public NebulaCheck.IGen <Test> ItErrorsWhenCharTypesIsNone() =>
from charType in Gen.Choose(
Gen.Int32().LessThanEqual(0).Select(x => (GalaxyCheck.Gen.CharType)x),
Gen.Int32().GreaterThan((int)GalaxyCheck.Gen.CharType.All).Select(x => (GalaxyCheck.Gen.CharType)x))
from seed in DomainGen.Seed()
from size in DomainGen.Size()
select Property.ForThese(() =>
{
var gen = GalaxyCheck.Gen.Char(charType);
Action action = () => gen.SampleOne(seed: seed, size: size);
action.Should()
.Throw <GalaxyCheck.Exceptions.GenErrorException>()
.WithMessage("Error while running generator CharGen: 'charType' was not a valid flag value");
});