'Return the test item for a test function.
This writes the source to a python file and runs pytest\'s
collection on the resulting module, returning the test item
for the requested function name.
:param source: The module source.
:param funcname: The name of the test function for which the
Item must be returned.'

def getitem(self, source, funcname='test_func'):

    items = self.getitems(source)
    for item in items:
        if (item.name == funcname):
            return item
    assert 0, ('%r    item    not    found    in    module:\n%s\nitems:    %s' % (funcname, source, items))
