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Agenda
• What is Test-Driven Development?
• How to do TDD
• TDD and Visual Studio 2005
• What now?
• More Information
• Q&A
What is TDD?
“Test-Driven Development seeks specification, not validation, letting you think through your design before you write your functional code”
- Scott Ambler
“Test-Driven Development is a powerful way to produce well designed code with fewer defects”
- Martin Fowler
What is TDD?
• ‘History’:– The inner loop of Extreme Programming
• TDD is:– A design method (and more)
• TDD is not:– Just writing tests first– A guarantee of quality– Unit testing
What is TDD?
• TDD as a Design Method:– Evolutional– Baby steps– Iterative
What is TDD?
• Evolutional:– No Analysis and Design first– Resilience when requirements are discovered
or change
What is TDD?
• Baby Steps:– One test at the time– Avoid complex code– Code quickly
• Fix the current test
– The majority of invested time should be spend on refactoring
What is TDD?
• Iterative
Update test list
Pick a test
Write the test
Get the code to compile and FAIL
See the test fail
Make the code pass the test
Refactor
Run all tests
How to do TDD
• Updating the Test List– Add small portions of functionality– Add extra test cases– Do not try to make the list complete from the
start– Prioritize the tests
• Risk, ability, …
– Do this during the entire process• Do NOT get sidetracked!
How to do TDD
• Pick a Test– Pick the single test on top of the test list
How to do TDD
• Write the Test– Keep the code as clean as possible– Update the test list instead of coding extra
tests
DEMODEMO DEMODEMO
How to do TDD
• Get the Code to Compile and FAIL– Add a method stub that throws an exception
• NotImplementedException
DEMODEMO DEMODEMO
How to do TDD
• See the Test Fail– You want to be sure it fails: Test the test…
DEMODEMO DEMODEMO
How to do TDD
• Make the Code Pass the Test– Don’t worry too much about ‘clean’ code
• Get the work done
• Do NOT add code that is not being tested
• Do NOT use too many stubs/mockups
DEMODEMO DEMODEMO
How to do TDD
• Refactor– Cleaning up– Remodeling without changing external
behavior• This is where the Unit Tests prove their use
– Allows easy addition of new code – Breaking down large methods/classes– Removing duplicates– Reordering code DEMODEMO DEMODEMO
How to do TDD
• Run All Tests– Making sure you didn’t break the solution– Theoretically: Always run all tests
• This might take to long always run all tests when making a daily build
DEMODEMO DEMODEMO
TDD and Visual Studio 2005
• From the Demo:– Unit Testing
• Generating stubs• Generating tests• Debugging
– Coverage checking– Refactoring
TDD and Visual Studio 2005
• Visual Studio Also Allows:– ‘GUI’ testing– Load testing (Web Applications)– Performance monitoring
• Team System Allows to:– keep track of work items– keep track of progress– force the tests to run successfully before
enabling to check-in the code
TDD and Visual Studio 2005
• Visual Studio 2005 Delivers the Tools– It does NOT force you to use them– They can be used in ANY kind of software
development process (MSF, RUP, XP, …)
What now?
• Developers:– Learn to Refactor– Learn Unit Testing– Learn Whidbey
• Technical Project Leaders:– Learn/adopt a Software Development Method– Learn Visual Studio Team System/Foundation
Server
More Information
• http://www.infosupport.com
• http://msdn.microsoft.com
• http://www.testdriven.com
• “Refactoring: Improving the Design of Existing Code” - Martin Fowler
More Information
• MSDN Fast Track– http://www.microsoft.nl/msdnfasttrack– Technical Seminars (1 day) &
Technical Training (3-5 days)• SQL Server Database Development• Visual Studio Team System• SQL Server Business Intelligence• Smart Client Development• Web Development
Q&A
