The story of tools, process and cajoling that we've done to improve quality code—both automated and cultural changes we've done. A recent project (Mr. Clean) automates code quality tasks in Atlassian Stash.

1. ZILLOW | TRULIA | STREETEASY | HOTPADS

2. CLEAN ALL THE THINGS!
ENCOURAGING CLEAN CODE IN BIG TEAMS
Dave Rochwerger, Engineering Director, Agent Platform
@catchdave
ZILLOW | TRULIA | STREETEASY | HOTPADS

3. ZILLOW | TRULIA | STREETEASY | HOTPADS
Zillow Group
• Culture is paramount
• Many teams, many offices
(SF office > 200 engineers)
• Up to 100 engineers contribute to a repository
• Many products, release cycles & techs

4. Clean Code

5. ZILLOW | TRULIA | STREETEASY | HOTPADS
Clean Code
• Low defects
• Maintainable
• Testable

6. Clean code in large companies?

8. ZILLOW | TRULIA | STREETEASY | HOTPADS
2014: The Bad
• Too many bugs
• Highly coupled, low communication teams
• Preventable mistakes (code quality & releasing)
• Inconsistent testing knowledge & usage

9. ZILLOW | TRULIA | STREETEASY | HOTPADS
2014: The Good
• Company-wide training
• Code quality guidelines
• IDE plugins
• Git hooks
• Post-merge CI jobs

10. ZILLOW | TRULIA | STREETEASY | HOTPADS

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Mr. Clean
Encouraging high code quality

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Mr. Clean Goals
1. Push defect detection as early as possible
2. Make it difficult to contribute bad code
3. Make it easy to contribute good code
• Automate away easy things
• Code review focus should be subjective
Design' Coding' QA' Post/release'
Effort'

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“Culture eats strategy for breakfast”

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Blocks Merging

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Stash Integration

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Jenkins Integration

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Approach
• Lots of testing
• Kept goals in sight
• Iterate, iterate, iterate
• Garner constant feedback
• Stealth deployment (nothing like testing in prod)
• Communicate, communicate, communicate

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Results (so far)
• 15,000 PRs examined since May
• Bugs were found on day 1
• Test suites 100% usable
• Many “saved my life” anecdotes

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Results (so far)
Bugs per week down 30%
0"
2"
4"
6"
8"
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1" 2" 3" 4" 5" 6" 7" 8" 9" 10"11"12"13"14"15"16"17"18"19"20"21"22"23"24"25"26"27"28"29"30"31"32"33"34"35"36"37"38"39"40"41"42"43"44"
Bugs%found%
Week%Number,%2015%
Team%A%Bugs%
Team"A" Expon."(Team"A)"
Mr."Clean""

21. The Future

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Insights Reporting

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Take-aways
• Clean code is important
• Clean code is harder in large teams
• Fostering the right culture is key
• Spread the word about your great work!

24. ZILLOW | TRULIA | STREETEASY | HOTPADS
Questions?
Dave Rochwerger
@catchdave
ZILLOW | TRULIA | STREETEASY | HOTPADS