public void SubtractTwoIntegers()
 {
     SubtractExpression expr = new SubtractExpression(new ConstantExpression(2), new ConstantExpression(1));
     Assert.IsNotNull(expr.LeftExpression);
     Assert.IsNotNull(expr.RightExpression);
     Assert.AreEqual(1, expr.Evaluate(null));
 }
        public void SubtractIntegerFromDouble()
        {
            SubtractExpression expr = new SubtractExpression(new ConstantExpression(2.5), new ConstantExpression(1));

            Assert.AreEqual(2.5 - 1, expr.Evaluate(null));
        }
        public void SubtractTwoDoubles()
        {
            SubtractExpression expr = new SubtractExpression(new ConstantExpression(2.5), new ConstantExpression(3.7));

            Assert.AreEqual(2.5 - 3.7, expr.Evaluate(null));
        }
        public void SubtractDoubleFromInteger()
        {
            SubtractExpression expr = new SubtractExpression(new ConstantExpression(1), new ConstantExpression(2.5));

            Assert.AreEqual(1 - 2.5, expr.Evaluate(null));
        }