Behavior Driven Development in the Real World - PowerPoint PPT Presentation

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SESSION CODE: DPR302

Behavior Driven Development in the Real World

David Starr

Pluralsight Instructor

ALM Consultant

Visual Studio ALM MVP

starr@pluralsight.com

Blog: ElegantCode.com

@elegantcoder

• Conversations About Software
• Expressing Desirements Well
• Making Requirements from Desirements
• Specification in Context
• BDD Tools

• So we use specifications
• Use Cases
• UML diagrams and models
• Numerous large document models
• Specification and Requirements
• Can be expensive to produce
• Good enough often preferred to perfect
• Must evolve easily as the software does

This isn’t what I thought

we agreed on.

• Users think at this level
• Software has behavior at this level
• UI elements give us something to discuss

Paper

Whiteboards

Visio

PowerPoint

SketchFlow

• User Stories represent needed conversations

As a <application role>

I want <some feature or behavior>

So that <I get some benefit>

• Scenarios document the conversation took place

Given <some initial context>

When <this happens>

Then <this should be the result>

Desirements are things we wish the software did.

But it doesn’t. Yet.

Story: Remove Item From Shopping Cart

As aCustomer with Products in my Cart I wantto remove an ItemSo I canchange my mind about buying it

Scenario: Multiple Items in CartGiven a Cart with multiple Items in itWhen 1 Item is removedThen the other Items are still in the Cart

And the Cart Item Count is correct

And the Cart Subtotal reflects the remaining Items

Customer

Domain Concepts

UI Element Behavior

Input Validation

Services

Class Behavior

Repositories

Developer

• Executable Specifications

Expressing requirements such that they are also tests

Because Microsoft Word documents can’t prove software works

• Sweet Aromas of Executable Specifications
• Meaningful to all interested parties
• Unambiguously demonstrate if the requirement is met
• Drive out a testable design
• Simple

As a

I want

So that

As a

I want

So that

• Make tests that read as Desirements
• Tests fail against the SUT
• Tests pass against the SUT
• Discuss results with customer
• Add more and refine as conversations occur

Given

When

Then

Given

When

Then

Given

When

Then

Given

When

Then

Given

When

Then

Given

When

Then

[TestMethod]

public void

Total_Should_Be_1_When_1_Product_Added()

{

var cart = new ShoppingCart("TEST");

cart.AddItem(new Product("SKU"));

Assert.AreEqual(1, cart.TotalItems);

}

User Story

Structure

AAA

Context

Specification

• Keeps our tests DRY
• Reuse existing classes

• Keeps our tests DRY
• Can be fragile
• Watch Depth of Inheritance

• Popular Context / Specification library
• Love it or hate it
• Less to type than rolling your own
• May replace existing your existing unit test framework
• Includes report generator
• Get it here: http://link.pluralsight.com/39um

= () =>

• Get started with BDD quickly
• Too prescriptive for some
• Fluent interface for ease-of-use
• Compatible with MSTest / NUnit / XUnit
• Get it here: http://link.pluralsight.com/3jaf

• StorEvil – Another good .NET BDD libraryhttp://link.pluralsight.com/4n4z
• SpecFlow – Another good .NET BDD libraryhttp://link.pluralsight.com/3uwd
• Cucumber – BDD for Ruby and IronRubyhttp://link.pluralsight.com/56j7
• Gherkin – A DSL for BDDhttp://link.pluralsight.com/46nm
• StoryTeller- .NET native alternative to Fitnessehttp://link.pluralsight.com/5vdn

• Better understand each other before getting started
• Ideas of Functionality are Desirements
• Desirements express well as User Stories
• BDD helps turn Desirements into Requirements
• There are many supporting tools to help

starr@pluralsight.com

Blog: ElegantCode.com

@elegantcoder

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Learning

• Sessions On-Demand & Community

• Microsoft Certification & Training Resources

www.microsoft.com/teched

www.microsoft.com/learning

• Resources for IT Professionals

• Resources for Developers

• http://microsoft.com/technet

• http://microsoft.com/msdn

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