def test_get_collector_trail_topdir_and_beyond(self):

       config = py.test.config._reparse([self.tmpdir])

       col = config._getcollector(config.topdir)

       trail = config.get_collector_trail(col)

       assert len(trail) == 2

       assert trail[0] == '.'

       assert trail[1] == ()

       col2 = config._getcollector(trail)

       assert col2.fspath == config.topdir

       assert len(col2.listchain()) == 1

       col3 = config._getcollector(config.topdir.dirpath())

       py.test.raises(ValueError, 

->           "config.get_collector_trail(col3)")

   def raises(ExpectedException, *args, **kwargs):

       """ raise AssertionError, if target code does not raise the expected

           exception.

       """

       assert args

       __tracebackhide__ = True 

       if isinstance(args[0], str):

           expr, = args

           assert isinstance(expr, str)

           frame = sys._getframe(1)

           loc = frame.f_locals.copy()

           loc.update(kwargs)

           #print "raises frame scope: %r" % frame.f_locals

           source = py.code.Source(expr)

           try:

->             exec source.compile() in frame.f_globals, loc

               #del __traceback__

               # XXX didn'T mean f_globals == f_locals something special?

               #     this is destroyed here ...

           except ExpectedException:

               return py.code.ExceptionInfo()

       else:

           func = args[0]

           assert callable

           try:

               func(*args[1:], **kwargs)

               #del __traceback__

           except ExpectedException:

               return py.code.ExceptionInfo()

           k = ", ".join(["%s=%r" % x for x in kwargs.items()])

           if k:

               k = ', ' + k

           expr = '%s(%r%s)' %(func.__name__, args, k)

       raise ExceptionFailure(msg="DID NOT RAISE", 

                              expr=args, expected=ExpectedException) 

-> config.get_collector_trail(col3)

   def get_collector_trail(self, collector):

       """ provide a trail relative to the topdir, 

               which can be used to reconstruct the

               collector (possibly on a different host

               starting from a different topdir). 

           """ 

       chain = collector.listchain()

       relpath = chain[0].fspath.relto(self.topdir)

       if not relpath:

           if chain[0].fspath == self.topdir:

               relpath = "."

           else:

               raise ValueError("%r not relative to %s" 

->                      %(chain[0], self.topdir))

       return relpath, tuple([x.name for x in chain[1:]])