obs-tdd-intro

AMIR BARYLKO
TDD
INTRO

ONLINE BUSINESS SYSTEMS
APRIL 2011

Amir Barylko - OBS Apr ‘11 MavenThought Inc.
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: amir@barylko.com

• Twitter: @abarylko

• Blog: http://www.orthocoders.com

• Materials: 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


INTRO
Why projects fail?
Reality Check
No 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! • We need a satellite
connection in order to
• It was like that when I got run it!
here!
• We can’t reproduce the
• The previous developer error!
didn’t know XXXX!
• We can’t test that!


WHY TDD?

• Prove that your code • Regression tests as
works byproduct
• Avoid waste • Makechanges with
(debugging) conﬁdence
• Increment code quality • Bring
back the joy of
coding!
• Better design

APPLYING TDD
Iteration 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) Every day!

• Daily Scrum

• End with Retrospective


QUALITY AS A DRIVER
Red
BDD

Red

Refactor Refactor TDD Green Green


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

DEMO
Unit Testing Frameworks
Given - When - Then
Listing 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))...


SUMMARY
Beneﬁts
Challenges
Adoption


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!

QUESTIONS?

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

RESOURCES

• Email: amir@barylko.com

• Twitter: @abarylko

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


RESOURCES II


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