Refactorer du legacy, même pas peur! Agile France

Refactorer legacy, même
pas peur!
Johan MARTINSSON
Développeur - Indépendant
martinsson.johan@gmail.co
m
@johan_alps
Rémy SANLAVILLE
Développeur - Orange Software
Expert
remy.sanlaville@orange.com
@sanlaville

Working with Legacy Code
Refactoring Legacy Code with Object
Calisthenics2012 - 2013
Anonymous Developers - Season 1

100% Legacy Code Coverage with Golden
Master2014
Anonymous Developers - Season 2

Le problème – dans le legacy
Long d’écrire les tests
Les tests haut niveau sont longs à éxécuter
Les tests unitiare adhèrent au code

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 game
using a randomizer
for correct and wrong answers
How long do you need to
reach ~100% code coverage ?

Trivia Challenge
https://github.com/jbrains/trivia
http://www.hasbro.com/games/en_US/shop/details.cfm?R=93C6EE71-
6D40-1014-8BF0-9EFBF894F9D4:en_US
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 1
Server 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 upload
Encode Audio Engine

Server 1
Server 2
EncodeAudioLegacy Challenge
Remote Server 1
Audio File encoding
HTTPS Server 2
at Remote Server 1
download
Encode Audio Engine
upload
AudioAnnouceTmlg
URL Remote
Server 1
format
filename
audioConfigTmp
target audio file
extension
target encoding
propertieshttpConfigTmp
Local Tempory
Folder path,
URL Remote
HTTPS Server 2
Local Tempory Folder
Audio File Encoded
Audio File
Local HTTP
Server
Encoded
Audio File
Encoded Audio File
available
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
at Remote Server 1
Encode Audio Engine
upload
AudioAnnouceTmlg
URL Remote
Server 1
format
filename
Audio File Encoded
Audio File
Local HTTP
Server
Encoded
Audio File
Encoded Audio File
available
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
at Remote Server 1
Encode Audio Engine
upload
AudioAnnouceTmlg
URL Remote
Server 1
format
filename
Audio File Encoded
Audio File
Local HTTP
Server
Encoded
Audio File
Encoded Audio File
available
AudioFile
name
format

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
at Remote Server 1
Encode Audio Engine
upload
AudioAnnouceTmlg
URL Remote
Server 1
format
filename
Audio File Encoded
Audio File
Local HTTP
Server
Encoded
Audio File
Encoded Audio File
available
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
at Remote Server 1
Encode Audio Engine
upload
AudioAnnouceTmlg
URL Remote
Server 1
format
filename
Audio File Encoded
Audio File
Local HTTP
Server
Encoded
Audio File
Encoded Audio File
available
AudioFile
name
format

Step 4: Third-party services
Context: WebService difficult to configure or/and not
avalaible
Technical Solution: Moco
Server 2
encoding
HTTPS Server 2
at Remote Server 1
Encode Audio Engine
upload
AudioAnnouceTmlg
URL Remote
Server 1
format
filename
Audio File Encoded
Audio File
Local HTTP
Server
Encoded
Audio File
Encoded Audio File
available
AudioFile
name
format
Server 1
Remote Server 1
Audio File
download

Step 5: Capturing side effects
Note: can be used for context with void methods
not mocking side effect
Context: Side effects
Technical Solution: State, Side Effects Serialization + Approval
Tests
Server 2
encoding
HTTPS Server 2
at Remote Server 1
Encode Audio Engine
upload
AudioAnnouceTmlg
URL Remote
Server 1
format
filename
Audio File Encoded
Audio File
Local HTTP
Server
Encoded
Audio File
Encoded Audio File
available
AudioFile
name
format
Server 1
Remote Server 1
Audio File
download

Pourquoi ça marche?
Pas de rédaction d’assertion
Pas d’effort lié à la maintenance
De bons outils
Tests taillés pour le refactoring

http://approvaltests.sourceforge.net/

Ensuite
http://martinsson-johan.blogspot.fr/
http://github.com/dreamhead/moco
https://github.com/pearlfish/pearlfish-java
UI visual diffing
https://www.youtube.com/watch?v=UMnZiTL0tUc
Working Effectively with Legacy Code – in particular for
creating “seams”

Approval Tests
only needs 2
lines!

Run your test
Diff Tool (by default TortoiseMerge)
Cf. Using Reporters in Approval Tests
http://blog.approvaltests.com/2011/12/using-reporters-in-approval-tests.html

Result of the current test
named received

Result reference
named approved

Approve result
and save file

Refactorer du legacy, même pas peur! Agile France

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Refactorer du legacy, même pas peur! Agile France