The following is a TDD Kata- an exercise in coding, refactoring and test-first. You can download a more readable version of the Kata here.
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Try not to read ahead.
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Do one task at a time. The trick is to learn to work incrementally.
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Make sure you only test for correct inputs. there is no need to test for invalid inputs for this kata
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Create a simple String calculator with a method signature:
int Add(string numbers)
The method can take up to two numbers, separated by commas, and will return their sum.
for example
“” or “1” or “1,2”
as inputs.Hints:
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Start with the simplest test case of an empty string and move to one and two numbers
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Remember to solve things as simply as possible so that you force yourself to write tests you did not think about
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Remember to refactor after each passing test
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Allow the Add method to handle an unknown amount of numbers
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Allow the Add method to handle new lines between numbers (instead of commas).
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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)
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Support different delimiters
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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‘;’
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the first line is optional. all existing scenarios should still be supported
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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.
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Numbers bigger than 1000 should be ignored, so adding
2 + 1001 = 2
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Delimiters can be of any length with the following format:
“//[delimiter]\n”
for example:“//[***]\n1***2***3” should return 6
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Allow multiple delimiters like this:
“//[delim1][delim2]\n”
for example“//[*][%]\n1*2%3” should return 6
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make sure you can also handle multiple delimiters with length longer than one char