Testing Requirements with

BDD

Alan Parkinson@alan_parkinson

The Requirements Crisis

We like to solve

complex problems

Scope creep

Solution

Simple

Bug Tennis

Developers

Vs

Testers

The Requirements Crisis

50-60% of all defects are requirement

defects

A User Story is just a placeholder for a conversation

between the three amigos

Illusion of transparency

tendency for people to overestimate how well they understand others' personal mental states

Acceptance Criteria

Rules are difficult to communicate

People end up with a fuzzy understanding

Can you give me an example?

Upgrade Gold and Platinum Loyalty members to Superior Rooms if

available

BDD uses examples to illustrate behaviour

Demonstrates how acceptance criteria behaves in a particular situation from a

particular point of view

BDD uses examples to illustrate behaviour

Given a guest with a standard room reservationAnd the guest is a gold loyalty memberAnd there are superior rooms availableWhen the user checks in the guestAnd a superior room is availableThen the guest should be upgraded to the superior room

Examples raise questions….

How do we decide if a room is available?

What if a room is not available. Do they get a alternative reward?

Is superior a room type or just any room better than

a standard room?

Donald Rumsfeld, a BDD thinker

there are known knowns; there are things we know we know.

We also know there are known unknowns; that is to say we know there are some

things we do not know.

But there are also unknown unknowns ”

“

There is no such thing as a dumb question

“unknown knowns”

Information we know about but

are not willing to consider… often seen in “group think”

Deeper examples

Given a guest with a standard room reservationAnd the guest is a gold loyalty memberAnd there are superior rooms availableWhen Roy the receptionist checks in the guestAnd a superior room is availableThen the guest should be upgraded to the superior room

Use real people, roles or actorsGiven a guest with a standard room reservationAnd the guest is a gold loyalty memberAnd there are superior rooms availableWhen Roy the receptionist checks in the guestAnd a superior room is availableThen the guest should be upgraded to the superior room

Given a guest with a standard room reservationAnd the guest is a gold loyalty memberAnd there are superior rooms availableWhen Roy the receptionist checks in the guestAnd a superior room is availableThen the guest should be upgraded to the superior room

Actors vs Personas

Deeper examples

Given a guest with a standard room reservationAnd the guest is a gold loyalty memberAnd there are superior rooms availableWhen Roy the receptionist checks in the guestAnd a superior room is availableThen the guest will be upgraded to the superior room

Inject Uncertainly with “should”Given a guest with a standard room reservationAnd the guest is a gold loyalty memberAnd there are superior rooms availableWhen Roy the receptionist checks in the guestAnd a superior room is availableThen the guest should be upgraded to the superior room

Which come first:Acceptance Criteria or Examples?

Neither!

Both can be used to discover the other

Ask the Product Owner: Can you give

me an example?

Iterator over the context to discover new Examples

Given a guest with a standard room reservationAnd the guest is a gold loyalty memberAnd there are superior rooms availableWhen the user checks in the guestAnd a superior room is availableThen the guest should be upgraded to the superior room

Given a guest with a standard room reservationAnd the guest is a gold loyalty memberAnd there are superior rooms availableWhen the user checks in the guestAnd a superior room is availableThen the guest should be upgraded to the superior room

Given a guest with a king room reservationAnd the guest is a platinum loyalty memberAnd there are superior rooms availableWhen the user checks in the guestAnd a superior room is availableThen the guest should be upgraded to the superior room

Examples change our style of writing and

automating

Given a customer “alan” exists with password “secret”

And I am not logged in

When I navigate to the account page

Then I am redirected to the login form

When I enter the “username” with “alan”

And I enter the “password” with “secret”

And I press “login”

Then I am redirected to my account page

Given a customer “alan” exists with password “secret”

And I am on the login form

When I enter the “username” with “alan”

And I enter the “password” with “secret”

And I press “login”

...

...

Imperative style

Command driven, List of instructions, explicit steps on how

to do something

Given a customer “alan” exists with password “secret”

And I am not logged in

When I navigate to the account page

Then I am redirected to the login form

When I enter the “username” with “alan”

And I enter the “password” with “secret”

And I press “login”

Then I am redirected to my account page

What if we wanted to change our Authentication

Method?

We would have to change every mention of the login form

in our tests

That`s a pretty brittle piece of Automation

Largest cause of Story based Automation failures

Declarative style

Describes what to do but not how to do it

“How should it Behave?”

not

“How should I Test it?”

Given a customer “alan” exists with password “secret”

And I am not logged in

When I navigate to the account page

Then I am redirected to the login form

When I enter the “username” with “alan”

And I enter the “password” with “secret”

And I press “login”

Then I am redirected to my account page

Given I am an unauthenticated customer

When I attempt to view the account page

Then I am asked to authenticate

When I authenticate with valid customer

credentials

Then I am shown the account page

Test related details are pushed down into step

implementations

Simple to maintain… Only the step definition

needs to change

Given a customer “alan” exists with password “secret”

And I am not logged in

Given I am an unauthenticated customer

When I navigate to the account page

Then I am redirected to the login form

When I attempt to view the account page

Then I am asked to authenticate

When I enter the “username” with “alan”

And I enter the “password” with “secret”

And I press “login”

When I authenticate with valid customer

credentials

Questions

Testing Requirements with

BDD

Alan Parkinson

@alan_parkinson