public void NegativeAtomTest()
{
DiceParser parser = Setup("-4d8");
DiceParser.SignedAtomContext context = parser.signedAtom();
DiceVisitor visitor = new DiceVisitor();
Atom result = (Atom)visitor.VisitSignedAtom(context);
result.IsDiceGroup.Should().BeTrue();
result.Sign.Should().Be(AtomSign.Minus);
result.DiceGroupInstance.Should().BeEquivalentTo(new DiceGroup(new List <Dice> {
new Dice(8), new Dice(8), new Dice(8), new Dice(8)
}));
}