public void AbsoluteValue_ToString()
        {
            const int reference = 3;

            var expression = ExpressionFactory.AbsoluteValue(reference);

            Assert.AreEqual("|3|", expression.ToString());
        }
        public void AbsoluteValue_Positive()
        {
            const int reference = 5;

            var expression = ExpressionFactory.AbsoluteValue(reference);
            var result     = expression.GetConstantValue();

            Assert.AreEqual(reference, result);
        }