Cross functional peer review preso 10-01-2013
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Want Higher Quality Software from Your Agile Team?
Cross-Functional Peer Review Works
Mark Hammer
When you create or receive a test plan, who sees it – and how?
Product Mgmt Development Testing
User stories Code Test Plans
Product Mgmt Development
Testing
User storiesCode
Test Plans
Cross-Functional Peer Review
Requirements
Design
Architecture
Discussion
Review
Review
Requirements
Design
Architecture
Code
Discussion
Review
Review
N/A
Where most of the bugs come from
Hapless Developer
Reviewers
Version Control
Types of Code Review
Over-the-Shoulder Email Pair Programming Formal Inspection Meetings Tool
Largest Peer Code Review Study
• Objectives: – lightweight vs. formal inspections– What constitutes an effective review?
• 10-month case study at Cisco• Cisco MeetingPlace product, teleconferencing solution• 3.2 million lines of code• 2500 reviews• 50 developers
60-90 minutes max
Time (minutes)
De
fect
s F
oun
d
Go slow: 200-500 LOC/hour
Defect Density vs. Inspection Rate
0
25
50
75
100
125
150
0 200 400 600 800 1000 1200 1400Review Inspection Rate (LOC/hour)
Def
ect
Den
sity
(d
efec
ts/k
LO
C)
Not too much: 200-400 LOCDefect Density vs. LOC
0
50
100
150
200
0 200 400 600 800 1000
LOC under Review
De
fec
t D
ens
ity
(d
efec
ts/k
LO
C)
Industry Metrics
Measure Industry Average
High Performance Teams
Net Promoter Score 20% > 70%
% defects of total injected found by customer 15% < 2%
% effort spent in finding and fixing defects 50% < 10%
% effort for post-release support 30% < 5%
Unit test code coverage Varies > 80%
Post release defect density 7.5 defects/KLOC
< 0.5 defects/KLOC
Measure Industry Average
High Performance Teams
Net Promoter Score 20% > 70%
% defects of total injected found by customer 15% < 2%
% effort spent in finding and fixing defects 50% < 10%
% effort for post-release support 30% < 5%
Unit test code coverage Varies > 80%
Post release defect density 7.5 defects/KLOC
< 0.5 defects/KLOC
Bugs found in development are 8-12X less expensive to fix than those found in testing phase
And 30-100X less expensive than bugs that reach customers
Case Study: Large National Insurance Company• 2011: 350 developers• 2013: 650 team members• User stories are shared in Word format with entire
team• Design documents are shared in Powerpoint with
entire team• Code is shared with entire team• Test cases are shared in Excel format with entire team
Benefits: Cross-Functional Peer Review• Every member of the extended development team
knows what’s happening• Problems with user stories, code, and test plans are
found faster• Developers are forced to write readable code• Optimization methods/tricks/productive programs
spread faster• Teams can iterate from story to code to test plan• It's Agile• It’s fun
Product Mgmt Development
Testing
User storiesCode
Test Plans
“The simple fact of knowing your work will be reviewed by others means you’ll do it better.”
Mark Hammer
Questions?Comments?
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