Behavior-Driven Development for Everyone

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### <a href="https://twitter.com/schmonz">@schmonz</a>

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# Behavior-Driven Development<br />for Everyone

## Amitai Schleier

### 2018/01/18

???

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2. Press 'P' to show these here presenter notes

### 90 minutes

Problems are better solved when you're better involved. That's how you
make your living, and that's what BDD is all about. We'll work together
to solve a problem in a way we can all understand and trust, expressing
what we want in plain English and automating our tests with a tool
called Cucumber. Don't worry, you won't be put on the spot at the
keyboard -- I'll handle all the coding!

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1. **Learn** what BDD _isn't_, and what it is
2. **See** an approximation of what BDD can be like
3. **Consider** the possible value of BDD in your context
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- Basically the same as Test-Driven Development
- Programmers do it behind the scenes
- A kind of automated test
- A software tool
- Requires a software tool
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- Everyone on the team does it **together**
- A shared focus on overall **system behavior**
- Enough **shared language** to deliver on that focus
- _May_ result in **automated acceptance tests**
- _May_ be more valuable with a **supporting tool**
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## Can we use it to **work together more effectively**?

## If we can't, then it's not important!

## If we can, then it is.
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I'm not a great programmer. Especially in front of a crowd.

I'm hardly a BDD expert. I've **learned by doing**, and continue to.

BDD is most useful when applied by people who:

- Want to do work that **matters**
- Accept the **limits** of their knowledge
- Are willing to **ask** for, and **offer**, help
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If I develop it **all by myself**, there's **no BDD**.

If we think, try, check, learn, and solve it **together**, that might well be BDD.

It helps to focus on the smallest end-to-end **system behavior** we want next.

It helps to use **words we all understand** in the same way.

It helps to use our words of understanding to **verify the system**.

_If_ we want to verify our understanding automatically, we can use a
**software tool**.
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## BDD relies on examples.

## BDD might be best explained **with** examples.
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For every role that has an interest in what it means for a story to be
**valuable**, **ready**, and **done**, let's hear from someone
representing that interest. Usually one each of:

- Product Owner
- Tester
- Developer

Let's use what we hear to build a shared understanding.
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I'm going to write some code to solve a problem.

I promise to help you understand and trust that the code solves the problem.

Do you promise to help me solve it?
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Before we start working, let's split into three groups:

- Product Owners
- Testers
- Developers

Join a group you're not usually part of. I promise you will **not** be put
on the spot.
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I'll briefly explain the rules of FizzBuzz.

Questions?

Let's go!
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I'll briefly explain what I know of the rules of bowling.

Our job is to keep score for one player's game.

Questions?

Let's develop!
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Why did it say "4 tests"? It didn't look like 4 tests.

Running verbosely, we can see what's counted as a test:

```
:; prove -v
t/cucumber.t ..
ok 1 - require './bin/game.pl';
#        Feature: Compute bowling score
#            As a very amateur bowler
#            I want the score to be computed for me
#            So that all I need to do is pretend I'm aiming
#
#            Scenario: Gutter game
ok 2 -          Given a new game
ok 3 -          When I knock down 0 pins 20 times
ok 4 -          Then my score is 0
#
1..4
ok
All tests successful.
```
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- Different groups sliced differently:
    - Total rolls
    - Frames
    - Number of rolls per frame
    - Perfect game first!?!?!
- Within one group: disagreed, split, tried both in parallel, got back together and picked one
- In conversation, we could refer to scenarios by name
- Struggled with priority: which scenarios first?
	- One solution: just ideate (and defer prioritizing)
- We wrote lots of scenarios all at once, based on our understanding of the entire game of bowling
- Another approach: one new scenario at a time, implementing as we go, reflecting on what we learn
- Everyone understands bowling better than they did an hour ago!
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- Some folks might try this BDD way of talking in their jobs tomorrow
- Three Amigos: attend sometimes, observe and contribute ("if you see something, say something")
- You don't have to say "Given, When, Then", but it tends to aid shared understanding
- Who writes the scenarios? Everyone in the room. Doesn't matter who records them. Take turns.
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- Why were examples so helpful for understanding?
    - The simplistic formula we tried broke down
    - Abstract language leaves lots of room for miscommunication
    - Specific examples reveal shallow agreement, so we can seek deeper agreement
- AKA <a href="https://en.wikipedia.org/wiki/Specification%20by%20example">Specification by example</a>
- One set of examples that often helps: James Grenning's [ZOMBIES](http://blog.wingman-sw.com/archives/677)
- In a UX context? Examples might look like wireframes. Still useful, as are the words "Given When Then"
    - Llewellyn pointed us at a video: [Nordstrom Innovation Lab: Sunglass iPad App Case Study](https://www.youtube.com/watch?v=szr0ezLyQHY)
- Can your customers understand your scenarios? Probably! (Hey, maybe invite one to Three Amigos!)
- Don't use Perl
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- [Introducing BDD](http://dannorth.net/introducing-bdd/) ([Dan North](https://twitter.com/tastapod), dannorth.net, March 2006)
- [The Three Amigos: All For One, One For All](http://www.stickyminds.com/sites/default/files/magazine/file/2013/3971888.pdf) ([George Dinwiddie](https://twitter.com/gdinwiddie), _Better Software_, November/December 2011)
- [What is BDD?](http://lizkeogh.com/2015/03/27/what-is-bdd/) ([Liz Keogh](https://twitter.com/lunivore), lizkeogh.com, March 2015)
- [The Bowling Game Kata](http://butunclebob.com/ArticleS.UncleBob.TheBowlingGameKata) ([Robert C. Martin](https://twitter.com/unclebobmartin), butunclebob.com, 2005)
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# Behavior-Driven Development<br />for Everyone

## Amitai Schleier

## [latentagility.com](https://latentagility.com)