'The given credentials are accepted by all the checkers, and give
the expected C{avatarID}s'

@defer.inlineCallbacks
def test_positive(self):

    for chk in self.getCheckers():
        for (cred, avatarId) in self.getGoodCredentials():
            r = (yield chk.requestAvatarId(cred))
            self.assertEqual(r, avatarId)
