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Specification-By-Example with Gherkin

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Presentation held on Swiss Requirements Day 2013 in Zurich

Many teams struggle with the implementation of user story acceptance criteria and establishing a shared understanding about the expected story outcomes. This results in missed stakeholder expectations and ad-hoc assumptions made by the team. High efforts for regression testing and the lack of a reliable documentation about the current system behavior are further problems resulting from an unstructured approach to define and validate acceptance criteria.

In this session, you will learn how specification-by-example addresses these problems and overall increases the level of clarity on the project end-to-end. The presentation will cover the theory and practical experience from real projects, with concrete implementation examples based on the Gherkin specification language, that can be used for automated specification validation (available for .NET, Java, Ruby, PHP, JavaScript).

You will leave this session with a fundamental understanding of specification-by-example and its benefits, as well as concrete pointers on how to get started using it in your own projects.

Published in: Technology, Business

Specification-By-Example with Gherkin

  1. 1. FROM STAKEHOLDER EXAMPLES TO LIVING DOCUMENTATION Specification-By-Example with Gherkin Christian Hassa - ch@techtalk.ch - Twitter: @chrishassa Swiss Requirements Day 2013, June 19th 2013
  2. 2. TechTalk Team
  3. 3. 5 • Describe user needs or features • Unit of planning/prioritization Help to say “Not now” – instead of “No” • Future options for evolving the system • Reminder for a conversation • Deferring detail to the last responsible moment What makes user stories agile?
  4. 4. 6 Refining User Stories
  5. 5. 7 Impact Mapping Story Mapping Specification-By-Example Establishing a shared understanding Why? How? Code Epics Deliverables, Outputs Impacts, Outcomes Easier to define upfront Harder to define upfront User Activities User Stories Goals Acceptance Criteria Bug reports Isolated, formalized examples Examples Reminder for a conversation
  6. 6. 8 Collecting Acceptance Criteria “I would try to put a book into the shopping cart …” “I would try to remove a book from the shopping cart…” “I’d check whether the shopping cart is empty, when I enter the shop …” Books can be added to shopping cart. Books can be removed from shopping cart. Shopping cart should be empty when entering the shop. ... ? … As a potential customer I want to collect books in a shopping cart So that I can order several books at once. “Imagine this story is already implemented: how would you verify it?” “I would try to add 1000 books to the shopping cart …”
  7. 7. 9 Using examples
  8. 8. 11 UI wire frames, existing UI rules, key examples existing artifacts, samples Different models of examples
  9. 9. 12 Discussing examples … public void TestInitialOrderDiscount() { Customer newCustomer = new Customer(); Order newOrder = new Order(newCustomer); newOrder.AddBook( Catalog.Find(“ISBN-0955683610”) ); Assert.Equals(33.75, newOrder.Subtotal); } Register as “bart_bookworm” Go to “/catalog/search” Enter “ISBN-0955683610” Click “Search” Click “Add to Cart” Click “View Cart” Verify “Subtotal” is “$33.75” We would like to encourage new users to buy in our shop. Therefore we offer 10% discount for their first order. Original idea for the illustration: George Dinwiddie http://blog.gdinwidiee.com
  10. 10. 13 Specification-by-Example Examples … • make abstract descriptions better understandable However … • examples are usually not formally exchanged or documented Brian Marick Examples Tests Requirements consist of describe verify fulfillment of
  11. 11. 14 Exploring a user need with examples Books in catalogue: Title Author Specification-By-Example Gojko Adzic Impact Mapping Gojko Adzic Explore It! Elisabeth Hendrickson Competitive Engineering Tom Gilb … I want to find books in the catalogue by author and title Search for … Books found … Spec Specification-By-Example Hend Explore It! et Explore It!, Competitive Engineering Context Action Assertion
  12. 12. 15 Key examples: Breaking the model Books in catalogue: Title Author Specification-By-Example Gojko Adzic Impact Mapping Gojko Adzic Explore It! Elisabeth Hendrickson Competitive Engineering Tom Gilb … I want to find books in the catalogue by author and title Search for … Books found … Spec Specification-By-Example Hend Explore It! et Explore It!, Competitive Engineering What happens, if I search for “Explore Specification”? Can I search for single characters, e.g. “e”? Is the number of search results limited, or paged? Is the search also performed in the sub-title of a book?
