This is a Code Kata to exercise Test-Driven Development (TDD).
Original site: https://osherove.com/tdd-kata-1.
-
Write a failing test
-
Make the test pass
-
Refactor the code. After refactoring, all tests must still pass.
-
Goto step 1.
-
Start with Step 1.
-
Work incrementally. Do not expand a step before the previous one is solved.
-
Only test for correct inputs. There is no need to test for invalid inputs (e.g.
null) in this Kata.
Step 1
Create a new method named int add(String number) in class StringCalculator.
-
The method can take 0, 1 or 2 numbers, and will return their sum (for an empty string it will return 0). Example inputs:
""or""or"1,2" -
Start with the simplest test case of an empty string, and move to one and two numbers
-
Remember to solve things as simply as possible, so that you force yourself to write tests you did not think about.
-
Remember to refactor after each passing test.
Step 2
Allow the add method to handle an unknown amount of numbers.
Step 3
Allow the add method to handle new lines between numbers (instead of commas).
-
The following input is ok:
"1\n2,3"(will equal 6) -
The following input is NOT ok:
"1,\n"(not need to prove it - just clarifying)
Step 4
Support different delimiters
-
To change a delimiter, the beginning of the string will contain a separate line that looks like this:
"//[delimiter]\n[numbers…]"
for example"//;\n1;2"should return three where the default delimiter is;. -
The first line is optional. All existing scenarios should still be supported.
Step 5
Calling add with a negative number will throw an exception "negatives not allowed" - and the negative that was passed. If there are multiple negatives, show all of them in the exception message.
Stop here if you are a beginner. Continue if you can finish the steps so far in less than 30 minutes.
Step 6
Numbers bigger than 1000 should be ignored, so adding 2 + 1001 = 2
Step 7
Delimiters can be of any length with the following format: "//[delimiter]\n". For example: "//[***]\n1***2***3" should return 6
Step 8
Allow multiple delimiters like this: "//[delim1][delim2]\n".
For example "//[*][%]\n1*2%3" should return 6.
Step 9
Make sure you can also handle multiple delimiters with length longer than one char.