def METHOD_NAME(self):
    obj = PCounter4()
    obj.inc()
    oid = self._storage.new_oid()
    revid1 = self._dostoreNP(oid, data=zodb_pickle(obj))
    obj.inc()
    obj.inc()
    # The effect of committing two transactions with the same
    # pickle is to commit two different transactions relative to
    # revid1 that add two to _value.
    self._dostoreNP(oid, revid=revid1, data=zodb_pickle(obj))
    self.assertRaises(ConflictError,
                      self._dostoreNP,
                      oid, revid=revid1, data=zodb_pickle(obj))