EC Tech Meetup May 20, 2014 – Was TDD a QA Coup d’etat?

Tonight is the next installment of  *hands on* for our local group.  With brewskies and Crown Royal.

There will be testing exercises and some TDD kata, and discussing the efficacy of TDD in coding with today’s modern methodologies.

A lot of you have noted there has been a (predictable) backlash against TDD.    My earliest memories of the methodology were of zealot/half coders from QA spitting bologna sandwich bits on our shiny developer faces while they told us we were all wrong about how we thought about software.   I personally worked on sites where directors argued that QA=Developer in a sprint.   Now when I look back I see that part of the evolution as a coup; that QA was trying to take over the development process by trying to argue that the creation process was nothing more than translating requirements and tests to code.  It sounded great in a manifesto . . . . but didn’t work in practice like so many other manifestos.  Eventually, and to this day, non-coding management uses  TDD as an bludgeon for their inquisition — the usual spiral to not so much build software as to set up a CYA network and pre-empt blame.  Good old pre-emptive blame, another Agile methodology.

Then, as now, we have argued TDD is merely a technique for the tool box.  Yes test, but I wasn’t ready to drill a hole into my engine block to test block temps just yet.  And software is not a set of tests, its a set of something that does something – for people.

That aside, the tasks on-hand will be this kata I gleaned from Roy Osherove’s site with many, many thank yous.

String Calculator

The following is a TDD Kata- an exercise in coding, refactoring and test-first, that you should apply daily for at least 15 minutes (I do 30).

Before you start:

  • Try not to read ahead.
  • Do one task at a time. The trick is to learn to work incrementally.
  • Make sure you only test for correct inputs. there is no need to test for invalid inputs for this kata

String Calculator

  1. Create a simple String calculator with a method int Add(string numbers)
    1. The method can take 0, 1 or 2 numbers, and will return their sum (for an empty string it will return 0) for example “” or “1” or “1,2”
    2. Start with the simplest test case of an empty string and move to 1 and two numbers
    3. Remember to solve things as simply as possible so that you force yourself to write tests you did not think about
    4. Remember to refactor after each passing test
  2. Allow the Add method to handle an unknown amount of numbers
  3. Allow the Add method to handle new lines between numbers (instead of commas).
    1. the following input is ok:  “1\n2,3”  (will equal 6)
    2. the following input is NOT ok:  “1,\n” (not need to prove it – just clarifying)
  4. Support different delimiters
    1. 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 ‘;’ .
    2. the first line is optional. all existing scenarios should still be supported
  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.


  6. Numbers bigger than 1000 should be ignored, so adding 2 + 1001  = 2
  7. Delimiters can be of any length with the following format:  “//[delimiter]\n” for example: “//[***]\n1***2***3” should return 6
  8. Allow multiple delimiters like this:  “//[delim1][delim2]\n” for example “//[*][%]\n1*2%3” should return 6.
  9. make sure you can also handle multiple delimiters with length longer than one char

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