protected void assertDirectoryExists(File targetdir, String pattern) {
   DirectoryScanner ds = new DirectoryScanner();
   ds.setBasedir(targetdir);
   ds.setIncludes(new String[] {pattern});
   ds.scan();
   Assert.assertEquals(
       targetdir.getAbsolutePath() + "/" + pattern, 1, ds.getIncludedDirectories().length);
   Assert.assertTrue(
       targetdir.getAbsolutePath() + "/" + pattern,
       new File(targetdir, ds.getIncludedDirectories()[0]).exists());
 }