This document discusses test-driven development (TDD) and its benefits. It notes that TDD can find bugs earlier and reduce costs, though traditional testing is still needed. TDD involves writing a test first, then code to pass the test, and refactoring code while ensuring all tests remain passing. Practicing TDD through coding "katas" or exercises in a "dojo" setting can improve skills over time through repetition. While TDD takes more initial time, the benefits are more confidence, productivity, reliability and agility in the long run.

1. JDojo
jsolutions.se

2. Bugs

3. The Problem
● Bugs are costly
● Fixing bugs reported
from testers costs
even more
● Fixing bugs reported
from en users costs
even more than "even
more"

4. What solution?

5. IBM & Microsoft Report
● 40 - 90% fewer bugs
discovered during
testing
● 15 - 35% more time
spent on
development

6. TDD vs Traditional Testing
Doesn't remove the
need for regular,
traditional testing:
● Exploratory testing
● QA testing
● User Interface testing
● Performance testing
● ...

7. Test-Driven Developmemt
Kent Beck on TDD:
I'm not a great
programmer,
I'm just a good
programmer with
great habits.

8. Red, Green, Refactor
● Write a test, get it to
compile, get a red bar
● Quickly make the test
pass, get a green bar
● Refactor, "clean
code", run tests
frequently - the "bar"
should stay green

9. Another Take
● write test first
● write smallest possible
implementation
● clean up
➔ no "dead" code - it's all
covered
➔ nice API - designed
outside in

10. Baby Steps
● as small as possible
● as large as is
comfortable
● experience of TDD
● technology knowledge
● boldness
● understanding of the
problem domain

11. 3A
● Arrange
● Act
● Assert

12. Benefits
● More confident
● More productive
● More reliable
● More agile

13. Drawbacks
● More code to
maintain
● Takes longer
● Easy to learn, but
harder to master

14. JDojo@Gbg
A safe environment to
learn coding skills such
as
Test-driven Development
and writing
clean code

15. Dave Thomas - Kata
"Pragmatic Dave":
A kata is an exercise in
karate where you repeat
a form many, many
times, making little
improvements in each.

16. The Coder's Dojo
Concept presented at XP 2005 by
Laurent Bossavi and Emmanuel Gaillot

17. Coding Dojo
● A moderator
presents a kata
● Solve the kata, and ...
● Learn from others,
teach what you know
● Short retrospective

18. Kata
● Small programming
exercise - 1-2 hours
● Start from scratch
● Strictly test-driven
● Next time, start over
and try new approach
● Practice until you
master the kata

19. Dojo Rules
● Don't criticize until we
have a green bar
● Strict usage of TDD
● Everyone's obligation
to point out any non-
TDD behaviour

20. JDojo@Gbg
Fredrik Wendt
jsolutions.se

21. All vector art comes from Gnome base icon set, which is licensed under LGPL.
download.gnome.org/sources/gnome-icon-theme
Man on vacuum cleaner from
tpp-bloggen.
Firebug logotype from
getfirebug.com
Baby Steps photo from
seandreilinger at flickr.com
Picture of Dave Thomas from
x180 at flickr.com
Picture of Kent Beck from
Three Rivers Institute web site