Refactorer du legacy, même pas peur! Agile France

Refactorer legacy, même pas peur!

Johan MARTINSSON Développeur - Indé[email protected]@johan_alps

Rémy SANLAVILLE Développeur - Orange Software

[email protected]@sanlaville

mailto:[email protected]


https://twitter.com/johan_alps

https://twitter.com/johan_alps


https://twitter.com/sanlaville

https://twitter.com/sanlaville

Working with Legacy Code

LEGACY CODETESTS

REFACTORING

TESTS


LEGACY CODE

REFACTORING

Refactoring Legacy Code with Object Calisthenics2012 - 2013

Anonymous Developers - Season 1

TESTS


LEGACY CODE

REFACTORING

100% Legacy Code Coverage with Golden Master201

4


Le problème – dans le legacy

Long d’écrire les tests

Les tests haut niveau sont longs à éxécuter

Les tests unitiare adhèrent au code


LEGACY CODE

REFACTORING

100% Legacy Code Coverage with Golden Master201

4


TEMPORARY REFACTORING

TESTS

MAINTAINABLE TESTS


LEGACY CODE

REFACTORING

MAINTAINABLE TESTS


TESTS

Don’t forget to replace tempory

refactoring tests by maintainable

tests

Trivia Challenge http://www.hasbro.com/games/en_US/shop/details.cfm?R=93C6EE71-6D40-1014-8BF0-9EFBF894F9D4:en_US

https://github.com/jbrains/trivia

It simulates a trivia gameusing a randomizer

for correct and wrong answers

How long do you need to reach ~100% code

coverage ?

http://www.hasbro.com/games/en_US/shop/details.cfm?R=93C6EE71-6D40-1014-8BF0-9EFBF894F9D4:en_US



Trivia Challengehttps://github.com/jbrains/trivia


It works well because there are no dependencies

1

1

Serialize game state and compare it with Approval Tests

1

Cover all branches by variying the results of the randomizer

2

2




Server 1Server 2

EncodeAudioLegacy Challenge

Remote Server 1

Audio File

encoding

HTTPS Server 2

Audio File

Encoded Audio File

Audio File available at

Remote Server 1

Encoded Audio File available

download uploadEncode Audio Engine

Server 1Server 2

EncodeAudioLegacy Challenge

Remote Server 1

Audio File

encoding

HTTPS Server 2


Remote Server 1

downloadEncode Audio Engine

upload

AudioAnnouceTmlgURL Remote

Server 1formatfilename

audioConfigTmptarget audio

file extension target

encoding propertieshttpConfigTmpLocal Tempory

Folder path, URL Remote

HTTPS Server 2

Local Tempory Folder

Audio File

Encoded Audio File

Local HTTP Server

Encoded Audio File


AudioFile

name

format

Baby Steps

String comparison with ApprovalTests

Branch coverage by input parameter variation

Serializing a complex type

Mocking web services

Capturing side effects

Step 0: Development environment validation

EclEmmaJUnit

Technical Solution: Unit Testing + Code Coverage Tools

Context: Launch UT + Code Coverage

Server 1

Remote Server 1

Audio File

download

Server 2

encoding

HTTPS Server 2


Remote Server 1

Encode Audio Engineupload




Audio File

Encoded Audio File

Local HTTP Server

Encoded Audio File


AudioFile

name

format

Step 1: Method returns a primitive type

Technical Solution: Approval Tests (string comparison)

Context: No side effect + Method returns a primitive type

Server 1

Remote Server 1

Audio File

download

Server 2

encoding

HTTPS Server 2


Remote Server 1





Audio File

Encoded Audio File

Local HTTP Server

Encoded Audio File


AudioFile

name

format

String

Step 2: Branch coverage by input parameter

variation

Technical Solution: Approval Tests (legacyApprovals)

Context: No side effect + Method returns a primitive type

Server 1

Remote Server 1

Audio File

download

Server 2

encoding

HTTPS Server 2


Remote Server 1





Audio File

Encoded Audio File

Local HTTP Server

Encoded Audio File


AudioFile

name

format

Step 3: Method returns a complex type

Note: encoding + date issues

Context: No side effect + Method returns a complex type

Technical Solution: Approval Tests + XStream

Server 1

Remote Server 1

Audio File

download

Server 2

encoding

HTTPS Server 2


Remote Server 1





Audio File

Encoded Audio File

Local HTTP Server

Encoded Audio File


AudioFile

name

format

Comple

x type

Step 4: Third-party services

Context: WebService difficult to configure or/and not avalaible

Technical Solution: Moco

Server 2

encoding

HTTPS Server 2


Remote Server 1





Audio File

Encoded Audio File

Local HTTP Server

Encoded Audio File


AudioFile

name

format

Server 1

Remote Server 1

Audio File

downloadWeb

Server

Step 5: Capturing side effects

Note:can be used for context with void methodsnot mocking side effect

Context: Side effects

Technical Solution: State, Side Effects Serialization + Approval Tests

Server 2

encoding

HTTPS Server 2


Remote Server 1





Audio File

Encoded Audio File

Local HTTP Server

Encoded Audio File


AudioFile

name

format

Server 1

Remote Server 1

Audio File

download

File

System

state

Pourquoi ça marche?

Pas de rédaction d’assertion

Pas d’effort lié à la maintenance

De bons outils

Tests taillés pour le refactoring

Conclusion

LEGACY CODE

REFACTORING


TESTS

MAINTAINABLE TESTS

http://approvaltests.sourceforge.net/


Ensuite


http://martinsson-johan.blogspot.fr/

http://github.com/dreamhead/moco

https://github.com/pearlfish/pearlfish-javaUI visual diffinghttps://www.youtube.com/watch?v=UMnZiTL0tUcWorking Effectively with Legacy Code – in particular for creating “seams”


http://martinsson-johan.blogspot.fr/

http://github.com/dreamhead/moco

https://github.com/pearlfish/pearlfish-java

https://www.youtube.com/watch?v=UMnZiTL0tUc&feature=youtu.be


Approval Tests only needs 2

lines!



Run your test

Diff Tool (by default TortoiseMerge)

Cf. Using Reporters in Approval Testshttp://blog.approvaltests.com/2011/12/using-reporters-in-approval-tests.html


http://blog.approvaltests.com/2011/12/using-reporters-in-approval-tests.html

http://blog.approvaltests.com/2011/12/using-reporters-in-approval-tests.html


Result of the current testnamed received



Result referencenamed approved



Approve result and save file




Technology

Refactorer du legacy, même pas peur! Agile France