Macaulay2, version 1.2.99
with packages: ConwayPolynomials, Elimination, IntegralClosure, LLLBases, PrimaryDecomposition, ReesAlgebra, SchurRings, TangentCone

i1 : A = ZZ/101[a,b]/(a*b)

o1 = A

o1 : QuotientRing

i2 : L = toField A

o2 = L

o2 : PolynomialRing

i3 : assert try (1/(a+b); false) else true
--error message bumped: a non unit was found in a ring declared to be a field
