Introduction to unit testing and mocking as seen in a galaxy far away...

1. The Star Wars Version
Gil Zilberfeld
Unit Testing

2. Bugs
How do we deal
with them?

3. xUnit Frameworks
• Test Identification
• Test Runner
• Asserts

4. .NET xUnit Frameworks
• NUnit
• MSTest
• xUnit
• MbUnit

5. Demo

6. Why Unit Test?
• Low TCO
• Small setup
overhead
• It’s not a bug if
it’s caught before
QA
• Go faster
• Quick feedback
• Knowing your
code works
• Confidence to
change your code
• Quicker than
debugging

7. The death spiral
• Tests are slow
• Stop running tests
• Stop writing tests
• Back to square one

8. People write millions of
lines of legacy code
every day!

9. Testing legacy code
• Tests are slow
• Require big setup
• Maybe impossible to run
• Slow to debug

10. Isolation and Mocking
• Let you test your code for different
scenarios, by faking the
dependencies
• As long as your code is ready for it

11. Demo: Hand-Rolled Mocks

12. .NET Mocking Frameworks
• Open-source
• Commercial

13. Demo: Mocking Framework

14. Coverage…
… and other
Jedi mind
tricks

15. Test Driven Development

16. Demo

17. Benefits
• Same Tools
• Better Coverage
• Less debugging
• Better Design
Think before your code!

18. But…
• Requires discipline
• Works better for greenfield
projects
• Not for everyone

20. Agile Adoption

22. Working software
• Automated builds
• Automatic build
• Run unit tests
• Run integration tests
• Unit tests and TDD
Over comprehensive documentation

23. Guidelines
• Unit testing is a team
sport
• Where to start?
• Scaffolding

24. Guidelines
• Naming
• Reviewing
• AAA

25. Guidelines
• Refactoring
• Readability
• Coverage
• Organization

26. www.typemock.com
typemock.com/blog
@typemock
www.gilzilberfeld.com
gilz@typemock.com
@gil_zilberfeld
Questions?

27. Death star explosion
probability calculator
• Only Luke can shoot correctly
• Explode if core temperature > 500
• 1000 X-Wings
• Probability of Luke being hit depends on the
other X-Wings
p(success) = 0.3(X-Wings)
• Probability of X-Wing surviving degrades in
time
p(survival) = 1/t2
• Calculate Luke's hitting probability every 100
time units