<PackageReference Include="NUnit" Version="3.0.0" />

NaNConstraint

public class NaNConstraint : Constraint
NaNConstraint tests that the actual value is a double or float NaN
namespace NUnit.Framework.Constraints { public class NaNConstraint : Constraint { public override string Description => "NaN"; public override ConstraintResult ApplyTo<TActual>(TActual actual) { return new ConstraintResult(this, actual, (((object)actual) is double && double.IsNaN((double)(object)actual)) || (((object)actual) is float && float.IsNaN((float)(object)actual))); } } }