1. Lessons learned from testability failures1

2. Defining testability 2

3. I don’t like hard rules at all. I think they’re all bullshit.
―Ed Catmull 3

4. My personal definition
Unit-testable code
Multiple deployments
Introspection

5. War stories 5

6. Opera Link: Origins 6

7. Challenges Coordinate different teams Decide who has the final word
Clarify expected behaviour
Control unintended changes
Find the source of each bug

8. Solutions Document “obvious” details Write server testsuite
Log traffic on client
Log traffic on server

9. My Opera: from legacy to modern project9

10. First steps for My Opera
Opera browser user community
Social networking
Blogs, albums, forums, groups...
Very old project
Many years without testers
Hostile to testing

11. Solutions Removal of testing roadblocks Functional tests
Continuous integration
More functional tests
Heavy refactoring
Unit tests

12. Opera Link Strikes Back12

13. Opera Link in Mini redux
Client reimplementation
UI-centric testing
The protocol is the buggy bit!

14. Solutions Convince people it was important Mobile tester tools
Ability to switch Link server
Fake server for client testing

15. You have to fight for testability15

16. Why? I hear you ask 16

17. Glad you asked that question17

18. Testability is the only way to scale18

19. Testability and scaling
Allows for good tests
Allows for tests when needed
Shows how systems work
Lowers barrier to entry
Helps isolating root causes

20. The more testable, the higher quality20

21. The more testable, the higher quality
More testability, more tests
More tests, less bugs
...more features
...more refactoring
...more quality

22. Testability doesn't come for free22

23. Testability doesn't come for free
“If you can use it, you can test it”

24. WRONG

25. Testability doesn't come for free
“If you can use it, you can test it”
Repeatability
Automation-friendliness
Multiple deployments
Introspection

26. Closing thoughts 26

27. Some advice Think about what takes time
Think about what you don't know
Think of the children developers!
Teach by example
Show the results

28. Conclusions Untestability is a roadblock For testing and development
Tester heroics can be bad
Support testers, not only end-users
Opacity is the enemy

29. Questions? 29

30. Picture credits U.S. Army:
Gene Driskell:
Joe Shlabotnik:
Dave Morris:
Marcin Wichary:
Joshua Rappeneker:
Sam Ilic:
Andy Bullock: 30