Keeping your codebase as cool as a Cucumber

Tanya Powell / @tanya_powell

I'm a Software Engineer at Gamesys
I volunteer at EmpowerHack
I'm a Board Member for Women Hack For Non-Profits
I volunteer at Chayn
I'm one half of an amazing podcast called A Large G&T

What is Behaviour Driven Development (BDD)?

BDD in Nutshell

(Photo Credit: It's a Delivery Thing)

U w0t Mate

Imagine we are making a simple calculator that only adds two small numbers together
We can assume that we display: 2 + 2 = 4
Actually our domain expert expected our calculator to display: 2 + 2 = FOUR

Our Assumption Implemented	The Expectation Implemented
When we print out `addTwoNumbers(2, 2)` we will be returned `4`	Our answer will now be returned as `FOUR`

BDD vs TDD

Behaviour Driven Development (BDD)	Test Driven Development (TDD)
Customer friendly language, e.g. `$(count).should_be(5)` Expresses what the application needs to do for the stakeholder to find acceptable Ensures the right application is built	Developer friendly language `assertEquals(count, 5)` Aimed for developers to help them check their software designs Ensures you build the application correctly

How to use BDD?

Can be used with:

Ruby	Java	Python	Javascript
Clojure	.NET	PHP	C++

Gherkin

Gherkin

Cucumber's Domain Specific Language that allows you to describe the expected behaviour
Its two purposes are documentation and automated tests

Gherkin Keywords

Feature	Background	Scenario	Given
When	Then	And	But
*	Scenario Outline	Examples

Simple Feature Template (Feature Injection)

In order to { meet some goal }

As a { type of stakeholder }

I want { a feature }

Scenario: Adding Two Numbers

Writing The Tests

Results

Why use BDD?

It's simple and can improve team communication
The developer will know what to build
The tester will know what to test
The domain expert knows what bahaviour to expect

Thanks for listening

http://tanyapowell.co.uk/intro-to-bdd-talk/

You can talk to me here @tanya_powell