'This is a paranoid test wrapper, that calls C{meth} 2 times, clear the
cache, and calls it 2 other times. It\'s supposed to ensure that the
plugin system behaves correctly no matter what the state of the cache
is.'

def _withCacheness(meth):

    @functools.wraps(meth)
    def wrapped(self):
        meth(self)
        meth(self)
        self._clearCache()
        meth(self)
        meth(self)
    return wrapped
