tdd with lego at sdec13

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Bryan Beecham and Mike BowlerTDD with LEGO

Monday, 11 November, 13

Understanding TDD with LEGO

Bryan Beecham@BillyGarnet

Mike Bowler@mike_bowler

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Exercise - 1

Open up one LEGO packet

Build a person and a house out of LEGO

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Admire your work

Take a photo. Upload to Twitter. Brag to your friends.

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Reference

Test-DrivenDevelopmentBy ExampleKent Beck

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What is the goal of TDD?

It creates clean code that works ~ Ron Jefferies

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TDD

It is a predictable way to develop. You know when you are finished, without having to worry about a long bug trail.

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TDD

It gives you a chance to learn all of the lessons that the code has to teach you. If you only slap together the first thing you think of, then you never have time to think of a second, better thing.

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TDD

It improves the lives of the users of your software.

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TDD

It lets your teammates count on you, and you on them.

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TDD

It feels good to write it.

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The MantraRed - Green - Refactorphoto from doolwind.com

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The Mantra - Red

Write a small test that doesn’t work

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The Mantra - Green

Do the minimum to make the test work

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The Mantra - Refactor

Eliminate duplication

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Exercise - 2

Build a person and a house with TDD

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Prepare your environment

Clear the area in front of you. This is your program.

The perfect program!

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First Test

Does the person exist? No?

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Hurray!!!We failed the test! Celebrate! High 5s!

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Minimum to pass the test

Add a block. Can that be a person?

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Hurray!!!

The person now exists!

Not very impressive but it could represent a person.

We passed the test! We are rocking now!

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Refactor

Remove any duplication. In this case we’re good.

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Same thing for house

Blah, blah, awesome recreation by speaker...everyone is extremely impressed and are thinking this might be the best session of the whole conference.

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We need a new test

The house is taller then the person.

Assert.IsTrue(house.height > person.height);

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Hurray!!! - More FailureThe person is the same size so we fail this test. Well done!

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Failure = Learning Opportunity

If you’re not failing, you’re not learning.

If you’re not learning...

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Minimum to pass the test

From the audience this time. Anyone? Bueller?

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Hurray!!! - Success

Alright, we passed the test.

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Refactor

Still very simple. Still nice and clean.

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Software Requirements

Software must do three things:

It must work

It must be understandable

It must be updatable

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We need a new test

Is the house wider then the person? No?

We failed another test! Awesome! We are learning a lot about improvements that are needed to our code.

Let’s do the minimum to pass the test.

Any duplication to remove?

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We need a new test

Can your person fit in the house? Yikes! No.

We failed another test! Awesome! We are learning so much about what our customer needs.

Let’s do the minimum to pass the test.

Any duplication to remove?

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Exercise - 3 Partners!

Break into groups of two for this next exercise.

When developers do this we call it Pair ProgrammingBerkley photo from the web

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New Requirements

Your new program needs to have:

A person

A house

A tree

An animal

A vehicle

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Let’s Practice!Work together and write down a new test

Build minimally pass the test

Repeat (Don’t worry about Refactoring for now)

Here’s a few if you get stuck:

Is the house at least x bricks tall?

Is the tree the same size as the house?

Is the animal smaller than the person?

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New Requirements

Your new program needs to have:

A person

A house

A tree

An animal

A vehicle

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Review

Let’s take a minute to walk around and look at everybody’s creations!

Taking breaks and stretching your muscles (eyes, legs, arms, back) is very important to stay healthy.

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Apology

You may have to break your wonderful new structures for the components for the next section.

Don’t worry, there is more building to come!

Please do take a photo. Remember @BillyGarnet and @mike_bowler #SDEC13 if you’re tweeting about the amazing time you’re having!

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Refactoring

Refactoring is the process of changing a software system in such a way that it does not alter the external behaviour of the code yet improves its internal structure.~Martin Fowler

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Super Fast BreakStand up and stretch - really, it’s important!Share something you’ve learned with a neighbour!

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Exercise 4 -Team Build

Each table will come up with a large structure with lots of parts to build. (airport, zoo, amusement park...)

You will be a software team, working in pairs, contributing to the large team structure (the build) at your table.

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Decide on an idea

Shh...don’t tell the other tables.

(Jeopardy music...)

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Break it into components

Take a minute to write out a few of the components that need to be built (product backlog).

Each pair will build a component through TDD.

We will then add the sections to the big project. Make sure you don’t break your teams tests!

Write your test on paper, fail, then add lego to pass.

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Demo time!

A few teams will now present their creation.

Please share the tests that you came up with and point out the solution.

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Review

Test-Driven Development / Design

Refactoring

Pair Programming

A bit of developer speak

Experience working on a software team

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Questions?

Bryan Beecham@BillyGarnetbbeecham@fusebill.com

Mike Bowler@mike_bowlermbowler@gargoylesoftware.com

Please separate the lego bricks into their respective colours

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No really, it’s over

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There are no more slides

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No trailers

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Looking for more?

Check out http://www.humanrefactor.com

Links to HumanRefactoring, and soon more LEGO!

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