obs-tdd-intro

Amir Barylko - OBS Apr ‘11 MavenThought Inc.

AMIR BARYLKO

TDD INTRO

ONLINE BUSINESS SYSTEMSAPRIL 2011

Wednesday, April 27, 2011


WHO AM I?

•Quality Expert

• Architect

•Developer

•Mentor

• Great cook

• The one who’s entertaining you for the next hour!



RESOURCES

• Email: [email protected]

• Twitter : @abarylko

• Blog: http://www.orthocoders.com

•Materials: http://www.orthocoders.com/presentations


mailto:[email protected]


http://www.orthocoders.com/presentations



TDD TRAINING

•When: May 26 & 27

•More info: http://www.maventhought.com

• Goal: Learn TDD with real hands on examples


http://www.maventhought.com



INTROWhy projects fail?

Reality CheckNo more excuses

Why TDD?



WHY PROJECTS FAIL?

•Delivering late or over budget

•Delivering the wrong thing

•Unstable in production

•Costly to maintain



REALITY CHECK

• It is impossible to gather all the requirements at the beginning of a project.

•Whatever requirements you do gather are guaranteed to change.

•There will always be more to do than time and money will allow.



NO MORE EXCUSES

• It works on my computer!

• It was like that when I got here!

• The previous developer didn’t know XXXX!

• We need a satellite connection in order to run it!

• We can’t reproduce the error!

• We can’t test that!



WHY TDD?

•Prove that your code works

•Avoid waste (debugging)

• Increment code quality

•Better design

•Regression tests as byproduct

•Make changes with confidence

•Bring back the joy of coding!



APPLYING TDDIteration 0 .. N

Quality as a Driver Red - Green - Refactor



ITERATION 0

• Flush out architecture.

• Setup Testing harness for TDD and BDD.

• Setup continuous integration.

• Setup scripts to build, deploy, etc.

• Setup visual communication tools.



ITERATION 1.. N

• Start by Story Planning

• Pair programming (switching often)

•Daily Scrum

• End with Retrospective

Every day!



QUALITY AS A DRIVERRed

GreenRefactor

BDD

TDD

Red

GreenRefactor



RED

•Write a test that fails

•Relax, is ok if it compiles



GREEN

•Try to make the test pass

•Do a simple solution

•Use default values (not throwing exceptions)

•Don’t worry if the code “smells”



REFACTOR

•Avoid repeating code

•Avoid hardcoding dependencies

•Avoid “write only” code

•Refactor with confidence!

•Run all tests if possible



DEMOUnit Testing Frameworks

Given - When - ThenListing Contents

Reviews



TESTING FRAMEWORKS

•MsTest, xUnit, nUnit, MbUnit, MSpec

• Similar “hooks”

• Before and after test

• Before and after all test

• Arrange, Act, Assert



GIVEN WHEN THEN

• Test one “scenario” at a time

• Clear identification of functionality

• Easy to write, understand and maintain

• Repeatable, easy to learn



LISTING CONTENTS

• Controller “Movies” method “Index”

• Two scenarios

• Given I have no movies....

• Given I have the following movies....

•Where do I get the movies from?



GIVEN I HAVE NO MOVIES

[It]public void Should_not_return_any_movies(){ var result = (ViewResult)this.ActualResult;

var actual = (IEnumerable<IMovie>) result.ViewData.Model;

actual.Should().Be.Empty();}

[It]public void Should_render_the_index_view(){ this.ActualResult.AssertViewRendered();}



GIVEN I HAVE 10 MOVIES

[It]public void Should_return_all_the_movies(){ var result = (ViewResult)this.ActualResult;

var actual = (IEnumerable<IMovie>) result.ViewData.Model;

actual.Should().Have.SameValuesAs(this._movies);}



ARE WE DONE?

• Fail 1: IMovieLibrary is not registered in the container

• Fail 2: SimpleMovieLibrary needs the db name

• How can we make sure it works?

• Is TDD enough?



FIX THE CONTAINER

Component .For<IMovieLibrary>() .Instance(new SimpleMovieLibrary(dbFile))...



SUMMARYBenefits

ChallengesAdoption



BENEFITS

•Let the methodology drive

• It will save your bacon!

•High quality the whole way!

•Very few bugs!

•Do your duty as developer!



CHALLENGES

• Very different from conventional testing

• Many developers find it complex to learn at first

• Hard to start without a Mentor

• Management buy in

• Difficult to keep under deadline pressure

• Beware of code coverage!



ADOPTION

• Find Mentor/Couch/Trainer

• Small iterations

• Have metrics ready (velocity, etc)

• Do whatever works for you

• Find out which tools will benefit you

• Automate, automate, automate!


Amir Barylko - .NET UG Mar ‘11 MavenThought Inc.

QUESTIONS?



RESOURCES

• Email: [email protected]

• Twitter : @abarylko

• Slides: http://www.orthocoders.com/presentations







RESOURCES II



TDD TRAINING

•When: May 26 & 27

•More info: http://www.maventhought.com

• Goal: Learn TDD with real hands on examples




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