Slides for my talk on TDD, the usual mistakes that developers make when practising TDD, the wider issues in TDD and suggestions how to make TDD work better

1. Common mistakes in TDD -
can you guess?

2. Christos Matskas
https://cmatskas.com
@christosmatskas
https://github.com/cmatskas

3. What is Test Driven Development (TDD)?

4. What TDD isn’t
•TDD tests are not Unit Tests
•TDD tests are not User Acceptance Tests

5. What does TDD have to offer?
• Small pieces of code
• Short feedback loop
• Helps create design specification
• Reduces time to do bug fixes and add new features
• Reduces debugger-driven development
• Makes the code more adaptable

6. Common TDD mistakes
#1
Not using a Mocking Framework

7. Common TDD mistakes
#2
Too much test setup

8. Common TDD mistakes
#3
Asserting everything

9. Common TDD mistakes
#4
Unnecessary testing

10. Unnecessary testing - example
public class StudentService()
{
//….other code ommitted
public Student GetByID(string id)
{
return studentRepository.GetByID(id);
}
}

11. Larger issues with TDD
#1
False confidence

12. Larger issues with TDD
#2
Testing too much is expensive

13. Larger issues with TDD
#3
Test induced architecture damage

14. Larger issues with TDD
#4
Heavy Mocking

15. Larger issues with TDD
#5
TDD in the real world

16. Larger issues with TDD
#6
No everyone can think in TDD terms

17. Make TDD work for you
Use the right tool for the job

18. TDD with Model-View-Controller(MVC)
public Controller UserController()
{
//...other code ommitted
public IHttpViewResult GetAllUsers()
{
return new UserView(userService.GetAllUsers());
}
}

19. Make TDD work for you
• Code-to-test radio => 1:2
• Find the right coverage ratio
• Test should take less time to write than actual code
• Keep clear separation between unit & integration
tests
• Find the best approach to code first (30:70?

20. Questions?