AgileAttitudes Article
 
 
 

Vol 01 Issue 13- Beyond Unit Testing

  
 
Back to the list of articles Agile Attitudes Volume 1, Issue 13 Dec. 2, 2004 A free bi-weekly email newsletter Brought to you by Agile Rules consulting www.agilerules.com ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Welcome to Agile Attitudes, a newsletter of ideas, insights and technical tips that help people find better ways to develop software. Feel free to share this with anyone - just be sure you send or print the whole thing, including the copyright notice. Directions for managing your subscription are below. O><O><O><O><O><O Bad news!! The Dec 9 Agile Bazaar meeting hosting Alistair Cockburn had to be canceled. We are deeply sorry if this has caused any inconvenience. O><O><O><O><O><O Beyond Unit Testing by Ron Morsicato I recently read a rather scathing criticism of an agile view- point where the main point was that agile methodologies have too much of an emphasis on unit testing. In the author's mind, by focusing on unit tests, developers are spending an inordinate amount of time cleaning up the simplest of defects, and ignoring the more difficult to detect defects that have to to with the proper collaboration of domains (those collections of units that provide sets of services for other components of the system being built). I do not deny that domain-level and system-level integration testing is important. I wonder why it follows that if you make the effort to ensure each unit has a test, that higher level testing is ignored. I also wonder why the critic believes that good unit tests won't also produce a well-designed system with well-designed domains. When you use test-driven development, you benefit not only from test coverage at the unit level, but also from side effects of a development pattern that leads to better code. The pattern is quite simple - fail, pass, refactor. This sounds strange: is a developer to write bad code first? Of course not; you see the reason you fail is that you write the test first. You test for functionality that doesn't exist yet. (And now you know you will detect a failure.) Then you put in the functionality. You put it in the unit you wrote the test for. But there's another step - and this is the important one - you refactor. (There's that word again.) This is where you ask questions like whether there is a simpler way to achieve this functionality, or if there some coding pattern that's repeating itself, and how to get it in one place. When you make the refactoring a reality, that's when you reap benefits that go beyond simply having an all-inclusive unit test suite. In addition to eliminating duplication, this approach will simplify your architecture by eliminating circular reasoning when it comes to the interdependency of your system components. In other words, it makes those domains truly independent of each other, and will cut down on those domain level defects. That's an overlooked benefit of emphasizing unit testing (using the fail, pass, refactor pattern), and is key to why test driven development produces better code. O><O><O><O><O><O More articles on Agile software topics at http://www.agilerules.com Within our company we have a sub-specialty in embedded systems. Our site has articles on embedded XP and we support a discussion list focused on the use of agile methods for building embedded software. The list signup info is at http://www.agilerules.com/mailinglists.phtml O><O><O><O><O><O To help you get started with in-depth research into Agile Attitudes topics, we have added a Library section to our web site at http://www.agilerules.com/library.phtml Order using our links and receive discounts up to 30%! O><O><O><O><O><O If you enjoyed this issue or found it useful, forward it to a friend! Help spread the word about better ways to build software. 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Send feedback to info@agilerules.com To manage your subscription: http://www.agilerules.com/mailman/listinfo/agileattitudes O><O><O><O><O><O Brought to you by Agile Rules consulting 162 Marrett Road, Lexington MA 02421 Copyright (c) 2004 Agile Rules info@agilerules.com O><O><O><O><O><O Privacy notice: We will not release a subscriber's address to any third party for any reason. This is a strictly opt-in newsletter. No one is ever subscribed without their explicit request. _______________________________________________ AgileAttitudes mailing list AgileAttitudes@agilerules.com http://www.agilerules.com/mailman/listinfo/agileattitudes </plaintext> </td id="bodytable_r1_c3_body"> </tr id="bodytable_r1"> </table id="bodytable">