How BDD with tools like Cucumber can create a stronger team, a better quality product, and ultimately a more useable API. Given at the #apistrat SF conference 10/24/2013

1. BDD for APIs
Jason Harmon

2. Jason Harmon
 Blogger @apiux
 API Architect @uShip
 Likes Python
 Works in everything else
 ~20 years of tech experience
 Background in many integrations

3. What is BDD?
 “Behavior Driven Development”
 English readable description of how the product
behaves
 Defined by team up-front: not Dev, QA or product
owned
 Used to verify the acceptance criteria for features in a
product
 Conceptually like TDD (test-first), but for functional
testing (not code architecture)

4. What BDD is NOT
 A testing framework
 Really just an English-readable UI for your own testing
implementation
 A drop-in solution
 You have to write the code
 A UI-testing solution, like Selenium
 You can actually use Selenium as a driver for Uis, but
we‟re talking APIs!

5. * Agile Testing: A Practical Guide for Testers and Agile Teams (AddisonWesley, 2009)
http://lisacrispin.com/2011/11/08/using-the-agile-testing-

6. Supporting the Team
Q2 Automated & Manual
Tests
Business Facing
Functional Tests
Examples
Story Tests
Prototypes
Simulations

7. Polyglot friendly
Cucumber
Ruby-based, the granddaddy of BDD
http://cukes.info

8. Polyglot friendly
Cucumber-JVM
Java implementation, plays nice with
Junit and all JVM languages
Groovy is quite nice here
https://github.com/cucumber/cucumber-jvm

9. Polyglot friendly
Specflow
.NET, Visual Studio integrated
http://specflow.org

10. Polyglot friendly
Lettuce
Python-based, very similar to Cucumber
http://lettuce.it

11. Polyglot friendly
Behat
http://behat.org

12. Gherkin
One Description to Rule Them All
Business Readable
DSL
Not code
https://github.com/cucumber/gherkin

14. Gherkin Example
Imperative Style

15. Gherkin Example
Declarative Style

16. Behavior Driven
 User experience trumps all; APIs are no exception
 Treat API consumers like first class citizens
 Describe how your API behaves from a consumer
perspective

18. Step Definitions

19. Scenarios
“…until it‟s green like a cuke”

20. Scenario outlines

21. Errors
Red means stop

22. Tags
Very useful for grouping features/scenarios
Also useful for ignoring

25. Agreement
Decide during planning how you will test for Acceptance
Criteria
…AS A TEAM…

26. Pushback
 QA might be uncomfortable with code
 Have dev help with a framework, QA can stick to feature
files and simple step definition code
 Dev might not be happy writing tests
 Once they realize QA+PO signs off easy and fast, they‟ll
be convinced
 Product might just be afraid they have to code or learn
something “Techy”
 Once they realize it‟s all about business lingo, i.e.
„Domain Language‟, they‟re fine

27. Productivity
 Stakeholders know what they‟re getting
 Devs know how to build it, less rework
 Testers know how to test it, more time to explore
 Product knows how to sign off, and quickly
 Documentation has a head start

28. Domain Language
 Focus on how you describe everything
 Find agreement on how to describe behavior
 Recognize when behavior is different than before
 “Wait, we‟ve never deleted before!”
 Homework: Domain Driven Design

30. Share!

31. Share!
All BDD tests can be committed to
SCM, including branches
Provides process which allows collaborative
coding on building test framework
Code reviews on changes to test framework are
able to be automated

32. Continuous Integration
Regression is running all the time
Use tags to select the right depth of
regression
Very fast identification of what‟s broken, in
business language

33. Samples
Python/Lettuce
https://github.com/jasonh-n-austin/api-bdd-tests
Groovy/Cucumber-JVM
https://github.com/jasonh-n-austin/TwitterRestTests
.NET/SpecFlow
https://github.com/jasonh-n-austin/TwitterRestTests
Pull requests accepted!

34. Reading material
Posts on BDD with APIs
http://www.pragmaticapi.com/2013/01/12/bdd-atdd-foryour-agile-rest-api/
http://www.pragmaticapi.com/2013/01/21/bdd-atdd-foryour-agile-rest-api-part-2/

35. Thanks
Jason Harmon
@jasonh_n_austin
http://jhr.mn