testing revisited - outside-in

Transcript

1. Testing Revisited: Driving Implementation with Outside-in Specs Thursday, June 21, 12
2. Testing isn’t about verification, per se Thursday, June 21, 12
3. It’s a design tool Thursday, June 21, 12
4. An outline Thursday, June 21, 12
5. Executable system specification Thursday, June 21, 12
6. Red Green Refactor Thursday, June 21, 12
7. 1) Write a spec Thursday, June 21, 12
8. 1) Write a spec See it fail Thursday, June 21, 12
9. 2) Write enough code to make it pass Thursday, June 21, 12
10. 2) Write enough code to make it pass Make it green Thursday, June 21, 12
11. 3) Refactor the implementation and/or specs Thursday, June 21, 12
12. 3) Refactor the implementation and/or specs Clean the code, reduce duplication Thursday, June 21, 12
13. http://jakegoulding.com/blog/2011/10/10/learned-about-testing-last-year/ Thursday, June 21, 12
14. 1) Write an acceptance test Thursday, June 21, 12
15. 1a) Write a spec Thursday, June 21, 12
16. 1b) Write enough code to make it pass Thursday, June 21, 12
17. 1c) Refactor the implementation and/or specs Thursday, June 21, 12
18. 2) Write enough unit tests and code to pass the acceptance test Thursday, June 21, 12
19. 3) Refactor Thursday, June 21, 12
20. 4) Repeat Thursday, June 21, 12
21. Sometimes, we want to isolate the item under test from another dependency Thursday, June 21, 12
22. A dependency is any external piece of code the item under test relies on or collaborates with Thursday, June 21, 12
23. When a dependency is expensive or difficult to use, it may be a good idea to swap it out for a test double Thursday, June 21, 12
24. Test doubles: stubs and mocks Thursday, June 21, 12
25. stub: a “dumb” stand-in for a real object that responds to messages (methods), sometimes returning canned responses Thursday, June 21, 12
26. Used when we want to isolate the code under test from uncertainty or costly execution Thursday, June 21, 12
27. mock: a stand-in for a real object that expects to receive messages (methods) and provides testing verification Thursday, June 21, 12
28. Used when we want to test (verify) that the code under test collaborates properly with its depedencies Thursday, June 21, 12
29. Random thoughts Thursday, June 21, 12
30. Testing is hard - especially BDD/TDD Thursday, June 21, 12
31. Well, it’s easy. It’s just subtle. Thursday, June 21, 12
32. Practice, practice, practice. Thursday, June 21, 12
33. People do it “wrong”. Often. Thursday, June 21, 12
34. They will think they’re doing it right. Or at least, doing it less wrong than they are. Thursday, June 21, 12
35. Testing is a religion - especially TDD/BDD Thursday, June 21, 12
36. Testing is a religion - especially TDD/BDD People will evangelize. Thursday, June 21, 12
37. Testing is a religion - especially TDD/BDD People will evangelize. And they’re wrong. Thursday, June 21, 12
38. Read. Learn. Practice, practice, practice. Thursday, June 21, 12
39. Example: Add refeeds to simple_feed Include “refeeded” count Thursday, June 21, 12
40. Exercise: Add show/hide item to simple_feed Add a link on items the user owns to hide them, or to show them for hidden items. Thursday, June 21, 12