Behaviour Driven Development - Cuking the Agile world

www.unicomlearning.com

India Agile Week-2013
26-Oct-2013 at Pune

BDD in an Agile world
Gaurav Awasthi
Senior Architect and Technology Evangelist

www.agileinbusiness.com

Concept, Practice, Tools


Concept, Practice and finally Tools
Concepts are beyond Practices and Tools
Good Tools are better suited to Practices which
help internalize Concepts quickly

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The BDD World…
 Concepts
 Write software that matters
 In close collaboration with Stakeholder

 Practices
 Writing features, scenarios
 Write executable specs

 Tools
 Cucumber
 JBehave
 RSpecs
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BDD…by definition


BDD is a second-generation,
outside-in,
multiple-stakeholder,
high-automation,
agile methodology.
It describes a cycle of interactions with well-defined
outputs, resulting in the delivery of working, tested software
that matters.
Dan North
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Buzzword Agnostic Benefits…


• Seamless mapping between Requirement statements and
executable tests

• Specification by example
• Loose grammar of the domain
• Brings Testers/QA to the forefront of development
process
• Self verifying documentation

• Evolves behavior as the domain understanding changes
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Co-existence with TDD
Write a failing
feature test

BDD


Write a
failing unit
test
TDD

Refactor
TDD – Develop it the
right way
BDD – Develop the right
thing
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Make the
test pass

And what about DDD ?
• Domain Driven Design
• Ubiquitous Language
• gives vocabulary
• Inside Out

• Behavior Driven Development
• Sentences out of the vocabulary
• Description of the behavior
• Outside In

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The BDD Practice


1. Describe the behavior in plain text – Features and Scenarios
2. Write a step definition for each Step
3. Run it and watch it fail
4. Write code to make the step pass
5. Run it again and see the step pass
6. Repeat step 2 – 5 until green like a Cuke
7. Repeat step 1 – 6 until the money runs out

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The Tool - Cucumber
Why Cucumber ?
• one of the least technical tools
• a very active open source project
• supports a variety of languages

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Slicing Cucumber


•

JBehave -> ported to Ruby -> RBehave -> rewritten from scratch > RSpec -> + story runner -> Cucumber -> Cucumber-JVM

•

Aslak Hellesoy ported Cucumber to Java (cucumber-jvm)

•

Cucumber comes with Ruby (the original), Java, .NET, Adobe Flex,
Python, Perl, Erlang, PHP

•

Full stack for acceptance tests include – Browser Driver and
Browser

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Gherkin


• A Business Readable, Domain Specific Language that
Cucumber understands
• Line-based language that Cucumber uses to define
behaviors in the form of features, scenarios, and steps

• Serves 3 purposes :
•
•
•

Automated Tests
Documentation
Specs for Code to be written

• Source files have .feature extension. Single Gherkin source
file contains a description of a single feature
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Gherkin syntax
Feature : title


 As a [ person or role who will benefit ]
 I want [ some feature ]
 So that [ benefit or value of the feature ]
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Gherkin syntax
Scenario : title
 Given [ some initial context ]
 When [ an event occurs]
 Then [ ensures some outcome ]
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Example
Feature: Customer
purchases a device
• As a Customer
• I want to purchase a Bluetooth
device
• So that I can make or receive a
hands free call


Scenario : Customer has a
credit note valued more
than the receipt amount
• Given the customer is on the till

• And he has a credit note of Rs
1000
• And the receipt amount is Rs 500
• When the balance amount is
paid
• Then the billing completes

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Cucumber Options
@RunWith(Cucumber.class)
@Cucumber.Options (
tags = “@focus”,
features= “classpath:billing.feature”
)
public class CukeRunner {
}
Some common options :
• features – path to the feature files
• glue – where to look for step definition and hooks
• tags – what tags in the features should be executed
• format – what formatters to use
• …
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CLI Option


• Several Runners
•
•
•

Command Line Interface
JUnit Runner
Android Runner

cucumber-core
cucumber-junit
cucumber-android

• java cucumber.cli.Main [options] [FILE|DIR]
•

--glue , --format, --tags, --name …

• Benefit :
•
•

Independent of JUnit
Integration with Ant

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Demo Code
•

Create a maven project, with cucumber-jvm related
dependencies
•

•

Feature: Withdrawing money from a User account
•
Scenario: Withdrawing money from a User's account should
reduce money in the current balance
•
Given a User has $100 in his account
•
When $50 is withdrawn from the account
•
Then the balance should be $50

Write Java wrapper class – like CukeRunner,
•

•
•
•

cucumber-core, cucumber-java, cucumber-junit

Write a Feature and a scenario with steps
•

•


annotated with RunWith and Cucumber.Options

Run the class, let it fail
Implement Steps, Run again
See it green like a cuke

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And the debate


To TDD, To BDD
or
To prefer one over the other

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References
•
•
•
•
•


That's not BDD, that's just Cucumber by Chris Parsons
Introducing BDD by Dan North
http://dannorth.net/whats-in-a-story/ by Dan North
http://cukes.info/install-cucumber-jvm.html
http://cukes.info/api/cucumber/jvm/javadoc/cucumber/api/junit/C
ucumber.Options.html

UNICOM Presents



Speaker name: Gaurav Awasthi
Email ID: gawasthi22@gmail.com

Organized by
UNICOM Trainings & Seminars Pvt. Ltd.
contact@unicomlearning.com

Behaviour Driven Development - Cuking the Agile world

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