Bdd: a bit of an experiment

Liz Keogh

@lunivore

March 2015

An Example of an Example

Given Fred has bought a microwave

And the microwave cost £100

When we refund the microwave

Then Fred should be refunded £100.

Examples

Given a context

When an event happens

Then an outcome should occur

Cucumber

Feature: Addition

In order to avoid silly mistakes

As a math idiot

I want to be told the sum of two numbers

Scenario: Add two numbers

Given I have entered 50 into the calculator

And I have entered 70 into the calculator

When I add the numbers together

Then the result should be 120 on the screen

This is what most people associate with BDD

Having conversations

Examples

Given a context

When an event happens

Then an outcome should occur

Can you give me an example?

Is there a context in which this event will create a different outcome?

Examples



And the microwave was on 10% discount



Is this the only outcome that matters?

If we could achieve it with pixies, would it be enough?

Examples




Then the microwave should be added to the stock count.

Turn the outcome into a question!

Given Fred has bought a microwave And the microwave cost £100


Should the microwave be added to the stock count?

Acceptance criteria vs. Scenarios



And the microwave was on 10% discount



Acceptance criteria vs. Scenarios

Given an item was sold with a discount

When a customer gets a refund

Then he should only be refunded the discounted price.

A story about an organisation with partners

several organisations

Whenever we do anything new

we will make discoveries

Deliberate Discovery

Assume ignorance

Assume second order ignorance

Optimize for discovery

Real Options

Options have value

Options expire

Never commit early unless you know why

If a project has no risks,

don’t do it.

Cynefin

Obvious

Complicated Complex

Chaotic

With thanks to

David Snowden and Cognitive Edge

BDD works really well…

…hereish.

How to use scenarios…

…in this

space.

Cynefin Trying

things

out Probe

Experiment

A Safe-To-Fail Probe has…

A way of knowing it’s succeeding

A way of knowing it’s failing

A way of dampening it

A way of amplifying it

Coherence

Coherence

A reason for thinking that the probe might have

a positive impact

Can you think of a scenario

in which this experiment succeeds?

Success Scenarios

Given my boyfriend and I have been going out for four years

When we move in with each other

Then we should be really happy together.

Success Scenarios

Given Fred has signed up for Appytastic

When we sync to Facebook by default

Then Fred’s friends should see how awesome Appytastic is!

Failure Scenarios

Given my boyfriend and I have been going out for four years When we move in with each other

Then we might get on each other’s nerves.

Failure Scenarios

Given Fred has signed up for Appytastic When we sync to Facebook by default

Then Fred and Fred’s friends might see that Appytastic has

massive privacy issues.


We are really happy together.

Fred’s friends see how awesome Appytastic is (and sign up).

Well-formed outcomes

Sensation

Vision

Hearing

Smell

Taste

Success Metrics!

Happiness: 5, 4, 3, 2, 1

Sign-up rate increases (can you think of

an example of how much it increases by?)


We get on each other’s nerves.

Fred and Fred’s friends might see that Appytastic has

massive privacy issues.

Failure metrics!

Annoyance: 5, 4, 3, 2, 1

(but you get what you measure, so measure happiness)

Sign-up rate decreases; proportion of positive tweets decreases

What if a meteor

hits our data centre?

A Safe-To-Fail Probe has…



A way of dampening it

A way of amplifying it

Coherence

A way of avoiding failure completely

Make it cheap to fail.

Given my boyfriend and I have been going out for four years When we move in with each other

Then we might get on each other’s nerves.

(Rent a place together for a year.)

Make it cheap to fail

Given Fred has signed up for Appytastic When we sync to Facebook by default

Then Fred and Fred’s friends might see that Appytastic has

massive privacy issues!

(Put the flag on the server.)

Estimating Complexity

5. Nobody has ever done it before

4. Someone outside the org has done it before (probably a competitor)

3. Someone in the company has done it before

2. Someone in the team has done it before

1. We all know how to do it.

Estimating Complexity

5 4 3

2

1

Complicated Complex

Obvious

Familiarity

5 4 3

2

1

Experts familiar

with scenarios Unfamiliar

scenarios

Familiar

scenarios

Familiarity

5 4 3

2

1 Disaster

movies!

A Naïve Scenario

CONTEXT EVENT OUTCOME

Well-formed outcome

Event which leads to the

outcome

Reality. It’s all good,

right?

Reality. It’s all good,

right?

Subgoals


Well-formed outcome


outcome

Unwanted Context

Unwanted Outcome!

Unwanted Context

Subgoals


Well-formed outcome


outcome

Replacement context

Unwanted Outcome!

Given Scenario


Well-formed outcome


outcome

Unwanted Context

Replacement context

EVENT OUTCOME

Event which leads to

replacement

Changing reality


Well-formed outcome


outcome

Unwanted Context

Replacement context

EVENT


replacement

CONTEXT

Creating options

Is there any context which we could introduce

in which more events

would give us outcomes we want?

Experiment Portfolio

At least one oblique

At least one naïve

Conflicting experiments

Trust is what you do

when you don’t have any options.

Make it safe to fail.

Liz Keogh http://lizkeogh.com @lunivore

Bdd: a bit of an experiment

Software

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