Behavior Driven Development

Pravin D’silvaMCAGoa

University

AGENDA

Introduction TDD BDD Cucumber Gherkin Step Definitions Demo (Ruby) How to extend

INTRODUCTION

People have a lot of ideas in mind. The key to convert ideas to software:

COMMUNICATION Various stakeholders involved in completing

the task

WRONG PERCEPTION

TEST DRIVEN DEVELOPMENT

Automated Test Cases Produce minimum code to pass test Refactor code to acceptable standards

TDD

Advantages: Programmers tend to

be more productive Can drive the design

of a program Offers the ability to

take small steps Can lead to more

modularized, flexible, and extensible code

 Shortcomings Reliance on unit tests

might not perform sufficient full functional testing

Tests may share the same blind spots with the code

Tests become part of the maintenance overhead of a project

Rewrite the tests when requirements change

WHAT IS BDD?

“BDD builds upon TDD by formalizing the good habits of the best TDD practitioners.”

- Matt Wynne

 So what are those good habits? Working outside-in, starting from a business

or organizational goal Using examples to clarify requirements Developing and using a ubiquitous language

USE OF EXAMPLES Take care to write the acceptance tests as

examples that anyone on the team can read Get feedback from the business stakeholders Ensure the acceptance tests can easily be

read and written by anyone on the team Easier to validate Readable by computer

TRUE VALUE OF ACCEPTANCE TESTS communication collaboration tool

In BDDAcceptance Tests

areEXECUTABLE

SPECIFICATIONS

CUCUMBER TESTING STACK

Gherkin: 1. Specifications from plain-language text files called features.2. Each scenario is a list of steps for Cucumber to work through

Step Definitions:Map the business-readable language of each step into Ruby code to carry outwhatever action is being described by the step.

Automation library:One or two lines of Ruby that delegateto a library of support code, specific to the domain of your application.

CUCUMBER TESTING STACK

GHERKIN

Cucumber tests are expressed using a syntax called Gherkin.

Gherkin files: plain text and have a .feature extension

Use of Concrete Examples Lets take a scenario

Customers should be prevented from entering invalid credit card details.

PROBLEMSCustomers should be prevented from entering

invalid credit card details.

Ambiguity and Misunderstanding Lacks precision Worthy but vague

Lets take another scenarioIf a customer enters a credit card number that isn’t exactly 16 digits long, when they try to submit the form, it should be redisplayed with an error message advising them of the correct number of digits.

FEATURE Describe the features that a user will be able to enjoy when

using a programFeature: Feedback when entering invalid credit card details.In user testing we've seen a lot of people who made mistakes

entering their credit card. We need to be as helpful as possible here to avoid losing users at this crucial stage of the transaction.

Background: Given I have chosen some items to buy And I am about to enter my credit card details

Scenario: Credit card number too short When I enter a card number that's only 15 digits long And all the other details are correct And I submit the formThen the form should be redisplayed And I should see a

message advising me of the correct number of digits

SCENARIO

Each scenario is a single concrete example of how the system should behave in a particular situation

Scenarios all follow the same pattern: 1. Get the system into a particular state. 2. Poke it (or tickle it, or ...). 3. Examine the new state.

Start with a context, go on to describe an action, and then finally check

that the outcome was what we expected. Each scenario tells a little story describing something that the system should be able to do.

SUPPORT FOR VARIOUS LANGUAGES

Gherkin support in Hindi"native": "हिं��दी�","feature": "रूप लेख"    

"background": "प�ष्ठभू�मि�"

"scenario": "परि�दृश्य"  "scenario_outline": "परि�दृश्य रूप�ख�"  "examples": "उदी���ण"  

"given": "*|अग�|यदिदी|चूं��कि "  

"when": "*|जब“"then": "*|तब" "and": "*|औ�|तथा�"  "but": "*|प�"

Norwegian:Egenskap: SummeringFor å unngå at firmaet går konkursMå regnskapsførerere bruke en regnemaskin for å legge sammen tallScenario: to tallGitt at jeg har tastet inn 5Og at jeg har tastet inn 7Når jeg summererSå skal resultatet være 12

STEP LANGUAGES

Translates from plain language into Ruby

On the inside it tells your system what to do using Ruby automation code.

Ruby has an incredibly rich set of libraries for automating a whole variety of systems, from JavaScript-heavy web applications to REST web services.

FEATURE TO STEP DEFINITION

Feature:

Given I have $100 in my account

Regular Expression: /I have \$100 in my Account/

KEYWORDS

Feature Background Scenario Given When Then And But * Scenario Outline Examples

DEMO EXAMPLE

AFTER CREATING THE STEP DEFINITIONS FILE

The scenario has graduated from undefined to pending.

Given /^the input "([^"]*)"$/ do |input|

@input = input

end

When /^the calculator is run$/ do

@output = `ruby calc.rb #{@input}`

raise('Command failed!') unless $?.success?

end

Calc.rb is not found

After calc.rb is created (still blank)

print eval(ARGV[0]) in calc.rb

Then /^the output should be "([^"]*)"$/ do |expected_output|

@output=expected_output

end

ADDING ANOTHER SCENARIO

Scenario Outline: Add two numbersGiven the input "<input>"When the calculator is runThen the output should be "<output>"

Examples:| input | output || 2+2 | 4 || 98+1 | 99 |

ALL TESTS PASSED

ADDITIONAL USES OF CUCUMBER Databases Testing REST web services Capybara to Test Ajax Web Applications Aruba

USE CUCUMBER WITH JVM Install Maven Install m2e plugins for Eclipse Add Cucumber dependencies in pom.xml Run Maven builds and test using Cucumber

REFERENCEShttp://www.slideshare.net/tabaradetestare/tdt-bdd-gabi-kis?from_search=14

https://github.com/cucumber/cucumber-jvm

http://rspec.info/

http://c0deattack.wordpress.com/2012/03/28/cucumber-jvm-with-cucumber-java-cucumber-junit-example/

http://www.slideshare.net/ousam/cucumber-presenation