Matt van Horn's slides from his talk at the Automated Testing SF meetup in February 2015.

1. Testing the Sad Paths

2. About Me
• 20 years of developing web apps
• Doing TDD/BDD since 2001
• Working with Ruby for the last 8 years

3. Teespring
• ~ 100,000 lines of code in the web app
• ~ 5,000 Requests / 800 pages per minute
• ~ 7 million shirts sold in 2014
• Real people making real money

4. Teespring
• We try to TDD as much as possible
• We do serious code review
• We use a CI Server to test pull requests
• We also do manual QA before deploying
• (And, one other thing - we’re hiring!)

5. Some Tools We Use
• Ruby/Rails/(and JS) Stack
• Rspec
• Capybara
• Webmock/VCR
• SimpleCov

6. What Do We Test?

8. The Sad Path

9. The Sad Path
• Happy paths are usually tested and built first
• Sad paths can be overlooked
• Many users will find the sad path

11. Your QA team
They often deal with the sad paths while manual testing

12. Error Handling
• Defensive Coding
• Handling expected problems
• Logging/Tracking error information
• “Exceptional Ruby” covers this topic really well

13. Failure Modes

14. Three Types of Failure
• User does something wrong
• System does something wrong
• Transient - overloaded, slow, unavailable, etc.

15. Testing for User Errors

18. Things to Consider
• What constitutes valid vs. invalid input?
• Where can invalid input possibly enter the
system?
• How do you deal with invalid input in other parts
if the system?

19. Logic Errors

23. Things to Consider
• Almost any part of your system can fail.
• Handling vs. preventing failure
• Nil is a tenacious enemy
• How will you recover from errors?

24. Transient Errors

27. Things to Consider
• Is it even worth retrying?
• Retrying forever is probably a bad thing.
• How do you communicate to users to come back
later?
• How do you isolate the failure to a small area?

28. Questions?

29. Links
• http://rspec.info/
• https://cukes.info/
• https://github.com/jnicklas/capybara
• https://github.com/bblimke/webmock
• https://github.com/vcr/vcr
• https://github.com/colszowka/simplecov
• http://exceptionalruby.com/