Off late I am exploring BDD with Cucumber & RSpec in Rails.
The first step in BDD after understanding the customer requirements is to come up with the User Stories in a particular structure. Read this brilliant article from Dan North if you want to know more on the structure of User Story in BDD.
Let’s say I am creating a simple blog app, a sample Scenario for Creating a Post can be written in two ways as shown below. These scenarios are as coded for Cucumber.
A pithy way
Scenario: Create Post
Give I am a registered User
And I have signed in
When I go to Create Post Page
And Create a Post and Publish it
Then I should see the Post in the Index Page
or a Detailed way
Scenario: Create a Post
Given I am a registered User with name "Arun", email "firstname.lastname@example.org" and password "foobar"
And I sign in as "email@example.com/foobar"
When I visit Create Post Page
And I fill up Title as "Foo Post"
And I fill up Content as "Bar Contents for Foo Post"
And I publish the Post
Then I should see message "Post was successfully created."
And I should see post in the index page
The RSpec Book touches on this topic. It calls the first approach Declarative Style and second one Imperative Style. The Book also advises to use the former way if the project is more like a single man show where developer dons analyst/tester/coder hats and go for 2nd approach if the project has a bigger team and a business analyst for writing scenarios.
But its really a touch and go topic and its really difficult to gauge to how much in depth we have to go. The declarative seems to be pretty concise with loaded step definitions, but the imperative style gives a fair idea of what it takes to accomplish something in the system. So if we have a little bit informed tech savvy customer, probably second approach may add lot of value and clear lot of confusion. The imperative style is kind of walking the customer through the UI flows of the system.
But the conundrum with imperative style is if we already have good RSpecs for the Views/Controllers our RSpecs may read a lot like the imperative scenario and may look redundant.
So I can do
rspec spec --format doc to get detailed documentation of the flows like the Cucumber imperative style. But of course it may not be good idea to share RSpecs with a Business User.
As the RSpec book says perhaps we need to mix judiciously both and perhaps experience only will teach to balance that.
The trigger for me to write this post was I was trying to create Scenarios for a sample project I am doing and just one hour I spend switching a scenario between declarative and imperative and was pretty confused where I would/should settle.