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.

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. TechTalk Team

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. 6
Refining
User Stories

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. 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. 9
Using
examples

8. 11
UI wire frames,
existing UI
rules, key examples
existing artifacts,
samples
Different models of examples

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. 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. 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. 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. 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. 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. 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. 19
Collaboration: 3 amigos
“Happy
Path”
Technical
feasability
Exceptions,
border cases
Original idea for the illustration: George Dinwiddie
http://blog.gdinwidiee.com

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. 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. 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. 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. 24
Life time of
examples

22. 25
Purpose of the examples
• Shared understanding:
acceptance criteria
• Documentation:
system details
• Regression-tests:
violated assumptions

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. 27
Demo
http://www.specflow.org
Gherkin automation for .NET
• Visual Studio plugin (VS-Gallery)
• NuGet Package

25. 32
Living
documentation

26. 33
Living documentation
Drill into Details
(Gherkin scenarios)
Overview
(Story Map)

27. 42
Summary

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. 44
Gherkin based automation tools
www.cukes.info
www.behat.org
Ruby, Java, JavaScript, C++
www.specflow.org
.NET, Mono, Silverlight, WP7
PHP

30. 45
Books
Gojko Adzic
Bridiging the
Communication Gap
Gojko Adzic
Specification by
Example
Elisabeth Hendrickson
Explore IT!

31. 46

32. 47
Christian Hassa: ch@techtalk.ch - @chrishassa