def test_change_ring(self): R = PuiseuxSeriesRing(QQ, 'x') S = R.change_ring(QQbar) self.assertEqual(R.base_ring(), QQ) self.assertEqual(S.base_ring(), QQbar) T = R.change_ring(SR) self.assertEqual(T.base_ring(), SR) B = QQ['a,b'] U = R.change_ring(B) self.assertEqual(U.base_ring(), B)