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C# TDD Painkillers@Ben_HallBen@BenHall.me.ukBlog.BenHall.me.ukCodeBetter.com/blogs/BenHall

WH

O AM

I?London based ASP.net MVPWeb Developer @ 7digital.com

Open Source Developer

Co-Author Testing ASP.net Web Applicationswww.testingaspnet.com

YouTest Design App Design

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Test Design

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TDD doesn’t mean NUnit

TDD is about learning

TDD is about validating the unknowns

Proving your own assumptions

Fundamentally the biggest TDD painkiller is not doing TDD

That’s why we have a QA department

Developer writing the testDeveloper writing the implementation

Do the simplest thing possible.

“First make it work, then make it right”

“TDD like you meant it”

Spike

http://www.flickr.com/photos/peasap/1625639532/sizes/l/

IRB (Ruby)

http://github.com/BenHall/CastleDynamicProxy101/blob/master/CastleDynamicProxy101/Program.cs

http://github.com/BenHall/memcached101/blob/master/MemcacheDemo/Program.cs

NUnit makes learning repeatable

Helps guide the learning during implementation

TEST NAMING AND STRUCTUREPain killer

Structure

EXAMPLE

EXAMPLE

Context \ Spec

Naming of test Implementation

ACTUAL TEST IMPLEMENTATIONPainkiller

Highlight relevant data

Duplicated Setup in testEXAMPLE

Duplicated Setup in testEXAMPLE

Tests are documentation

IT DEPENDS

Given, When, Then

Scenario: Payment method has expired Given user John And John has expired credit card When I get the default payment method Then an invalid credit card will be returned

Cuke4nuke \ SpecFlow

DESIGN SMELLS INDICATE IT’S NOT DONE VIA TDD

Random, Dates, Machine Settings• DateTime.Now();• new Random().Next();

Use static Func<T>

http://www.flickr.com/photos/gagilas/2659695352/

EXTERNAL DEPENDENCIES

Fake the other side

Mock External Dependencies

Anti Corruption

http://www.flickr.com/photos/aresauburnphotos/2678453389/sizes/l/

Mock Usage

http://ayende.com/Blog/archive/2006/07/02/DoNOTMockSystemData.aspx

Fragile to refactoring

Running away from HttpContext

Interfaces establish behaviour boundaries.

Stub\Mock at boundaries

Let the tests drive the design

Application Design

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Dependencies

Poor man’s IoC

REALLY?!?

Design SmellSmell - Responsibilities

http://www.flickr.com/photos/ricmcarthur/56268640/

Tests help indicate smells

Tests help indicate smells

Abstract away?

Combined service?

• Single responsibility principle• Open/closed principle• Liskov substitution principle• Interface segregation principle• Dependency inversion principle

UI Testinghttp://blig.ig.com.br/brokenarrow/files/2009/04/too_many_toolbars.jpg

WPF Apps With The Model-View-ViewModel Design Pattern

MVVM Pattern

http://msdn.microsoft.com/en-us/magazine/dd419663.aspx

MVP Pattern

MVP Pattern

Acceptance Test Driven Development

http://codebetter.com/blogs/benhall/archive/2010/03/16/testing-a-wpf-ui-using-ruby-cucumber-and-wipflash-dll.aspx

Scenario: Saving a product by name only Given the application has started And I enter the name "Product 1" When I save the product Then "Product 1" should be available to purchase

Given /^the application has started$/ do host = ApplicationLauncher.new @app = host.launch Dir.pwd + '/src/ExampleUIs/bin/Debug/ExampleUIs.exe' @main_window = @app.find_window 'petShopWindow' end Given /^I enter the name "([^\"]*)"$/ do |product_name| textbox = @main_window.find_TextBox "petNameInput" textbox.text = product_name end When /^I save the product$/ do button = @main_window.find_Button "petSaveButton" button.click sleep(1) end Then /^"([^\"]*)" should be available to purchase$/ do |product_name| combo = @main_window.find_ComboBox "basketInput" combo.Items.should include("Pet[#{product_name}]") end After do |scenario| @app.process.kill end

Full stack testing for ATDD?

WHAT’S GOOD APPLICATION DESIGN?

Code Coverage

Code and Test Reviews

7digital XTCR – Cross Team Code Review

It’s all about the mindset

Hardest part == getting started

Second hardest part == keep doing it

Becomes natural

Pair with someone

http://www.flickr.com/photos/jasohill/65804069/sizes/l/

Kata

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Fear

http://www.flickr.com/photos/bartt/34937855/

http://www.flickr.com/photos/leon_homan/2856628778/

End of the line

Summary• Let the tests drive your design• Listen for smells• Fear – beat the lizard brain• just do it!

@Ben_HallBen@BenHall.me.ukBlog.BenHall.me.uk

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