def test_collect_listnames_and_back():

       col1 = py.test.collect.Directory(datadir.dirpath())

->     col2 = col1.join(datadir.basename) 

       col3 = col2.join('filetest.py')

       l = col3.listnames()

       assert len(l) == 3

       x = col1._getitembynames(l[1:])

       assert x.name == "filetest.py"

       x = col1._getitembynames("/".join(l[1:]))

       assert x.name == "filetest.py"

       l2 = x.listnames()

       assert len(l2) == 3

   def join(self, name):

       name2items = self.__dict__.setdefault('_name2items', {})

       try:

           res = name2items[name]

       except KeyError:

           p = self.fspath.join(name)

           res = None

           if p.check(file=1): 

               if p.ext == '.py':

                   res = self.Module(p, parent=self) 

               elif p.ext == '.txt':

                   res = self.DoctestFile(p, parent=self)

           elif p.check(dir=1): 

               Directory = py.test.config.getvalue('Directory', p) 

->             res = Directory(p, parent=self) 

           name2items[name] = res 

       return res