def setup_volume(self):
        """Setup the volume used for this test case."""
        # create another user and share a folder with self.user
        sharer = make_storage_user(
            username='sharer', max_storage_bytes=2000)
        self.owner = sharer
        root = StorageObject.objects.get_root(sharer._user)
        rw_node = root.make_subdirectory('WriteMe')
        # share a node with the user with modify access
        rw_share = self.factory.make_share(
            subtree=rw_node, shared_to=self.user._user, name='WriteShare',
            access=Share.MODIFY)
        rw_share.accept()
        share_dao = SharedDirectory(rw_share, by_user=sharer)
        self.vgw = ReadWriteVolumeGateway(self.user, share=share_dao)
        self.root = StorageObject.objects.get(id=self.vgw.get_root().id)
        self.file = self.root.make_file(
            'TheName', content_blob=self.factory.make_content_blob(),
            mimetype='fakemime')