'Override some configuration values.
The keyword arguments are the names of configuration options to
override and their values.
If a group argument is supplied, the overrides are applied to
the specified configuration option group.
All overrides are automatically cleared at the end of the current
test by the fixtures cleanup process.'

def config(self, **kw):

    group = kw.pop('group', None)
    for (k, v) in kw.items():
        CONF.set_override(k, v, group)
