The document discusses test-driven development (TDD) and behavior-driven development (BDD) when testing in F#. It outlines some popular unit testing frameworks that can be used in F# like NUnit, xUnit, and MsTest. It also discusses fluent interfaces like FsUnit and FsTest for writing tests. The document then discusses the principles of agile development and BDD, including writing user stories and acceptance tests in a natural language. It notes benefits of TDD and BDD like facilitating change, providing documentation, and improving design. Finally, it discusses some BDD frameworks for F# like SpecFlow, TickSpec, and NaturalSpec and provides an example of writing a BDD specification.

1. TDD & BDD
Testing in F#
Phil Trelford and Chis Marinos
Progressive F# Tutorials 2011

2. Organization
 REPL
 REPL Task
 TDD
 Introduction
 Unit Testing Tasks
 BDD
 Introduction
 Acceptance Testing Tasks

3. Unit Testing Frameworks
 F# supports all major unit testing frameworks
 NUnit
 xUnit
 mbUnit
 MsTest
…

4. Fluent Interfaces
 FsUnit
 FsTest
 NaturalSpec

5. FsUnit
[<Test>]
let ``when player A wins the score should be 15-0`` () =
[A]
|> scoreGame
|> should be (equal (Points(Fifteen,Zero)))

6. Agile Manifesto
 Individuals and interactions over
processes and tools
 Working software over
comprehensive documentation
 Customer collaboration over
contract negotiation
 Responding to change over
following a plan

7. Collaboration
Developer Customers
Business
Testers
Analyst

8. User Stories

9. Acceptance Tests
Refunded items should be returned to stock
 Given a customer buys a black jumper
 And I have 3 black jumpers left in stock
 When he returns the black jumper for a
refund
 Then I should have 4 black jumpers in stock

10. Test Driven Development
(TDD)
Benefits
 Facilitates change
 Refactoring
 Regression Testing
 Documentation
 API
 Living Documentation
 Design
 Classes, Methods
 Behaviour

11. Unit Testing
“A good unit test needs both to illustrate and
define the behavioural contract of the unit
in question. Behaviour is more than just
individual methods…” – Kevlin Henney

12. Behaviour Driven Development
(BDD)
“Is an agile software development technique that
encourages collaboration between
 Developers
 QA
 Business Participants
in a software project.”
“It extends TDD by writing test cases in a
natural language that non-programmers can read.”

13. Behaviour Driven
Development (BDD)
Benefits
 Facilitates Change
 Refactoring
 Regression
 Rewriting
 Documentation
 Behaviour
 Living Documentation
 Domain Language
 Defines Done
 When all tests pass

14. Team Workshops

15. BA + Developer + QA

16. Testers find holes

17. BDD Frameworks
External DSL Internal DSL
 Cuke4Nuke  MSpec
 NBehave  NaturalSpec
 StorEvil  NSpec
 SpecFlow  SpecsFor
 TickSpec  StoryQ

18. Declarations
Gherkin NaturalSpec
Given I input 5 [<Scenario>] let
When calculating the factorial ``When calculating factorial of 5 it
Then the result is 120 should equal 120``() =
Given 5
|> When calculating factorial
|> It should equal 120
|> Verify

19. First Steps in BDD on .Net
• Shell
StorEvil
• C# & F#
Gherkin
NUnit
• Visual Studio Visual
SpecFlow Studio
• C#
?
• F# & C#
?
• VS & Shell

20. Look no hands

21. Look no hands

22. TickSpec

23. Demo

24. Task: BOGOF
 As a retailer I want to offer my customers buy
one get one free promotions

25. Step away from the tools
“Start by having conversations, engaging both
testers and business stakeholders
If you can’t have those conversations, stop.
You can’t do BDD” – Liz Keogh

26. What makes a good feature file
 About the business domain
 In domain language
 Specification – not a script
 Easy to understand
 Focused on a single thing
 Precise and testable
 Self-explanatory
 Consistent
 Easy to access

27. BDD Patterns: Tables
Scenario: Winning positions
Given a board layout:
| 1 | 2 | 3 |
| O | O | X |
| O | | |
| X | | X |
When I mark X at middle right
Then I win

28. What makes a bad feature file
 Long sentences
 Repetitious sentences
 Repetitive scenarios
 A never ending story
 Commentary
 And another thing

29. BDD Patterns: Examples
Scenario: Winning positions
Given a board layout:
| 1 | 2 | 3 |
| O | O | X |
| O | | |
| X | | X |
When I mark X at <row> <col>
Then I win
Examples:
| row | col |
| middle | right |
| middle | middle |
| bottom | middle |

30. Terry's Chocolate Oranges sold
for just 29p each
Two simultaneous
promotions:
 three-for-£5 offer
 buy-one-get-one-free
Equals:
 £2.75 product
 Sells for 29p

31. Yum!

32. BDD Books

33. Lifetime BDD Awards
@tastapod
@lunivore
@gojkoadzic

34. Q&A