*
   * @param sources the sources to concatenate
   * @return a {@code ByteSource} containing the concatenated data
   * @since 15.0
   */
  public static ByteSource concat(Iterable<? extends ByteSource> sources) {
    return new ConcatenatedByteSource(sources);
  }

  /**
   * Concatenates multiple {@link ByteSource} instances into a single source. Streams returned from

  public void testConcat() throws IOException {
    ByteSource b1 = ByteSource.wrap(new byte[] {0, 1, 2, 3});
    ByteSource b2 = ByteSource.wrap(new byte[0]);
    ByteSource b3 = ByteSource.wrap(new byte[] {4, 5});

    byte[] expected = {0, 1, 2, 3, 4, 5};

    assertArrayEquals(expected, ByteSource.concat(ImmutableList.of(b1, b2, b3)).read());
    assertArrayEquals(expected, ByteSource.concat(b1, b2, b3).read());

  public void testConcat() throws IOException {
    ByteSource b1 = ByteSource.wrap(new byte[] {0, 1, 2, 3});
    ByteSource b2 = ByteSource.wrap(new byte[0]);
    ByteSource b3 = ByteSource.wrap(new byte[] {4, 5});

    byte[] expected = {0, 1, 2, 3, 4, 5};

    assertArrayEquals(expected, ByteSource.concat(ImmutableList.of(b1, b2, b3)).read());
    assertArrayEquals(expected, ByteSource.concat(b1, b2, b3).read());

    @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

    @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

 * 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

  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());
    }
  }

    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");

  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))