try (FileOutputStream fos = new FileOutputStream(testFile)) {
      for (int i = 0; i < 500; i++) {
        fos.write(dummyData);
      }
    }
    try (ReadableByteChannel inChannel = new RandomAccessFile(testFile, "r").getChannel()) {
      ByteStreams.copy(inChannel, outChannel);
    }
    byte[] actual = out.toByteArray();
    for (int i = 0; i < 500 * chunkSize; i += chunkSize) {

    try (FileOutputStream fos = new FileOutputStream(testFile)) {
      for (int i = 0; i < 500; i++) {
        fos.write(dummyData);
      }
    }
    try (ReadableByteChannel inChannel = new RandomAccessFile(testFile, "r").getChannel()) {
      ByteStreams.copy(inChannel, outChannel);
    }
    byte[] actual = out.toByteArray();
    for (int i = 0; i < 500 * chunkSize; i += chunkSize) {