public void PositiveIntValidatesCorrectly(int value, bool isSuccess)
{
Assert.AreEqual(isSuccess, PositiveInt.Create(value).IsSuccess);
var exceptionConstraint = isSuccess.Match <IConstraint>(
t => Throws.Nothing,
f => Throws.TypeOf <ArgumentException>()
);
Assert.That(() => PositiveInt.CreateUnsafe(value), exceptionConstraint);
}