LegacyCoderetreatMilano 2013

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10 PRINT "Hello World"20 Go to 10

#lcrm13

Format of the Day

from 10:00 to 13:00

MORNING

from 13:00 to 14:00

LUNCH

from 14:00 to 17:00

AFTERNOON

45 min coding10 min retrospective5 min break

Format of the Day

45’ coding10’ review5’ break

•CHALLENGE•REPEAT•FEEDBACK

DEEPPRACTICE

NO PRESSURE

feel free toexperiment

NO PRESSUREdo not completethe task but master it

Practice

Refactoring

•AUTOMATIC•MANUAL

Read Code

TestCode

CharacterizeBehaviour

Design

•BY CODE•BY TESTS•BY SMELLS

Rules

When youdon’tpair...

aftereach

session

Pair

DELETEYOURCODEAFTEREACHSESSION

Playbook

Golden Master(aka characterization tests)

session #1

# suppose that our legacy code is this program called ‘game’$ game > GOLDEN_MASTER

# after some changes we can check to see if behaviour has changed$ game > OUT-01$ diff GOLDEN_MASTER OUT-01

# after some other changes we check again and...$ game > OUT-02$ diff GOLDEN_MASTER OUT-02

# GOLDEN_MASTER and OUT-01 are the same

# GOLDEN_MASTER and OUT-02 are different -> behaviour changed

Golden Master(aka characterization tests)

# what about something with a random output?$ whatthecommit> I think I fixed a bug :-)> for great justice.> syntax> LOL!> ...

# somewhere in the code...$ cat whatthecommit | ack -i ‘rand’> 5: g = Random.new> 42: messages[g.rand(NUMBER_OF_MESSAGES)]

Golden Master(aka characterization tests)

# sequence generators are initialized with a seed# two random sequence generators initialized with the same# seed are going to produce the same sequence of numbers

$ irb1.9.3 > g = Random.new1.9.3 > (1..10).map{g.rand(1000)} => [691, 362, 997, 692, 236, 532, 687, 616, 218, 702]1.9.3 > g = Random.new 1.9.3 > (1..10).map{g.rand(1000)} => [865, 186, 89, 382, 894, 708, 769, 850, 452, 85] 1.9.3 > g = Random.new(1)1.9.3 > (1..10).map{g.rand(1000)} => [37, 235, 908, 72, 767, 905, 715, 645, 847, 960] 1.9.3 > g = Random.new(1)1.9.3 > (1..10).map{g.rand(1000)} => [37, 235, 908, 72, 767, 905, 715, 645, 847, 960]

Golden Master(aka characterization tests)

# we need to change the code to take somehow the seed $ whatthecommit --seed=42> fix the bug, for realz> to those I leave behind, good luck!> herping the derp> changes> ...

# so that with the same seed, the same code is going to# create the same output$ whatthecommit --seed=42> fix the bug, for realz> to those I leave behind, good luck!> herping the derp> changes> ...

Golden Master(aka characterization tests)

$ git clone https://github.com/gabrielelana/trivia.git$ cd triva# enjoy

session #1Characterize the behaviour of the code with the golden master technique

Test Code

# to get the already done golden master$ git merge golden-master

session #2

Refactoring & Design

Refactor the code so that it will be easy to create a newcategory of questions

session #3

Test Code

Put undertest therollmethod/function

session #4

Read Code

Mark all the smells in the code. Remove at least 3 of them

session #5

Remove all the duplication

session #6Replacing the penalty rules should be a one line change!