Introduction to Acceptance Test Driven Development

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In The Seven Habits of Highly Effective People, Stephen R. Covey names "Begin with the End in Mind" as the second of the seven habits. This habit applies not just to individuals, but to software development teams as well. In Acceptance Test Driven Development (ATDD), the Product Owner begins requirements discussions with expectations and examples, and the whole team collaborates to distill these into acceptance tests that define the essence of “Done." Modern testing frameworks enable the team to express the tests in natural language while connecting them to the software so that the tests are automated while the software is being developed. The end result is that the acceptance tests become executable requirements.

These slides explain the ATDD cycle and how it fits with other Agile development and testing practices including TDD, Continuous Integration, and Exploratory Testing.

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Introduction to Acceptance Test Driven Development

  1. 1. Beginning with the End in Mind: Driving Development with Acceptance Tests Elisabeth Hendrickson Quality Tree Software, Inc. www.qualitytree.com esh@qualitytree.com Last updated November 10, 2009 This work is licensed under the Creative Commons Attribution 3.0 United States License. View a copy of this license.
  2. 2. What is ATDD?
  3. 3. Acceptance-Test Driven Development (ATDD) Cycle 0&1(/.2 3,.4#15 -21&6 -21&6 -21&6 -21&6 -21&6 0&1(/.2 !$-./-- '" ( * + #" , ) &" " * !"#$%"& !"%"#17
  4. 4. ATDD: Discuss !"#$%&' ()&*+#, !"#$%& '(&%$)*#(&+(, -'#". -'#". -'#". -'#". Concrete Examples with -'#". Expectations
  5. 5. ATDD: Develop '*&+%","-."/,/ '()*+"& %#$& !"# ,-(* .&/*/ !"#$ & ' (" ) $ %" " %#$& &
  6. 6. ATDD: Deliver Product Feature Feature Feature Feature Feature Feature FeatureFeature Feature
  7. 7. Introducing an Example
  8. 8. Start with the Story As an administrator, I want users creating accounts to be required to choose secure passwords so that their accounts cannot be hacked by someone using a password guessing program.
  9. 9. Discuss And if a user provides Who’s in the an insecure password, room? display an error Product message. Owner, Testers, Developers, and anyone else who will touch the What does story. “secure” mean to you? At least 6 characters with at least one letter, one symbol, and one number.
  10. 10. Capture Concrete Expectations and Examples Password Valid? Can be expressed as “p@ssw0rd” Yes “Given - When - “p@s5” No Then” “passw0rd” No Given a user is creating an account “p@ssword” No When they specify an insecure “@#$%1234” No password Or can be Then they see a message, expressed in tables “Passwords must be at least 6 characters long with at least one Or in other formats letter, one number, and one depending on the symbol.” Framework
  11. 11. Why ATDD? Reason #1: Drive Out Ambiguity and Clarify Expectations
  12. 12. This is not an Argument about a Bug “Bug Triage Meeting” The Tuesday before release. It’s a bug. No it’s not. Whether or not it’s a bug, if we Is too. make a change we’ll blow the IS NOT. schedule. IS TOO! NOT NOT NOT!
  13. 13. Acceptance Tests Define Scope
  14. 14. A Short Digression on ATDD-Friendly Tools
  15. 15. Examples of ATDD-Friendly Frameworks • Cucumber: a Ruby-based BDD tool that supports “Given-When-Then” • Fitnesse: a table-driven framework that uses a wiki for displaying and editing tests • Robot Framework: keyword-driven framework that supports text or tables • Concordion: Java-based framework for expressing expectations in prose
  16. 16. Frameworks, Interfaces, and Drivers Created in Code written during collaboration. development in a GUI Driver Format defined programming language (e.g. SeleniumRC) by the determined by the framework framework. GUI Public API Test Natural “Guts” “Fixture” Language Expectations Other interfaces Implementation
