def test_call_on_shared(self):
        """Supervise an operation that is being made on a share."""
        # create other user
        other_user = make_storage_user(username='user2')

        # make a share from default user to other user and accept it
        root_id = self.gw.get_root().id
        share = self.gw.make_share(
            root_id, 'hi', user_id=other_user.id, readonly=False)
        share = StorageUserGateway(other_user).accept_share(share.id)

        # do the operation in the gw from the share
        shared_gw = ReadWriteVolumeGateway(other_user, share=share)
        shared_gw.make_file(root_id, 'filename')

        # check that the metric informed is storage, from default user,
        # as she is the owner of the volume where the node was created
        for informed in self.informed:
            if informed[0] == 'make_file':
                self.assertIsInstance(informed[1], float)
                break
        else:
            self.fail('Timing was not informed for this method.')