  13. 13. 16 Discussion of acceptance criteria public void TestInitialOrderDiscount() { Customer newCustomer = new Customer(); Order newOrder = new Order(newCustomer); newOrder.AddBook( Catalog.Find(“ISBN-0955683610”) ); Assert.Equals(33.75, newOrder.Subtotal); } Register as “bart_bookworm” Go to “/catalog/search” Enter “ISBN-0955683610” Click “Search” Click “Add to Cart” Click “View Cart” Verify “Subtotal” is “$33.75” We would like to encourage new users to buy in our shop. Therefore we offer 10% discount for their first order. Original idea for the illustration: George Dinwiddie http://blog.gdinwidiee.com
  14. 14. 17 … illustrated with formalized examples Given the user has not ordered yet When the user adds a book with the price of EUR 37.5 into the shopping cart Then the shopping cart sub-total is EUR 33.75. Original idea for the illustration: George Dinwiddie http://blog.gdinwidiee.com
  15. 15. 18 Discover hidden assumptions Actually, this is not quite right: Books on sale should be excluded. Original idea for the illustration: George Dinwiddie http://blog.gdinwidiee.com
  16. 16. 19 Collaboration: 3 amigos “Happy Path” Technical feasability Exceptions, border cases Original idea for the illustration: George Dinwiddie http://blog.gdinwidiee.com
  17. 17. 20 Abstract acceptance criteria As a shop visitor I want to collect books in my shopping basket so that I can purchase multiple books at once. Books can be added to the shopping basket Books can be removed from the shopping basket Shopping basket is initially empty The same book can be added multiple times to the shopping basket
  18. 18. 21 Examples in Gherkin As a shop visitor I want to collect books in my shopping basket so that I can purchase multiple books at once. Books can be added to the shopping basket Given my shopping basket is empty When I add the book “Harry Potter” to my shopping basket Then my shopping basket should contain 1 copy of “Harry Potter”
  19. 19. 22 As a shop visitor I want to collect books in my shopping basket so that I can purchase multiple books at once. Books can be added to the shopping basket Examples in Gherkin Given my shopping basket contains 1 copy of “Harry Potter” When I add the book “Harry Potter” to my shopping basket Then my shopping basket should contain 2 copies of “Harry Potter” The same book can be added multiple times to the shopping basket
  20. 20. 23 The same book can be added multiple times to the shopping basket Structure of examples Given my shopping basket contains 1 copy of “Harry Potter” When I add the book “Harry Potter” to my shopping basket Then my shopping basket should contain 2 copies of “Harry Potter” Title: Describes intention/abstract acceptance criterion Arrange: Context, initial state of the system Act: Execution of the feature Assert: Assertion of observable behaviour And I should see the warning: “Book already existed in basket” Triple-A constraint “Checks” Chaining up steps
  21. 21. 24 Life time of examples
  22. 22. 25 Purpose of the examples • Shared understanding: acceptance criteria • Documentation: system details • Regression-tests: violated assumptions
  23. 23. 26 Continuous validation with automation Given my shopping basket contains 1 copy of “Harry Potter” When I add the book “Harry Potter” to my shopping basket Then my shopping basket should contain 2 copies of “Harry Potter” System „Step Definitions“ are binding individual steps to an automatable interface of the application. Automatable interface UI Automation Automation does not necessarily have to bind to the UI. Automatability of system is supported/evolving with development.
  24. 24. 27 Demo http://www.specflow.org Gherkin automation for .NET • Visual Studio plugin (VS-Gallery) • NuGet Package
  25. 25. 32 Living documentation
  26. 26. 33 Living documentation Drill into Details (Gherkin scenarios) Overview (Story Map)
  27. 27. 42 Summary
  28. 28. 43 Conclusions • Examples • Illustrate abstract requirements • Trigger new questions: collaborative discovery • Shared understanding • Living documentation • Automatically validated examples • Business readable regression tests • Reliable source of truth • Gherkin based automated examples • Open source, cross-platform • Requirement details versioned with source code • Similar tools: Fit/Fitnesse, Robot Framework, JBehave
  29. 29. 44 Gherkin based automation tools www.cukes.info www.behat.org Ruby, Java, JavaScript, C++ www.specflow.org .NET, Mono, Silverlight, WP7 PHP
  30. 30. 45 Books Gojko Adzic Bridiging the Communication Gap Gojko Adzic Specification by Example Elisabeth Hendrickson Explore IT!
  31. 31. 46
  32. 32. 47 Christian Hassa: ch@techtalk.ch - @chrishassa

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