  17. 17. Characteristics of ATDD-Friendly Frameworks •  Support expressing expectations in a language and format that fits the context •  Support collaboration among the whole team including developers, testers, & the product owner •  Connect expectations to the system under test with a minimum of test code (“fixtures,” “libraries,” “steps”) to leverage expectations as executable requirements •  Play nicely with source control systems and continuous integration •  Pluggable to support a variety of interfaces
  18. 18. Contrasting View: Traditional Test Automation GUI Automated Test Scripts: Public API Combination of “Guts” business-facing expectations and Other implementation interfaces details. Implementation Written or recorded after the fact. Expectations are translated, not leveraged.
  19. 19. Back to the Example…
  20. 20. Take the Acceptance Tests… Password Valid? “p@ssw0rd” Yes “p@s5” No “passw0rd” No Given a user is creating an account “p@ssword” No When they specify an insecure “@#$%1234” No password (Note that these Then they see a message, expectations are “Passwords must be at least 6 implementation-agnostic characters long with at least one and express just the letter, one number, and one essence of the symbol.” expectation.)
  21. 21. …and Write the Code Password Valid? Test GUI “p@ssw0rd” Yes “Fixture” “p@s5” No Public API “passw0rd” No “Guts” “p@ssword” No “@#$%1234” No Other interfaces Implementation
  22. 22. Why ATDD? Reason #2: Make progress visible.
  23. 23. Are We There Yet?
  24. 24. Why ATDD? Reason #3: Leverage, Efficiency, and Executable Specifications
  25. 25. Traditional Approaches Requirements Management System Traceability Matrix Test Technical Management Specifications ? System
  26. 26. Efficiency, Reusability, Maintainability Implementation The tests New interface? change? Make a define the Just add a test localized update to requirements. fixture the test fixture. Natural Test “Fixture” … Language Expectations New Interface Implementation (No reconciling (Preserve valid (Leverage relevant multiple, duplicate expectations.) expectations.) artifacts.)
  27. 27. How does ATDD fit with the rest of the process?
  28. 28. ATDD: Part of an Agile Testing Strategy Support Critique Business- facing Acceptance Tests Exploratory Testing Code- Reviews, inspections, facing Unit Tests pairing, code quality metrics (A variation on Brian Marick’s Agile Testing Quadrants as published in his essay “Agile Testing Directions”)
  29. 29. Tests are Versioned with the Code Source Control Natural Language Expectations Test “Fixture” Code Unit Tests Production Code
  30. 30. Tests Execute as Part of the Automated Build Continuous Integration Images courtesy Mike Clark, www.pragmaticautomation.com. Used with permission.
  31. 31. Why ATDD? Reason #4: No more bugs. (No, I’m not kidding. But yes, there is a catch.)
  32. 32. Zero Tolerance for Bugs !"#$%"%&'%( !"#$%"%&'%( )'*+, )'*+,
  33. 33. But Not Everything is a Bug In this context, a BUG is behavior that violates the letter or spirit of the Product Owner’s expectations for the implemented story. If the behavior does not violate expectations related to the implemented stories, it’s an item for the backlog.
  34. 34. Given all that… Why not ATDD?
  35. 35. Resources Adzic, Gojko (2009). Bridging the Communication Gap: Specification by Example and Agile Acceptance Testing. Neuri Limited. Crispin, Lisa (2005). “Using Customer Tests to Drive Development.” Methods & Tools. Summer 2005 Issue. Available online at http://www.methodsandtools.com/ archive/archive.php?id=23 Crispin, L., & Gregory, J. (2009). Agile Testing: A Practical Guide for Testers and Agile Teams (Addison-Wesley Signature Series (Cohn)). New York: Addison-wesley Professional. Marick, Brian (2003). “Agile Testing Directions.” (An explanation of business-facing v. code- facing tests.) Available online at http://www.exampler.com/old-blog/ 2003/08/22/#agile- testing-project-2

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