how to fail at code reviews in 5 lessons

www.octo.com - www.usievents.com 1@mdomenjoud #NCrafts #CultureCode@mdomenjoud #NCrafts #CultureCode

HOW TO FAIL AT CODE REVIEW

IN FIVE LESSONSMichel DOMENJOUD

www.octo.com - www.usievents.com 2@mdomenjoud #NCrafts #CultureCode

Développeur, in love with code since 2003.

Tech Lead – Coach Craft @OctoTechnology

@mdomenjoud #CultureCode

MICHEL DOMENJOUD


Code review?

Of course we all know about it!


An effective team practice to provide feedback about code quality


Software Craftsmanship : essential practices

+ Continuous integration, Coding standards, Refactoring,

Design, etc.

Feedback

Clean Code AutomatedTesting

Test DrivenDevelopment

Code Review


Proven effective for many years



http://sail.cs.queensu.ca/publications/pubs/msr2014-mcintosh.pdf

http://www.reviewtechnik.de/NationalSoftwareQualityExperiment.pdf

Objective : detect defects early

Up to 65% of detected defects

ROI of 4 to 11h of review → 4h of debug saved

http://sail.cs.queensu.ca/publications/pubs/msr2014-mcintosh.pdf

http://www.reviewtechnik.de/NationalSoftwareQualityExperiment.pdf



Other substantial benefits

Shared coding standards

Reinforce collective code

ownership

Facilitate learning

Improve communication about

code


Peer Review

Pair programmingCollective Review


Fail #1 : We still have bugs everywhere !


Go as fast as you

can !

Do not prepare

anything !

Do not ask how to

do it !

- Take your time, at a sustainable pace

- Ask for code review as soon as possible

- Prepare the review beforehand

- Share coding standards and checklists

- Train together

To miss defects And to detect them ?


Fail #2 My team does not progress


Do not speak to

each other !

Correct the defects

in place of the

author !

Do not write you

coding standards

- Talk with your teammates during reviews

- The author fixes the defects, using pair

programming if necessary

- Write your coding standards down

- Reevaluate them over time

Not to progress And to progress ?


Fail #3 : Reviews look like a wrestling match


Criticize people first

Always start a

debate or language

/ framework war !

To be sure to have a fight

- Criticize the code, not the developer

- Rely on Egoless Programming principles

- This is not the time

- Find compromises

- Pick a standard and write it down

And for a peaceful review ?


Three complementary formats

Peer reviewPair

programming

Start a User Story,

Complex code,

Legacy code, debug,

Learning

Define coding standards

Critical code

New technologies

All the timeOn a

regular basisOn demand

For every code change

Collective

review


5 lessons to be learned for successful reviews

1 – Take your time

Prepare the review beforehand

Sustainable pace (max 1h30 &

300 LoC at a time)

2 – Progress together

Talk with your teammates during

reviews

The author fixes the defects,

using pair programming if

necessary

3 – Use coding standards

Share standards and checklists

Reevaluate them over time

4 – Criticize the code, not the

developer

Egoless Programming principles

5 – Find the format(s) which fit

your team and adapt them.


Culture CodeSoftware Craftsmanship : Better Places with Better Code

A collective book about Software

Craftsmanship’ culture and practices

(in French)

Freely available for download

http://blog.octo.com/tag/software-craftsmanship

http://www.octo.com/fr/publications/20-culture-code