xTreme Programming by Sejo Ćesić and Enis Zeherović

eXtreme Programming
Sejo Ćesić
sejo@agile.ba
be.linkedin.com/in/sejocesic/
Enis Zeherović
enis@agile.ba
ba.linkedin.com/in/eniszeherovic

eXtreme Programming
 Formulated in 1999 by Kent Beck, Ward
Cunningham and Ron Jeffries
 AGILE software development
methodology
 Developed in reaction to high ceremony
methodologies (e.g. Rational Unified
Process - RUP)

XP Goal
Organize people
to produce
higher-quality software
more productively

XP Activities
 Coding
 Testing
 Listening
 Designing

XP Values
 Communication
 Simplicity (YAGNI)
 Feedback
"Optimism is an occupational hazard of programming.
Feedback is the treatment.“
 Courage
refactor/remove code, be persistent
 Respect

XP Practices
1. Pair programming
2. Planning game
3. Test driven development
4. Whole team - customer is in the team
5. Continuous process (integration, refactoring,
small releases)
6. Shared understanding (coding, collective
ownership, simple design)
7. Sustainable pace

Pair programming
Driver & Navigator metaphor improving:
- Economics
Errors avoided, zero cost to fix them later
- Design quality
Second opinion constantly questioning yours
- Satisfaction - Great confidence in code
- Learning - Constant exchange of knowledge
- Team building - Communication improves
exponentially

Resistance to XP
 2 programmers cost 2 times more than 1
programmer!
 Place full of people never shutting their mouth
will drive you insane!
 When do I get to surf the web? Or chat online?

Resistance to XP (cont.)
 Mistakes of a single person cost much much
more!
 Once you are working with your pair, you don't
hear anyone else anymore.
In fact, smart manager knows:
No noise -> something is wrong!

Planning game
 Release plan
 Iteration plan
 Acceptance test
 Stand Up Meeting
 Pair Negotiation
 Unit Test
 Pair Programming

Burndown and velocity
 How much work is getting done on your project?
 Burndown keeps track of iteration progres
 Calculate velocity on the end of iteration
=(estimated hours - remaining hours) / nr. of
days

Test driven development
… will be presented soon

Whole team
Customer is “on site” and used for:
 writing user stories
 release and iteration planning
 complete programming tasks
 functional testing
Alternative: “proxy customer”

Continuous process
 Continuous integration
 Design improvement, refactorings
 Small releases, shippable products,
demonstration per iteration

Shared understanding
 Coding standard
 Collective code ownership
 Simple design
 System metaphor

Sustainable pace
 Frequent code merge
&
always executable
&
test covered high quality code
---> fresh and alert minds
 40 hours week

 Add a test
 Run all tests and see if the new one fails
 Write some code
 Run tests
 Refactor code
 Repeat

Apply F.I.R.S.T. properties of unit tests:
Fast
many hundreds or thousands per second
Isolates
failure reason become obvious
Repeatable
run repeatedly in any order any time
Self-validating
no manual evaluation required
Timely
written before the code

 One assert per test
 Descriptive names of tests
 Test code is important as production code
(maybe more)
 Recognize test code as documentation you are
always missing
 The quality of a test is how good it points you
on the failure in your system if it fails

TDD - practical introduction
Two parts:
 Java TDD Kata in Eclipse
 User interface TDD testing

TDD Kata
 String Calculator:
 Set of requirements
 Develop one task at a time
 Test only positive cases

TDD Kata – String Calculator
 Requirements:
1. Empty string returns zero
2. String with single digit returns that digit
3. String with 2 digits separated with a ‘,‘
retuns sum of these 2 numbers ()
4. Unknown number of digits separated by ‘,‘
must be possible
5. A new line can be used as a separator
6. Custom delimiter must be supported
(//[delimiter]n[numbers])

User interface TDD testing
 New page development in TDD
 Tools: Eclipse, Selenium, TestNG
 Free tool: testeditor.org

xTreme Programming by Sejo Ćesić and Enis Zeherović

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