Behavior Driven Development

Behavior Driven Development
Vermont
Code Camp
September 11, 2010
By Tom Cooley

Tom Cooley
Principal Software Architect at MyWebGrocer
Developer for 20+ years
C# for 7+ years
Primary focus includes:
Object-oriented architecture
Design patterns and principles
Database development/DBA for 14+ years
Co-leader of VT SQL Server user group
Member of International Association of Software Architects
Presenter at VT .NET and VT SQL Server user groups

Session Overview
Why is testing so hard?
BDD Overview
The Ubiquitous Language of BDD
The BDD Story
Specifications
Tools and toys
and of course…demo code

Unit Testing
The good, the bad, the ugly

Evolution of TDD Learning and Adoption
The developer starts writing unit tests around their code using a test framework like JUnit or NUnit.
As the body of tests increases the developer begins to enjoy a strongly increased sense of confidence in their work.
At some point the developer has the insight (or is shown) that writing the tests before writing the code, helps them to focus on writing only the code that they need.
The developer also notices that when they return to some code that they haven't seen for a while, the tests serve to document how the code works.
A point of revelation occurs when the developer realizes that writing tests in this way helps them to “discover” the API to their code. TDD has now become a design process.
Expertise in TDD begins to dawn at the point where the developer realizes that TDD is about defining behavior rather than testing.
Behavior is about the interactions between components of the system and so the use of mocking is fundamental to advanced TDD.
Source: http://behaviour-driven.org/Introduction

Story Time
Once upon a time…

BDD Story Semantics
As a <role>
I want <some feature>
So that <business value>
As a speaker
I want to be able to select a preferred time of day to present
So that I can accommodate my travel plans to attend Code Camp

User Acceptance Tests
Scenarios
Given <pre-condition>
And<another pre-condition>
When <behavior is performed>
Then <outcome>
And <another outcome>

Scenario 1: Presentation is scheduled according to preferred time of day
Given a speaker with an early morning preference
And the schedule has an open time slot that matches the preference
When the coordinator schedules the session using the speakers preference
Then the session is successfully scheduled
And the number of open time slots in the schedule is one fewer
Scenario 2: Presentation is scheduled into time slot that does not match the speaker’s preference
Given a speaker with an early morning preference
And a matching time slot is available
When the coordinator assigns the session to an afternoon time slot
Then the session is not scheduled
And the number of open time slots should not change
And a warning occurs indicating the conflict
Scenario 3: All time slots matching speaker’s preference are taken
Given a speaker with a morning preference
And a matching time slot is available
When the coordinator assigns the session to begin in the morning
Then the session is scheduled
And the number of open time slots in the schedule is one fewer

Context-Specification Style
[Context]
When scheduling a session using a speaker’s preference
[Specification]
should assign to earliest time slot that matches speaker preference
[Specification]
Should assign earliest available time slot when no others match speakers preference

Tools & Toys
StoryQ – a library that uses Domain Specific Language (DSL) of Behavior Driven Development
NBehave – similar library. I use for extension methods to assert outcomes
AutoHotKey - Automate almost anything by sending keystrokes and mouse clicks. You can write a macro by hand or use the macro recorder.

Resources
Email me at: tom@cooley.name
http://dannorth.net/introducing-bdd
http://behaviour-driven.org/
http://storyq.codeplex.com/
http://nbehave.codeplex.com/
http://www.autohotkey.com/
http://blog.jpboodhoo.com/BDDAutoHotKeyScriptUpdateTake1.aspx
http://blog.jpboodhoo.com/BDDAutoHotKeyScriptUpdateTake2.aspx

Behavior Driven Development

by TomCooley on Sep 13, 2010

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Behavior Driven Development — Presentation Transcript