@Test public void readFileTest() throws IOException { final String sentence1 = "This is a sentence."; final String sentence2 = "This is another sentence."; List<String> sentences = Arrays.asList(sentence1, sentence2); DirectorySampleStream directorySampleStream = new DirectorySampleStream(directory.getRoot(), null, false); File tempFile1 = directory.newFile(); FileUtils.writeStringToFile(tempFile1, sentence1); File tempFile2 = directory.newFile(); FileUtils.writeStringToFile(tempFile2, sentence2); try (FileToStringSampleStream stream = new FileToStringSampleStream(directorySampleStream, Charset.defaultCharset())) { String read = stream.read(); Assert.assertTrue(sentences.contains(read)); read = stream.read(); Assert.assertTrue(sentences.contains(read)); } }