"Files.asCharSink[File, Charset, APPEND]",
            SourceSinkFactories.appendingFileCharSinkFactory()));
    suite.addTestSuite(FilesTest.class);
    return suite;
  }

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