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Jdojo@Gbg Introduction

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Fredrik Wendt
Fredrik Wendt

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.

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JDojo jsolutions.se
Bugs
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"
What solution?
IBM & Microsoft Report ● 40 - 90% fewer bugs discovered during testing ● 15 - 35% more time spent on development
TDD vs Traditional Testing Doesn't remove the need for regular, traditional testing: ● Exploratory testing ● QA testing ● User Interface testing ● Performance testing ● ...
Test-Driven Developmemt Kent Beck on TDD: I'm not a great programmer, I'm just a good programmer with great habits.
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
Another Take ● write test first ● write smallest possible implementation ● clean up ➔ no "dead" code - it's all covered ➔ nice API - designed outside in
Baby Steps ● as small as possible ● as large as is comfortable ● experience of TDD ● technology knowledge ● boldness ● understanding of the problem domain
3A ● Arrange ● Act ● Assert
Benefits ● More confident ● More productive ● More reliable ● More agile
Drawbacks ● More code to maintain ● Takes longer ● Easy to learn, but harder to master
JDojo@Gbg A safe environment to learn coding skills such as Test-driven Development and writing clean code
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.
The Coder's Dojo Concept presented at XP 2005 by Laurent Bossavi and Emmanuel Gaillot
Coding Dojo ● A moderator presents a kata ● Solve the kata, and ... ● Learn from others, teach what you know ● Short retrospective
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
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
JDojo@Gbg Fredrik Wendt jsolutions.se
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

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Jdojo@Gbg Introduction

  • 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"
  • 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
  • 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