TDD 0 to 60 An Introduction in

Test-Driven Developmentin .NETMichael Joseph Kramer

Pillar Technology

http://www.flickr.com/photos/purplepick/2554134479/

What do you mean by “unit test”?

• code tests code

• small

• fast

• independent

http://www.flickr.com/photos/ugocei/6420197/

the whole truthiness

• Anything I can do with a unit test, I can do with a debugger.• It’s an ivory tower activity, not something real businesses do.• Unit testing isn’t for small businesses.• Unit testing isn’t for the enterprise.• We don’t need no stinkin’ unit tests. We have a QA team!• We don’t need no stinkin’ QA team. We have unit tests!• Writing tests will take me longer, which makes it cost more.• Most of the stuff I write isn’t interesting enough for a unit

tests. It’s only for complicated stuff.• Unit testing prevents you from writing crappy software.• Everything I have ever learned about software development is

wrong.

http://www.flickr.com/photos/thelastminute/142252337/

What do I need?

• NUnit

• MbUnit

• MsTest

• xUnit.net

http://www.flickr.com/photos/17258892@N05/2588347668/

http://www.flickr.com/photos/lynac/321100379/

AAA ain’t just the auto club

Arrange – Set it up!Act – Call It!Assert – Verify it worked!

http://www.flickr.com/photos/ethomsen/2815081394//

Is this TDD???

http://www.flickr.com/photos/37612915@N00/350716275/

only refactor green tests!

http://www.flickr.com/photos/jshultz/118841012/

http://http://www.flickr.com/photos/roadsidepictures/469271408//

Weak. My code uses a database...

http://www.flickr.com/photos/helios89/1373343153

Dependencies

• inject the dependency

• replace with a stub

http://www.flickr.com/photos/leecullivan/141114012/

http://www.flickr.com/photos/victius/4064996780/

Why can’t I just go

to the database?

http://www.flickr.com/photos/richpix/1386265680/

Mocking: not just for when your manager out of the room

• a mock knows if your test passed

• behavior, not state

• void methods

• brittle

http://www.flickr.com/photos/mariaclarah/927759528/

http://www.flickr.com/photos/8829172@N02/4010684609/

Mocks aren’t Stubs, abridged

• Stubs vs. Mocks, in a nutshell:

– Stubs: return dummy data

– Mocks: Test passes or fails based on what the method does, not what it returns

– Test Double or Fake: Generic terms for either a mock or stub

I.E., a mock can make a test fail, a stub can’t.

Full Version: http://martinfowler.com/articles/mocksArentStubs.html

http://www.flickr.com/photos/marcobellucci/3534516458/

• Upcoming Webinars: Please visit pillartechnology.com/events

• All of the webinar content is available to your business in a 1-2 day on-site workshop or as a “lunch and learn” format. Please contact us for details.

• Visit www.pillartechnology.com/events to access presentation slides and full archived broadcasts of past webinars.

• Twitter.com/agilesoftware

• Blog: www.pillartechnology.com/blog

• LinkedIn: Join the Agile Enthusiast Group on LinkedIn: http://bit.ly/agilegroup

• YouTube: http://www.youtube.com/user/PillarTechnology

• Phone: (888) 3-pillar

• Web: pillartechnology.com

• Email: info@pillartechnology.com

Our Next Steps