  private final TestByteSource byteSource;

  public TestCharSource(String content, TestOption... options) {
    this.byteSource = new TestByteSource(content.getBytes(UTF_8), options);
  }

  @Override
  public boolean wasStreamOpened() {
    return byteSource.wasStreamOpened();
  }

  @Override
  public boolean wasStreamClosed() {
    return byteSource.wasStreamClosed();
  }

  @Override

    S createSink() throws IOException;

    /** Gets the current content of the created sink. */
    T getSinkContents() throws IOException;
  }

  /** Factory for {@link ByteSource} instances. */
  interface ByteSourceFactory extends SourceFactory<ByteSource, byte[]> {}

  /** Factory for {@link ByteSink} instances. */
  interface ByteSinkFactory extends SinkFactory<ByteSink, byte[]> {}

  /** Factory for {@link CharSource} instances. */

 * be an empty line at the end if the contents are terminated with a line separator.
 *
 * <p>Any {@link ByteSource} containing text encoded with a specific {@linkplain Charset character
 * encoding} may be viewed as a {@code CharSource} using {@link ByteSource#asCharSource(Charset)}.
 *
 * <p><b>Note:</b> In general, {@code CharSource} is intended to be used for "file-like" sources

import org.jspecify.annotations.NullUnmarked;

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

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

  private boolean inputStreamOpened;
  private boolean inputStreamClosed;

  private final TestByteSource byteSource;

  public TestCharSource(String content, TestOption... options) {
    this.byteSource = new TestByteSource(content.getBytes(UTF_8), options);
  }

  @Override
  public boolean wasStreamOpened() {
    return byteSource.wasStreamOpened();
  }

  @Override
  public boolean wasStreamClosed() {
    return byteSource.wasStreamClosed();
  }

  @Override

    S createSink() throws IOException;

    /** Gets the current content of the created sink. */
    T getSinkContents() throws IOException;
  }

  /** Factory for {@link ByteSource} instances. */
  interface ByteSourceFactory extends SourceFactory<ByteSource, byte[]> {}

  /** Factory for {@link ByteSink} instances. */
  interface ByteSinkFactory extends SinkFactory<ByteSink, byte[]> {}

  /** Factory for {@link CharSource} instances. */

  private Resources() {}

  /**
   * Returns a {@link ByteSource} that reads from the given URL.
   *
   * @since 14.0
   */
  public static ByteSource asByteSource(URL url) {
    return new UrlByteSource(url);
  }

  /** A byte source that reads from a URL using {@link URL#openStream()}. */
  private static final class UrlByteSource extends ByteSource {

    private final URL url;

  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);
    }
  }