The document summarizes a presentation on using LEGO bricks to teach concepts of test-driven development (TDD). The presenters led exercises where participants built LEGO structures to represent code by writing tests first and making the minimum changes to pass each test. They explored TDD practices like the red-green-refactor mantra, pair programming, and refactoring code. Participants worked in groups to build larger projects through an iterative TDD process and demonstrated their work to others. The goal was to experience TDD and software development techniques in a hands-on way through constructing physical models with LEGO.

1. Bryan Beecham and Mike Bowler
TDD with LEGO
Thank you to our Sponsors
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2. Understanding
TDD with LEGO
Bryan Beecham
@BillyGarnet
Mike Bowler
@mike_bowler
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3. Exercise - 1
Open up one LEGO packet
Build a person and a house out of LEGO
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4. Admire your work
Take a photo. Upload to Twitter. Brag to your friends.
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5. Reference
Test-Driven
Development
By Example
Kent Beck
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6. What is the goal of TDD?
It creates clean code that works ~ Ron Jefferies
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7. TDD
It is a predictable way to develop. You know when you
are finished, without having to worry about a long bug
trail.
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8. TDD
It gives you a chance to learn all of the lessons that the
code has to teach you. If you only slap together the first
thing you think of, then you never have time to think of a
second, better thing.
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9. TDD
It improves the lives of the users of your software.
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10. TDD
It lets your teammates count on you, and you on them.
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11. TDD
It feels good to write it.
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12. The Mantra
Red - Green - Refactor
photo from doolwind.com
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13. The Mantra - Red
Write a small test that doesn’t work
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14. The Mantra - Green
Do the minimum to make the test work
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15. The Mantra - Refactor
Eliminate duplication
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16. Exercise - 2
Build a person and a house with TDD
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17. Prepare your environment
Clear the area in front of you. This is your program.
The perfect program!
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18. First Test
Does the person exist? No?
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19. Hurray!!!
We failed the test!
Celebrate! High 5s!
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20. Minimum to pass the test
Add a block. Can that be a person?
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21. Hurray!!!
The person now exists!
Not very impressive but it could represent a person.
We passed the test! We are rocking now!
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22. Refactor
Remove any duplication. In this case we’re good.
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23. Same thing for house
Blah, blah, awesome recreation by speaker...everyone is
extremely impressed and are thinking this might be the
best session of the whole conference.
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24. We need a new test
The house is taller then the person.
Assert.IsTrue(house.height > person.height);
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25. Hurray!!! More Failure
The person is the
same size so we fail
this test.
Well done!
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26. Failure =
Learning Opportunity
If you’re not failing, you’re not learning.
If you’re not learning...
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27. Minimum to pass the test
From the audience this time. Anyone? Bueller?
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28. Hurray!!! - Success
Alright, we passed the test.
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29. Refactor
Still very simple. Still nice and clean.
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30. Software Requirements
Software must do three things:
It must work
It must be understandable
It must be updatable
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31. We need a new test
Is the house wider then the person? No?
We failed another test! Awesome! We are learning a lot
about improvements that are needed to our code.
Let’s do the minimum to pass the test.
Any duplication to remove?
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32. We need a new test
Can your person fit in the house? Yikes! No.
We failed another test! Awesome! We are learning so
much about what our customer needs.
Let’s do the minimum to pass the test.
Any duplication to remove?
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33. Exercise - 3 Partners!
Break into groups of
two for this next
exercise.
When developers do
this we call it Pair
Programming
Berkley photo from the web
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34. New Requirements
Your new program needs to have:
A person
A house
A tree
An animal
A vehicle
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35. Let’s Practice!
Work together and write down a new test
Build minimally pass the test
Repeat (Don’t worry about Refactoring for now)
Here’s a few if you get stuck:
Is the house at least x bricks tall?
Is the tree the same size as the house?
Is the animal smaller than the person?
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36. New Requirements
Your new program needs to have:
A person
A house
A tree
An animal
A vehicle
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37. Review
Let’s take a minute to walk around and look at
everybody’s creations!
Taking breaks and stretching your muscles (eyes, legs,
arms, back) is very important to stay healthy.
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38. Apology
You may have to break your wonderful new structures for
the components for the next section.
Don’t worry, there is more building to come!
Please do take a photo. Remember @BillyGarnet and
@mike_bowler #SDEC13 if you’re tweeting about the
amazing time you’re having!
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39. Refactoring
Refactoring is the process of changing a software system
in such a way that it does not alter the external behaviour
of the code yet improves its internal structure.
~Martin Fowler
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40. Super Fast Break
Stand up and stretch - really, it’s important!
Share something you’ve learned with a neighbour!
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41. Exercise 4 -Team Build
Each table will come up with a large structure with lots of
parts to build. (airport, zoo, amusement park...)
You will be a software team, working in pairs, contributing
to the large team structure (the build) at your table.
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42. Decide on an idea
Shh...don’t tell the other tables.
(Jeopardy music...)
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43. Break it into components
Take a minute to write out a few of the components that
need to be built (product backlog).
Each pair will build a component through TDD.
We will then add the sections to the big project.
Make sure you don’t break your teams tests!
Write your test on paper, fail, then add lego to pass.
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44. Demo time!
A few teams will now present their creation.
Please share the tests that you came up with and point
out the solution.
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45. Review
Test-Driven Development / Design
Refactoring
Pair Programming
A bit of developer speak
Experience working on a software team
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46. Questions?
Bryan Beecham
@BillyGarnet
bbeecham@fusebill.com
Mike Bowler
@mike_bowler
mbowler@gargoylesoftware.com
Please separate the lego bricks into their respective
colours
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47. No really, it’s over
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48. There are no more slides
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49. No trailers
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50. Looking for more?
Check out http://www.humanrefactor.com
Links to HumanRefactoring, and soon more LEGO!
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