test AddMethod_ZeroLengthInput_ReturnsZero done
Test 2: one length input should return equivalent value
Test 3 two length input returns sum
Test4: any length input return sum
Test 5: duplicate delimiters throws exception
hooked up view controller button click method to the calculator
Test 6,7 : handleCustomDelimiters,  NegativeNumbersInput_ThrowsExpectedException