bdd behaviour driven development
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This document provides an introduction and overview of Behavior Driven Development (BDD). It discusses how BDD evolved from test-driven development (TDD) and acceptance test-driven planning. BDD integrates TDD and domain-driven design into a unified approach. The document outlines the origins of BDD from the work of Dan North and describes templates for writing user stories and scenarios in BDD. Examples are provided to illustrate BDD in practice. Key principles of BDD are defined, and it is distinguished from TDD by focusing on specifying overall system behavior from the business perspective rather than testing components in isolation. References for further reading on BDD are also included.
![Template for user stories
As a [X]
I want [Y]
so that [Z]
in ubiquitous language!
As a customer,
I want to withdraw cash from an ATM,
so that I don’t have to wait in line at the bank.
A story’s behaviour is simply its acceptance criteria – if the system fulfills all the acceptance
criteria, it’s behaving correctly; if it doesn’t, it isn’t. So we created a template to capture a
story’s acceptance criteria.
Source: http://dannorth.net/introducing-bdd/
© 2010 Capgemini – All rights reserved
#16_BDD – Behaviour Driven Development.pptx
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bdd behaviour driven development
- 1. BDD – Behaviour Driven Development Marek Majchrzak, Andrzej Bednarz Wrocław, 11.10.2011
- 2. BDD in a nutshell It is an evolution in the thinking behind TDD (Test Driven Development) and Acceptance Tests Driven Planning It brings together strands from TDD (Test Driven Development) and Domain Driven Design into an integrated whole Source: http://behaviour-driven.org/ Source: http://lostechies.com/derekgreer/2011/03/21/effectivetests-test-first/ © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 2
- 3. BDD origins – Dan North I had a problem. While using and teaching agile practices like test-driven development (TDD) on projects in different environments, I kept coming across the same confusion and misunderstandings Programmers wanted to know where to start, what to test and what not to test, how much to test in one go, what to call their tests, and how to understand why a test fails. My response is behaviour-driven development (BDD). Source: http://dannorth.net/introducing-bdd/ © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 3
- 4. Template for user stories As a [X] I want [Y] so that [Z] in ubiquitous language! As a customer, I want to withdraw cash from an ATM, so that I don’t have to wait in line at the bank. A story’s behaviour is simply its acceptance criteria – if the system fulfills all the acceptance criteria, it’s behaving correctly; if it doesn’t, it isn’t. So we created a template to capture a story’s acceptance criteria. Source: http://dannorth.net/introducing-bdd/ © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 4
- 5. Template for scenarios Given some initial context (the givens), When an event occurs, Then ensure some outcomes. Scenario 1: Account is in credit Scenario 2: Account is overdrawn past the overdraft limit Given the account is in credit And the card is valid And the dispenser contains cash When the customer requests cash Then ensure the account is debited And ensure cash is dispensed And ensure the card is returned Given the account is overdrawn And the card is valid When the customer requests cash Then ensure a rejection message is displayed And ensure cash is not dispensed And ensure the card is returned Source: http://dannorth.net/introducing-bdd/ © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 5
- 6. Example © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 6
- 7. Example © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 7
- 8. Example © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 8
- 9. Example © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 9
- 10. Example © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 10
- 11. Another example Given a stock of <symbol> and a <threshold> When the stock is traded at <price> Then the alert status should be <status> Examples: |symbol|threshold|price|status| |STK1|10.0|5.0|OFF| |STK1|10.0|11.0|ON| © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 11
- 12. The Core Principles Business and Technology should refer to the same system in the same way – Its all behaviour Any system should have an identified, verifiable value to the business – Wheres the business value Up-front analysis, design and planning all have a diminishing return – Enough is enough © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 12
- 13. BDD vs TDD • It is important to keep BDD distinct from TDD. These two practices are equally important but address different concerns and should be complementary in best development practices. • BDD is concerned primarily with the specification of the behavior of the system under test as a whole, thus is particularly suited for acceptance and regression testing. TDD is concerned primarily with the testing of a component as a unit, in isolation from other dependencies, which are typically mocked or stubbed. • BDD should talk the language of the business domain and not the language of the development technology, which on the other hand is “spoken” by TDD. © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 13
- 14. Sources, References and more… 1. Dan North, Introducing BDD, http://dannorth.net/introducing-bdd/ 2. BDD Wiki, http://behaviour-driven.org/ 3. JBehave, http://jbehave.org/ 4. RSpec, http://rspec.info/ 5. Cucumber, http://cukes.info/ 6. Dan North, Deliberate Discovery, http://dannorth.net/2010/08/30/introducing-deliberatediscovery/ 7. Dan North, Programming is not a craft, http://dannorth.net/2011/01/11/programming-is-not-a-craft/ & Martin Fowler http://martinfowler.com/bliki/CraftmanshipAndTheCrevasse .html 8. Liz Keogh's blog, http://lizkeogh.com/ © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 14
- 15. Vielen Dank für Ihre Aufmerksamkeit! www.de.capgemini.com
- 16. Programming is not a craft - Opposition to Software Craftmanship The software shouldn't be at the center of a programmer's world, instead a programmer should focus on the benefit that the software is supposed to deliver. Martin Fowler I would love to see someone rewrite the Software Craftsmanship Manifesto in terms of getting results and delighting customers. Dan North I don’t want “steadily adding value,” I want “amazing their customers every day!” Software craftsmen should be egoless, humble, with a focus on the outcome rather than the code or the process. Dan North … refactoring to oblivion while failing to deliver, focusing on test coverage while the company continues to leak money, worrying about the latest testing tool while failing to talk to stakeholders, or insisting that no one can interrupt their two-week sprint once they’ve made a commitment … Liz Keogh © 2010 Capgemini – All rights reserved #16_BDD – Behaviour Driven Development.pptx 16