To become really good at anything takes a lot of practice. Apprenticeships and formal mentoring, common in medieval times, are rare today. To create quality code we need solid practices like Test Driven Development and Pair Programming or Mobbing. In this software craftsmanship workshop attendees practiced those skills on in a code kata.

1. So#ware Cra#smanship
Workshop
Bal$more So+ware Prac$ces and Pa2erns November 29, 2017
Camille Bell
cbell@CamilleBellConsul$ng.com
Twi2er @agilecamille
www.slideshare.net/Camille_Bell

2. So/ware Cra/smanship
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• Tradi8onally cra/smen prac8ced a lot
• Tradi8onally cra/smen worked under masters,
who guided them in their cra/
• Doctors s8ll work as appren8ces under masters in
their internships and residencies
• But so/ware developers don't have a tradi8on of
prac8ce mastering our cra/
• Code Dojos where we prac8ce TDD, Refactoring
and Pairing can fill this gap

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Test Driven Development Ensures Quality

4. Develop in Baby Steps
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• Write a 8ny test
• Watch it fail
• Write only enough code
to make it pass - KISS
• Watch it pass
• If the code gets messy,
refactor in baby steps
• Repeat

5. 3 Rules of Test Driven Development
1. You are not allowed to write any produc8on code unless
it is to make a failing unit test pass.
2. You are not allowed to write any more of a unit test than
is sufficient to fail; and compila8on failures are failures.
3. You are not allowed to write any more produc8on code
than is sufficient to pass the one failing unit test.
With tests you are in control; without tests you aren’t!
Bob Mar8n - The Three Rules of TDD
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6. Test Driven Development Feedback Loop
Write a test for
new low level
func8onality
Run the test and
watch it fail
(no code = test fails)
Write just enough
code to make the
test pass
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Run the test and
watch it pass
Clean up
complex or
messy code
Run test again
to make sure it
s8ll passes
Check in
Code &
Tests
Check in
Code &
Tests

7. Simplified TDD Flow
(o/en called Red-Green-Refactor
Write a failing unit test
for new func8onality
Write just enough
code to pass test
Refactored code must
also pass tests,
no new func8onality
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TDD is Deep Inside Code: Tes8ng at Unit Level

8. • Programmers restructure system by improving the design of exis8ng code
without changing its behavior
– to remove duplica8on, improve communica8on, simplify, or add flexibility
• Refactoring is not random change, instead it’s driven by learning from our
tests and from iden8fying and fixing code smells
• DRY (Don’t Repeat Yourself)
• Refactoring can occur just prior or just a/er wri8ng new code
• Test, code, refactor, re-test
– Very short cycles – refactor in baby steps
Refactoring
When fixing bugs, write a Red test, BEFORE fixing the bug. Test will run Green when bug fixed.
When working with legacy code make sure to write automated tests BEFORE refactoring code,
If tests didn’t exist.
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9. Ping Pong Pairing
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Shared
Computer
Mary Tom
Write a failing test
Make test pass
Write a failing test
Make test pass
Write a failing test
Make test pass
etc.
Make test pass
Write a failing test
Make test pass
Write a failing test
Make test pass
Write a failing test
etc.
Refactor as needed

10. Mob Programming
• Whole team works together
• On the same thing
• At the same 8me
• In the same space
• Using the same computer
• Driver rotates
• Everyone par8cipates
• Great for training & prac8ce
• Great for collabora8on
• Everyone up to speed faster
• Some teams mob always, others frequently
• Features delivered faster – single piece flow /wo handoffs
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1

11. Live FizzBuzz Code Kata
1 2 Fizz 4 Buzz Fizz
7 8 Fizz Buzz 11
Fizz 13 14 FizzBuzz …
Implement FizzBuzz using TDD
like you really mean it
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12. Some Kata References
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• The Coding Dojo Handbook
Available in PDF from Lean Pub
hmps://leanpub.com/codingdojohandbook
• Search for katas available online (such as):
• Bowling Game Kata (Uncle Bob's classic)
• Red Pencil Promo8on Kata (Messy Business Rules)
• Credit Card Number Validator
• Ordered Jobs Kata
• and many more

13. Camille Bell
Agile Technical & Process Coaching
Retrospec8ves
Agile Boot Camps
Agile Training
Updated Slides
or just to chat about things agile
cbell@CamilleBellConsul$ng.com