New spike for property based testing

blah.cs

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;


namespace Propern.Specs
{
    [TestClass]
    public class Math_operations
    {
        static Func<int> an_integer = Spec.Given(R => R.Next());
        static Func<int> a_small_integer = Spec.Given(R => R.Next(-10, 10));
        static Func<int> a_small_integer_not_0 = Spec.Given(_ => a_small_integer(), x => x != 0);

        [TestMethod]
        public void Subtract_2_numbers()
        {
            Spec.Given(_ => new { number_to_subtract_from = an_integer(), number_to_subtract_by = a_small_integer() })
                .Times(100)
                .When(givens => givens.number_to_subtract_from - givens.number_to_subtract_by)
                .Assert((givens, result) => Assert.AreEqual(givens.number_to_subtract_by + result, givens.number_to_subtract_from))
                .Check();
        }


        [TestMethod]
        public void Divide_2_numbers()
        {
            Spec.Given(_ => new { number_to_divide = an_integer(), number_to_divide_by = a_small_integer_not_0() })
                .Times(100)
                .When(givens => givens.number_to_divide / givens.number_to_divide_by)
                .Assert((i, o) => Assert.IsTrue(Math.Abs(o * i.number_to_divide_by) <= Math.Abs(i.number_to_divide)))
                .Check();
        }
    }
}