Post on 12-Apr-2017
Tackling legacy codeMaking scary code less scary
Tangled Fishing Line - Aristocrats-hat https://flic.kr/p/6qdTC1 CC BY 2.0
Tomas MalmstenSoftware Craftsman @tomasmalmsten
http://www.tomasmalmsten.com public@tomasmalmsten.com
Founder of
@oescg
Programmer at
Øresund SoftwareCraftsmanship Group
What?
“Any code I didn’t write”
“Any code not covered by test”
“Any code older then n years”
“Any code that is hard to understand”
“Legacy code is all production code which scares you when you have to change it.”
“All code required to deliver the business capability of the system ”
Production code?
Why?
Fix problems
Introduce new features
Achieve
1. What do we want to achieve?
2. Where do we start?
3. What is this code doing anyway?
4. How can I keep safe?
5. Next steps
Ambition Level
Achieve
Where do we start then?
Start where you stand
.
Where do we start?
Leaning - Tom Parkinson - https://flic.kr/p/6esPpL - CC BY 2.0
Where do we start?
Offender profiling
Where do we start?
Prague Photographic Hotspot - Steven Kay - https://flic.kr/p/9e4vHH - CC BY-SA 2.0
Temporal Coupling
Where do we start?
What is this code doing anyway?
From IOCCC 2013 winners cable3 - 8086tiny by Adrian Cable
Specification tests
Understanding code
Design - Ben Brown - https://flic.kr/p/8aK8Wh - CC BY-SA 2.0
From The Cucumber for Java Book by Seb Rose, Matt Wynne, Aslak Hellesøy
Tooling
Cucumber
SpecFlow
RSpec
Selenium support
KarmaJS
but basically any BDD tool works
Conversational Scrutiny
Understanding code
Jennifer Drawing Ideas - Juhan Sonin - https://flic.kr/p/juPL2q - CC BY 2.0
Telling the story of the system
Understanding code
Understanding code
C4 Architecture Diagrams
Context
Container
Component
Class
Understanding code
The Golden Master
NeXTSTEP 3.3 Gamma (Golden Master) - Gerben Wierda- https://flic.kr/p/7rF8jj - CC BY-SA 2.0
How to proceed
Light the Forest
How to proceed
Find the seams
How to proceed
Code from: https://github.com/sandromancuso/trip-service-kata
Break dependencies
How to proceed
Tama Leaver - https://flic.kr/p/dXgorH - CC BY 2.0The Enterprise Dependency - http://thedailywtf.com/articles/The-Enterprise-Dependency
Name everything
How to proceed
Next steps
Find out what the team knows
Domain
Languages
Testing
Automation
Frameworks
Next steps
Start small
Small changes
Small tests
Small incremental learning
Next steps
Employ continuous learning
Daily standup with a learning focus
Coder dojos
Mob programming
Pair programming
Retrospective
Next steps
SummaryLegacy code = All production code which scares you when you have to change it.
Why
Ambition level
Where to start
Where you stand
Hotspot Analysis
Temporal Coupling Analysis
Summary
How to understand
Specification Tests
Conversational Scrutiny
Telling the story of the system
C4 Architecture Diagrams
Summary
How to proceed
Golden Master
Light the Forest
Find the seams
Break dependencies
Name everything
Next steps
What does the team know
Start small
Optimise for learning
Tomas Malmsten@tomasmalmsten
http://www.tomasmalmsten.com public@tomasmalmsten.com
http://www.slideshare.net/TomasMalmsten/tackling-legacy-code-november-2015
Øresund SoftwareCraftsmanship Group
@oescg
http://www.efolder.net