Lecture 21: Extreme Programming

Today's Lecture

Lecture on Extreme Programming given by Christian Doerr
- Christian did not prepare slides for this lecture; instead I have converted his notes into slide format to show the topics that were discussed

Customer is Team Member
- Customer is part of the team; Release early, release often
User Stories
- It is often hard to have users write formal specifications
- Requirements are written up in form of "stories"
- These are written on cards, prioritized and implemented (physical artifact)
Refactor often
- Agile projects always take the simplest path
- They just solved today's problems
- You write good code and change it
Imagine being an architect and building a house, what comes first? How do you measure quality?
- Test Driven Development
  - Write tests even before you write code
  - you are always up to date
  - What do tests cover? Code tests vs. acceptance tests
Repeated but sequential integration
- Only one team at a time integrates code and releases the changes to the repository
- You don't end up chasing bugs
- However, you still end up integrate every couple of hours, so you don't fragment development
Pair programming
- One programs, the other one watches code
- Pairs and teams switch frequently
- Facilitates distribution of knowledge
Collective ownership
- You all own the code
- Everybody can check out and update code