throw new IllegalStateException("More than one source open");
            }
            return new FilterReader(source.openStream()) {
              @Override
              public void close() throws IOException {
                super.close();
                counter[0]--;
              }
            };
          }
        };
    Reader joinedReader = CharSource.concat(reader, reader, reader).openStream();

   * approaches 2 or 3 are used.
   */
  private static final int ZERO_COPY_CHUNK_SIZE = 512 * 1024;

  private ByteStreams() {}

  /**
   * Copies all bytes from the input stream to the output stream. Does not close or flush either
   * stream.
   *
   * <p><b>Java 9 users and later:</b> this method should be treated as deprecated; use the
   * equivalent {@link InputStream#transferTo} method instead.
   *

    Files.copy(i18nFile, temp);
    assertTrue(Files.equal(i18nFile, temp));

    Files.copy(asciiFile, temp);
    RandomAccessFile rf = new RandomAccessFile(temp, "rw");
    rf.writeByte(0);
    rf.close();
    assertEquals(asciiFile.length(), temp.length());
    assertFalse(Files.equal(asciiFile, temp));

    assertTrue(Files.asByteSource(asciiFile).contentEquals(Files.asByteSource(asciiFile)));

/**
 * Options controlling the behavior of sources/sinks/streams for testing.
 *
 * @author Colin Decker
 */
public enum TestOption {
  OPEN_THROWS,
  SKIP_THROWS,
  READ_THROWS,
  WRITE_THROWS,
  CLOSE_THROWS,
  AVAILABLE_ALWAYS_ZERO

    charBuffer = CharBuffer.allocate(bufferSize);
    Java8Compatibility.flip(charBuffer);

    byteBuffer = ByteBuffer.allocate(bufferSize);
  }

  @Override
  public void close() throws IOException {
    reader.close();
  }

  @Override
  public int read() throws IOException {
    return (read(singleByte) == 1) ? UnsignedBytes.toInt(singleByte[0]) : -1;
  }

   *     method
   * @throws IOException if {@code swallowIOException} is false and {@link Flushable#flush} throws
   *     an {@code IOException}.
   * @see Closeables#close
   */
  public static void flush(Flushable flushable, boolean swallowIOException) throws IOException {
    try {
      flushable.flush();
    } catch (IOException e) {
      if (swallowIOException) {

    rootDir = Jimfs.newFileSystem(Configuration.unix()).getPath("/tmp");
    Files.createDirectory(rootDir);
  }

  @Override
  public void tearDown() throws IOException {
    rootDir.getFileSystem().close();
  }

  public void testFileTraverser_emptyDirectory() throws Exception {
    assertThat(MoreFiles.fileTraverser().breadthFirst(rootDir)).containsExactly(rootDir);
  }

  // ClasLoader via its AccessControlContext. It does not seem to be possible to make a
  // URLClassLoader without capturing this reference, and it probably would not be desirable for
  // security reasons anyway. Therefore, the FRQ.close() method provides a way to stop the thread
  // explicitly. This test checks that calling that method does allow an app's ClassLoader to be

    }
  }

  // Avoid infinite recursion if a closeable's close() method throws RejectedExecutionException and
  // is closed using the direct executor.
  public void testCloseThrowsRejectedExecutionException() throws Exception {
    doThrow(new RejectedExecutionException()).when(mockCloseable).close();
    ClosingFuture<Closeable> closingFuture =
        ClosingFuture.submit(

    // Test that listeners added both before and after the value is available
    // get called correctly.
    for (int i = 0; i < 20; i++) {

      // Right in the middle start up a thread to close the latch.
      if (i == 10) {
        new Thread(() -> latch.countDown()).start();
      }

      future.addListener(listenerLatch::countDown, exec);
    }

    assertSame(Boolean.TRUE, future.get());