@Test
  public void testLookup_absolute_notExists() throws IOException {
    try {
      lookup("/a/b");
      fail();
    } catch (NoSuchFileException expected) {
    }

    try {
      lookup("/work/one/foo/bar");
      fail();
    } catch (NoSuchFileException expected) {
    }

    try {
      lookup("$c/d");
      fail();
    } catch (NoSuchFileException expected) {
    }

    try {
      lookup("$a/b/c/d/e");
      fail();
    } catch (NoSuchFileException expected) {
    }
  }
This path service is for unix-like paths, with the exception that it recognizes $ and ! as
roots in addition to /, allowing for up to three roots. When creating a {@linkplain
PathType#toUriPath URI path}, we prefix the path with / to differentiate between a path like
"$foo/bar" and one like "/$foo/bar". They would become "/$foo/bar" and "//$foo/bar"
respectively.
jimfs/src/test/java/com/google/common/jimfs/FileTreeTest.java