Stories, Rules and Examples @mattwynne | BDDX 2014 London 

Rules vs Examples AKA, The Passwords Game 

Form teams • Need an even number of teams • 2-4 people per team 

In order to prevent passwords from being guessed, Users must be forced to create strong passwords 

Create 3 rules • In your team, invent 3 rules for what makes a valid password • Keep the rules secret from the other teams • Be imaginative, and have a bit of fun • Examples: "It must have an @ in it" "It must not be the name of a fruit" 

Create 3 examples • Create 3 examples that illustrate your rules. • Scribble each one on a post-it note • Examples: "@pple" => valid "apple" => invalid "tom@to" => valid 

Guess the rules! • Pass your examples to another team. • Let them try to work out what your rules might be. 

Clarify with examples • As a guessing team, you can create new examples and ask them to be checked by the team whose rules you're trying to guess. • One example at a time. • How many examples will it take to guess the rules correctly? 

So... 

What was missing? 

Complete the following sentences • Examples are better than rules because… • Rules are better than examples because… • Examples without rules are like… • Rules without examples are like… 

We need rules and examples 

Use examples to illustrate the rules 

User Story Rules / Acceptance Criteria Examples Describe each of these in your own words