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TDD + JavaScript

From „wtf“ to „hell yeah“

Wolfram Kriesing, uxebu @wolframkriesing

My slides are english

Refaktorisierung

Einheitentest

Akzeptanztest

Paar-Programmierung

How I wish to be programming …

Still learning not to …

Sche

dule

Intro No Ping Pong TDDing Baby steps GSpread

break

we hack

What is (Software) Craftsmanship?

Journey

endless journey

https://leanpub.com/socra

Hello

Something about me …

About you …

JavaScript - Var(ious) #1

http://dmitry.baranovskiy.com/post/91403200

JavaScript - Var(ious) #2

JavaScript - Var(ious) #2.1

JavaScript - Var(ious) #3

JavaScript - Var(ious) #4

Let’s hack

Roman numerals

1 I

5 V

10 X

50 L

100 C

500 D

1000 M

• build as much as you can• 30min• estimate if you get it done• GO

IV - 4IX - 9

XII - 12XIX - 19XLIX - 49

Did you get it done?

Do you like your code?

Do you know it works?

Did you have a strategy?

Did you write on paper?

Let’s say you have to add a feature.Will all the rest still work?

Is your code maintainable?

What is TDD?

TDD is no Replacement for

OO Design (Patterns)SOLIDDRY

but helps detect deficiencies

Law of Demeter

aim of TDD: help to get

a good design side effect: unit tests

Step by Step

Step 1

Find a deficiencywrite it out in code, in a test

• focus • constrain the problem

Step 2

Design (the API)because test code uses it

• we get feedback • we understand testability

„TDD is no better than it’s driver“

http://www.davesquared.net/2011/03/why-learning-tdd-is-hard-and-what-to-do.html

Quick feedback

Se

ssio

n #

2

Code Kata

Code Kata

first mentionedby Dave Thomas

(co-author of the book The Pragmatic Programmer)

Code Kata

to improve your programming skills

by challenging your abilities

and encouraging you to find multiple approaches

is a small exercise

Coding Dojo

•First Coding Dojo in France

•Practice - like a musician

•TDD

•Pair Programming

•Safe Environment

•No deadlines

•Improve your skills

CodeRetreat

CodeRetreat

5x

one day long

intensive exchange

CodeRetreat

coderetreat.org

JS CodeRetreat

jscoderetreat.com

TDD #1

Choose a pair!Someone you never worked with!

Basic rules

• One types, the other tells what to type

• Write a failing test first

• Do as little as possible to make it green

• Switch roles on green

Roman numerals

1 I

5 V

10 X

50 L

100 C

500 D

1000 M

• Implement 1..?• you got 45 minutes• no estimate• GO

Throw away your code At least don’t use it in session #2

Retro #1

Where is TDD?

Cost, Time, Effort

Functional Tests Integration Tests Exploratory Tests

Manual Tests …

Unit Tests

TDD #2

Choose a new pair!

Basic rules

• One types, the other tells what to type

• Write a failing test first

• Do as little as possible to make it green

• Switch roles on green

• Improve over last time!

Roman numerals

1 I

5 V

10 X

50 L

100 C

500 D

1000 M

• Implement 1..?• 45 minutes• no estimate• GO

Retro #2

What is TDD?

Kent Beck rediscovered TDD in 2003

encourages simple designs

Beck, K. Test-Driven Development by Example, Addison Wesley - Vaseem, 2003

inspires confidence

confidence

confidencesimple design

Helps Design

Easy to Test? Simple Design?

What is a unit test?

Testability

What is a unit?

Tennis Session #1 AAA

http://blog.mikemccandless.com/2014/08/scoring-tennis-using-finite-state.html

love all

while true; do npm test; sleep 3; done;

Tennis Session #2 4 rules of simple design

4 rules of simple design

http://c2.com/cgi/wiki?XpSimplicityRules

1) pass all tests

4 rules of simple design

http://c2.com/cgi/wiki?XpSimplicityRules

1) pass all tests

2) clear, expressive and consistent

4 rules of simple design

http://c2.com/cgi/wiki?XpSimplicityRules

1) pass all tests

2) clear, expressive and consistent

3) no duplication

4 rules of simple design

http://c2.com/cgi/wiki?XpSimplicityRules

1) pass all tests

2) clear, expressive and consistent

3) no duplication

4) small and simple code

GO!

Step 1 - Think

Step 2 - Write a test

Step 3 - How much does this test suck?

Step 4 - Run the test and watch it fail

Step 5 - Write just enough code to make it pass

I wrote too much code last time.

I SHOULD STOP DOING THAT!

Step 1 - Think

Step 2 - Write a test

Step 3 - How much does this test suck?

Step 4 - Run the test and watch it fail

Step 5 - Write just enough code to make it pass

TDD - J.B. Rainsberger

Step 1 - Think

Step 2 - Write a test

Step 3 - How much does this test suck?

Step 4 - Run the test and watch it fail

Step 5 - Write just enough code to make it pass