File file = createTempFile();
    // Test
    assertThrows(
        IllegalArgumentException.class,
        () -> Files.map(file, MapMode.READ_WRITE, (long) Integer.MAX_VALUE + 1));
  }

  public void testGetFileExtension() {
    assertThat(Files.getFileExtension(".txt")).isEqualTo("txt");
    assertThat(Files.getFileExtension("blah.txt")).isEqualTo("txt");
    assertThat(Files.getFileExtension("blah..txt")).isEqualTo("txt");

      Files.createSymbolicLink(symlink, fs.getRootDirectories().iterator().next());
      Path file = symlink.resolve("foo");
      MoreFiles.createParentDirectories(file);
    }
  }

  public void testGetFileExtension() {
    assertThat(MoreFiles.getFileExtension(FS.getPath(".txt"))).isEqualTo("txt");
    assertThat(MoreFiles.getFileExtension(FS.getPath("blah.txt"))).isEqualTo("txt");

      Files.createSymbolicLink(symlink, fs.getRootDirectories().iterator().next());
      Path file = symlink.resolve("foo");
      MoreFiles.createParentDirectories(file);
    }
  }

  public void testGetFileExtension() {
    assertThat(MoreFiles.getFileExtension(FS.getPath(".txt"))).isEqualTo("txt");
    assertThat(MoreFiles.getFileExtension(FS.getPath("blah.txt"))).isEqualTo("txt");