This presentation explains WHY Test Driven Development matters and what are some of the infinite advantages of this great technique for programming a cleaner and higher quality code.

9. Sam Serpoosh
@masihjesus
http://masihjesus .wordpress.com
https://github.com/Sam-Serpoosh
http://linkedin.com /in/samserpoosh

13. “programmers have more in
common with chefs than
with desk jockeys like
accountants or attorneys.”
~Greg Baugues

14.  Nobody
wants
to wash the
dishes!

17. 
Test-First programming.

Kent Beck used it in Chrysler C3 project
in 1996.

TDD in XP(eXtreme Programming)
practices.

the most important and useful approach

20. Enumerable
Select method in
Ruby!
• Invokes the block passing in
successive elements from
self, returning an array containing
those elements for which the block
returns a true value (equivalent to
Enumerable#select).

21. it “fetches green squares” do
green_square =
squares.select {|square| square.color ==
green}
green_square.color.should == green
end

22. 
Tests tell the code
how to look like from
its user’s perspective

It is more a design
technique and tests
are great side-effects!

You feel the pain
first when it’s hard
to use!

23. 
You are not allowed to write any
production code unless you have a failing
unit test and that production code is about
to make it pass.

You are not allowed to write any more of a
unit test than is sufficient to fail; and
compilation failures are failures.

You are not allowed to write any more
production code than is sufficient to pass
the one failing unit test.

24. Kent Beck defines:

Never write a single line of code unless
you have a failing automated test.

Eliminate Duplication(DRY, Don’t
Repeat Yourself)

25. 




Red (Automated test fails)
Green (Automated test pass)
Refactor (eliminate
duplication, eliminate the mess, clean
the code)
Sushi Chef Metaphor
Red
Dirty Dishes of dinner
Green
Refactor

26. Start
Write a
test
See it fails
because there’s
no dev code
Run the Test
Write (just enough)
Dev Code to compile
See it fails
because no logic
is implemented
Run the Test
Write (just enough)
Dev Code to compile
See the
Test pass
Run the Test
Refactoring

27. •
Knowing about execution of system all the
times.
•
Short cycles (even 10 minutes is too long).
•
A minute ago all their code worked. (Pick a
Random Person)

29. •
Thousands of unit tests will be
produced.
•
Can run them anytime we want.
•
Whenever we make any kind of change.
•
Executable and live documentation of
system instead of pile of papers.

30. •
There’s a test as an example to show
you what you want!
•
They CANNOT be out of date
•
Make the FEAR disappear (Refactoring)

31.  Oh
My God this
code is a mess
I
need to clean this up!
 But I’m not gonna touch it!

32. TDD 
Testable
Decoupled
Decoupling
most important
factor
TDD 
managing dependency better 
DIP

33. •
so much flexible and easy to change.
Software is Soft again! Go ahead and
change!
•
NOT  Fragile, Rigid, Immobile
•

34. TESTS MORE SPECIFIC

CODE MORE GENERAL

35. •
2005 study  TDD  more productive &
increase their confidence.
•
software  much more
flexible, reliable, testable & with great live
documentation.
•
NOT PROFESSIONAL if you don’t do TDD
(~ Uncle Bob, Ron Jeffries, Kent
Beck, etc.)

36. had been a programmer for 3 decades
before I was introduced to TDD. I did not
think anyone could teach me a low level
programming practice that would make a
difference. But when I started TDD, I was
dumbfounded at the effectiveness of the
technique.
~ Robert C. Martin
I

37. Blog posts and articles:

Grand Design by Stephen Hawking &
Leonard Mlodinow
•
http://objectmentor.com/articles
•
http://cleancoder.com/articles
•
http://codebetter.com/articles
•
Code like a chef series!

38. •
Robert C. Martin craftsmanship article
series
•
Uncle Bob on Rules and Benefits of TDD
•
Michael Feathers Synergy between Design
and Testability
•
Jeremy D. Miller Writing Maintainable
Programs series
•
Sarah Gray on Visualizing Enumerable

39. Books:
• TDD by Example (Kent Beck)
• Clean Code (Robert C. Martin)
• Agile Software Development
Principles, Patterns, Practices (Robert C.
Martin)
• Working Effectively With Legacy Code
(Michael Feathers)
• Growing Object-Oriented Software Guided
by Tests (Steve Freeman & Nat Pryce)
• Refactoring (Martin Fowler)

40. Lectures And Conferences:
•
•
•
•
•
•
•
Clean Code I, II (Robert C. Martin)
Are you a Professional? (Robert C. Martin)
Synergy between Design and Testability
(Michael Feathers)
Effective Software Development (Alistair
Cockburn)
Clean, Testable Code (Misko Hevery)
Clean Coders Videos (Clean Code Matters)
Destroy All Software (Gary Bernhardt)