def METHOD_NAME(self):
    g = ConjunctiveGraph()
    h = ConjunctiveGraph()
    g.parse(self.data, format="nquads")
    s1 = set(g.subjects())
    self.data.seek(0)
    h.parse(self.data, format="nquads")
    s2 = set(h.subjects())
    assert s1 != s2