new SuccessorsFunction<File>() {
        @Override
        public Iterable<File> successors(File file) {
          // check isDirectory() just because it may be faster than listFiles() on a non-directory
          if (file.isDirectory()) {
            File[] files = file.listFiles();
            if (files != null) {
              return Collections.unmodifiableList(Arrays.asList(files));
            }

      } catch (SecurityException e) {
        logger.warning("Cannot access " + file + ": " + e);
        // TODO(emcmanus): consider whether to log other failure cases too.
        return;
      }
      if (file.isDirectory()) {
        scanDirectory(file, builder);
      } else {
        scanJar(file, scannedUris, builder);
      }
    }

    private void scanJar(

        }
      } finally {
        out.close();
      }
    } finally {
      in.close();
    }
  }

  @CanIgnoreReturnValue
  private boolean delete(File file) {
    if (file.isDirectory()) {
      File[] files = file.listFiles();
      if (files != null) {
        for (File f : files) {
          if (!delete(f)) {
            return false;
          }
        }
      }
    }

      Files.createSymbolicLink(symlinkToFile, file);

      assertTrue(MoreFiles.isDirectory().apply(symlinkToDir));
      assertFalse(MoreFiles.isRegularFile().apply(symlinkToDir));

      assertFalse(MoreFiles.isDirectory().apply(symlinkToFile));
      assertTrue(MoreFiles.isRegularFile().apply(symlinkToFile));

      assertFalse(MoreFiles.isDirectory(NOFOLLOW_LINKS).apply(symlinkToDir));

        }
      } finally {
        out.close();
      }
    } finally {
      in.close();
    }
  }

  @CanIgnoreReturnValue
  private boolean delete(File file) {
    if (file.isDirectory()) {
      File[] files = file.listFiles();
      if (files != null) {
        for (File f : files) {
          if (!delete(f)) {
            return false;
          }
        }
      }
    }

  }

  private static File pickAnyJarFile() throws IOException {
    for (ClassPath.LocationInfo location :
        ClassPath.locationsFrom(ClassPathTest.class.getClassLoader())) {
      if (!location.file().isDirectory() && location.file().exists()) {
        return location.file();
      }
    }
    throw new AssertionError("Failed to find a jar file");
  }

      assertThrows(IllegalStateException.class, Files::createTempDir);
      return;
    }
    File temp = Files.createTempDir();
    try {
      assertThat(temp.exists()).isTrue();
      assertThat(temp.isDirectory()).isTrue();
      assertThat(temp.listFiles()).isEmpty();
      File child = new File(temp, "child");
      assertThat(child.createNewFile()).isTrue();
      assertThat(child.delete()).isTrue();

  }

  private static File pickAnyJarFile() throws IOException {
    for (ClassPath.LocationInfo location :
        ClassPath.locationsFrom(ClassPathTest.class.getClassLoader())) {
      if (!location.file().isDirectory() && location.file().exists()) {
        return location.file();
      }
    }
    throw new AssertionError("Failed to find a jar file");
  }

  @AndroidIncompatible // Path (for symlink creation)

      assertThrows(IllegalStateException.class, Files::createTempDir);
      return;
    }
    File temp = Files.createTempDir();
    try {
      assertThat(temp.exists()).isTrue();
      assertThat(temp.isDirectory()).isTrue();
      assertThat(temp.listFiles()).isEmpty();
      File child = new File(temp, "child");
      assertThat(child.createNewFile()).isTrue();
      assertThat(child.delete()).isTrue();

  public void testPredicates() throws IOException {
    File asciiFile = getTestFile("ascii.txt");
    File dir = asciiFile.getParentFile();
    assertTrue(Files.isDirectory().apply(dir));
    assertFalse(Files.isFile().apply(dir));

    assertFalse(Files.isDirectory().apply(asciiFile));
    assertTrue(Files.isFile().apply(asciiFile));
  }

  /** Returns a root path for the file system. */
  private static File root() {