public static void IntLiftInfinityTest()
{
var intPlus = new Monoid <int>(0, (x, y) => x + y);
var intPlusInf = intPlus.LiftMonoidWithInfinity();
Assert.True(intPlusInf.Neutral.HasValue);
Assert.Equal(0, intPlusInf.Neutral.Value());
var r = intPlusInf.Op(Maybe.Just(3), Maybe.Just(8));
Assert.True(r.HasValue);
Assert.Equal(11, r.Value());
r = intPlusInf.Op(Maybe.Nothing <int>(), Maybe.Just(8));
Assert.False(r.HasValue);
r = intPlusInf.Op(Maybe.Just(3), Maybe.Nothing <int>());
Assert.False(r.HasValue);
r = intPlusInf.Op(Maybe.Nothing <int>(), Maybe.Nothing <int>());
Assert.False(r.HasValue);
}