public void ExpressionWithSum()
        {
            var inputString = "11+12+25+1000";

            var calculator = new StringCalculation.StringCalculator();

            Assert.AreEqual(1048, calculator.CalculateString(inputString));
        }
        public void ExpressionWithSubstraction()
        {
            var inputString = "300-40-333-1";

            var calculator = new StringCalculation.StringCalculator();

            Assert.AreEqual(-74, calculator.CalculateString(inputString));
        }
        public void SimpleTest()
        {
            var inputString = "1+2-3+4-5";

            var calculator = new StringCalculation.StringCalculator();

            Assert.AreEqual(-1, calculator.CalculateString(inputString));
        }