Brian Swan - TDD Pitfalls

Test Driven Development is now more than 10 years old yet is still causing controversy as a development technique. Common pitfalls can reduce the value of Test Driven Development, this talk will highlight those pitfalls to help teams and individuals get the maximum benefit from this powerful technique.

Transcript

1. TDD Pitfalls Brian Swan @bgswan
2. A quick reminder
3. Ron Jeffries Clean code that works
4. Kent Beck, Test Driven Development By Example Write a failing automated test before you write any code. Remove duplication.
5. Kent Beck, Test Driven Development By Example Write a failing automated test before you write any code. Remove duplication. production ^
6. Coders At Work
7. Jamie Zawinski
8. The Duct Tape Fallout http://www.joelonsoftware.com/items/2009/09/23.html
9. what I’m going to cut out is the stuff that’s not absolutely critical. And unit tests are not critical. If there’s no unit tests the customer isn’t going to complain about that. Jamie Zawinski, Coders At Work p34
10. Uncle Bob Martin
11. As for Joel’s consistent dismissal of unit testing, he’s just wrong about that. Unit testing (done TDD style) does not slow you down, it speeds you up. Bob Martin, http://blog.objectmentor.com/articles/2009/09/24/the-duct-tape- programmer
12. The Flight of the Startup
13. 1.Taxi – get in position. 2.Takeoff – apply power in one general direction until airborne. 3.Climb – manage steep growth at full power. 4.Cruise – make steady progress towards clear goals. Kent Beck, http://www.threeriversinstitute.org/blog/?p=251
14. Practices like developer testing that were useful in moderation in the takeoff phase and became a matter of survival in the climb phase now help increase profitability by reducing cost. Kent Beck, http://www.threeriversinstitute.org/blog/?p=251
15. Not recognising what phase you’re in. Pitfall #1
16. Lets talk about tools
17. Ruby
18. RSpec Minitest test-unit Riot Bacon Wrong Shindo testrocket rubydoctest Testy Micronaut Lemon test_inline dtf Detest kintama Cucumber Steak Turnip Spinach Coulda Stella Unencumbered Stories Filet saki rspec-mocks Mocha Rr Flexmock Stump Facon Cross-stub simple_mock Factory Girl Machinist Fabrication FixtureBuilder Object daddy dm-sweatshop Blueprints Fixjour spawn FixtureReplacement sham Transactionata Faker Forgery ffaker Randexp Random data Capybara Webrat capybara-webkit Culerity Celerity Selenium-client Akephalos watir-webdriver poltergeist headless Selenium-on-rails Watir Polonium Guard Watchr Autotest Kicker Infinity Test tconsole tork
19. Not evaluating the cost vs benefit of new tools Pitfall #2
20. The Test Pyramid Automated UI Integration Unit
21. The Test Cuboid Integration Automated UI Unit
22. Automated UI Integration Unit Inverted Test Pyramid
23. Automated UI Integration Unit Manual Test Ice-cream Cone http://watirmelon.com/2012/01/31/introducing-the-software-testing-ice-cream-cone/
24. Too many end-to-end tests Pitfall #3
25. Tests as documentation
26. Test Scripts http://www.concordion.org/Technique.html
27. Specifications http://www.concordion.org/Technique.html
28. Too much noise, not enough signal Pitfall #4
29. Mock, mock. Who’s there?
30. http://worabeans.blogspot.co.uk/2010/08/mock-jms-spring-junit4-mockrunner.html A Pathological Example
31. Mocking too much Pitfall #5
32. Code Smells
33. Test Pain
34. Not listening to the tests Pitfall #6
35. Code Coverage
37. Coverage as a goal Pitfall #7
38. Slow Running Tests
39. Don’t split up you tests into slow and fast, split up you app into other apps or libs. Splitting the tests is just ignoring the problem plus people will just stop looking at the slow test. Daniel Worthington-Bodart, http://dan.bodar.com/2012/02/28/crazy- fast-build-times-or-when-10-seconds-starts-to-make-you-nervous/
40. Not tackling slow tests Pitfall #8
41. Broken Tests
42. Leaving broken tests Pitfall #9
43. Intermittent Failures
44. The trouble with non-deterministic tests is that when they go red, you have no idea whether its due to a bug, or just part of the non-deterministic behavior. Martin Fowler: http://martinfowler.com/articles/nonDeterminism.html
45. Ignoring intermittent failures Pitfall #10
46. Confidence
47. I get paid for code that works, not for tests, so my philosophy is to test as little as possible to reach a given level of confidence... Kent Beck, http://stackoverflow.com/questions/153234/how-deep-are- your-unit-tests
48. ...Ten or twenty years from now we'll likely have a more universal theory of which tests to write, which tests not to write, and how to tell the difference. In the meantime, experimentation seems in order. Kent Beck, http://stackoverflow.com/questions/153234/how-deep-are- your-unit-tests
49. Thanks Brian Swan @bgswan