Unit Test After, First and TDD

More and more developers are writing unit test. And that's really great. They are a great way to ensure code's correctness. But writing test after is often difficult : code may not be testable, "it works, why bother with test. Let's do real stuff !",... Testing first could be a solution to those problems. TDD goes further. Unit tests do not only test the code, they become a tool to design a better, cleaner and safer code.

This talk has been given at the ITAKE Unconference (http://www.itakeunconf.com)

Transcript

1. UNIT TEST, TEST FIRST AND TDD / Antoine Vernois @avernois
2. WHO AM I ?
3. DISCLAIMER this is an introduction to unit testing i won't talk about : mocking london style vs. chicago integration test and yes, i will do some over exaggeration :)
4. DEFINITION Unit test a test that verify the smallest piece of an application.
5. QUALITY OF A UNIT TEST Fast Isolated Repeatable Self-validating Timely
6. WHY ? because it's cool ! confidence in your code tests tell what your code do testable and tested code often lead to better design the sooner you find problem, the cheaper you'll solve them
7. TEST AFTER
8. BOWLING TIME !
9. COMMON PROBLEMS Why bother with tests, it just works ! Tests are for people who don’t know how to code ! thecodinglove.com I'm in hurry, I have lot of functionnal to do. I'll write the test later.
10. (BIGGER ?) PROBLEMS we could have write untestable code we have never seen our tests fail ! often, we build test by reverse engeeniring the code
11. TEST FIRST 1. Think what I want to do. 2. Write tests according it. 3. Write code that make all the tests pass. ENJOY.
12. BOWLING TIME !
13. CONFESSION TIME
14. TEST DRIVEN DEVELOPPEMENT 1. Write exactly one failing test 2. Make it pass 3. Make it clean REPEAT
15. TEST DRIVEN DEVELOPPEMENT 1. Red 2. Green 3. Refactor THAT'S ALL !
16. TEST DRIVEN DEVELOPPEMENT GIT VARIANT 1. Red 2. Green 3. git commit 4. Refactor 5. git commit
17. BOWLING TIME !
18. THANK YOU !