eXtreme Programming In Action Radoslav Nemchev Nemetschek OOD

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eXtreme Programming In ActionRadoslav
NemchevNemetschek OOD
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XP in action

• Choose the project
• Involve the customer
• Involve the team
• Apply the practices
• Automate

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Choose the project

• Not too big
• Not too small
• Not too important
• Not too unimportant

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Involve the Customer
How to make him work the XP way?
Who is the customer?
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Involve the team

• Guarantee them immunity
• Give them time
• Strictly control the practices application
• Let them see the benefits by themselves
• Provide communication stand-up meetings, open
  workspace,
• Shared understanding and responsibility for the
  system System Metaphor

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Apply the practices

• Introducing all practices at once, or just one
  practice at a time?
• Answer Adopt one practice at a time.
• What the order should be?
• Answer Follow the natural order from CR
  oriented through design to testing and coding.

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Customer on-site

• Customer or Developer on-site?
• Get the user stories
• Make him determine priorities high business
  value first
• Get him to give you immediate and frequent
  feedback
• Involve him into specification of functional
  acceptance tests

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Planning game

• How to plan?
• Create and prioritize user stories - customer
• Estimate difficulties - developers
• Select stories for next release - customer
• Split stories into tasks - developers
• Plan the tasks for the next iteration -
  customer/developers

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Small Releases

• My program is all or nothing! Wrong! Inside every
  large program there are lots of little programs
  trying to get out. Make them into small releases.
• Make as many iterations as possible per release
• Keep good track of progress
• Deliver business value to the customer fast
• Gives sense of accomplishment to the team
• Keep the team focused

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Test First

• Test-Driven development
• Design a test that will fail
• Compile it and check that it fails
• Write just enough code to make the test run
• Design evolves from tests
• The benefit must be higher than the cost
• Testing slows you down?
• Apply same quality standards for test and code
• Tests ARE documentation
• Automate

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Isolation Testing

• Collaborators of the unit under test are
• Trustworthy
• Implicit usage
• Object Mother Pattern
• Substituted in the test
• Stubs
• Self-shunt pattern
• Mock objects

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NUnit

• Unit tests framework
• Write tests
• Execute tests
• Assert results
• Show tests failure/success
• Keep the bar green
• http//nunit.org/default.htm

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NUnit test example
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Write test that will fail
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Write just the code that makes the test pass
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Refactoring

• Why refactor?
• Nobody does it quite right the first time
• To improve design
• To simplify code
• To ease future changes in the code
• When do we refactor?
• Continuously
• When code or test smells
• Automation

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C Refactory

• Integrated tool for Visual Studio
• Simplifies code refactoring
• Performs automatic code metrics collection
• http//www.xtreme-simplicity.net/

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Integration into MS Visual Studio
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Code metrics collection
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Refactoring with C Refactory
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Member reference finder
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Simple design

• How to achieve this?
• Evolutionary design design evolves while coding
  and refactoring
• If you dont need it now, you wont need it ever
  -develop only functionality that is required
• Satisfy tests in the simplest possible way
• Refactoring as soon as the tests run
• And again keep it as simple as possible!

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System Metaphor

• What?
• Everybody is involved, everybody is interested
• Everybody understands and is responsible for
• Base architecture
• Whole system
• How?
• Dont separate the team into designers and coders
• Change pairs often

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Pair programming

• Why?
• 2 gt 1
• Two programmers will understand the code
• Keeps programmers focused
• When do it?
• XP says always
• Is it possible in real life? Is it really
  necessary all the time?

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Continuous Integration

• You cant put it off forever. Better do it all
  the time
• Spare yourself the Big Bang disaster
• Keep the tests working 100 during the
  integration
• Use a dedicated integrated machine
• Keep the build time low
• Automate through scripts, tools, etc

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Collective Code Ownership

• This is not my object! WRONG!
• Use version control system CVS, VSS,
• You brake it, you fix it

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MS Visual Source Safe

• Automates Continuous Integration and Collective
  Code Ownership
• Provides version tracking
• Integrates with MS Visual Studio

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Coding Standards

• I can always read my own code. Wait, its all my
  code!
• Let the team setup coding standards prior to
  coding and agree on them
• Force coding standards application, no exceptions
• Keep it simple

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40 hour week

• Tired people make mistakes
• Tired people tend to overlook things like
  testing, refactoring, etc.
• Work at maximum concentration 8 hours per day
• 6 PM you are tired, go home
• Dont work more than 1 consecutive week of
  overtime