Avoid the Zone of Chaos: Economics of Quality and

Productivity via Code ReviewReducing software development risk and cost while improving speed, quality and maintainability by applying review at all levels

Presented by: Joshua GoughAtlanta ALT.NET Meetuphttp://www.meetup/com/AtlAltDotNet6/19/2012

● Avoiding the Ultimate Risk● Software Development Processes● Risks associated with poor code-review

and lack of defect prevention● Automated .NET tools to support

"continuous inspection", code-review, and defect prevention

● Demo of static source-code analysis with Visual Studio and NDepend

Topic Outline

● How to validate that you're building the product your customers or users want and need?

● What untested assumptions and risks can lurk in requirements and design docs?

● What kinds of reviews can happen before or in parallel with coding to test assumptions and mitigate risks?

Avoiding The Ultimate Risk

Danger! Don't Go There!

Say What?

Royce Strawman Waterfall Model

Royce's Observations

Final Royce Model (Shame on our industry for not reading his whole paper)

Generic Iterative and Incremental Model

Boehm Spiral Model

Generic Agile

Extreme Programming (XP) Feedback Loops

Scrum Agile Process Framework

Whirlpool Model(A "violent water metaphor" we can live with and enjoy)

Scrum Agile Process Framework

Let's Review...

Traditional: Known | Known

Agile: Known | Unknown

Lean Startup: Unknown| Unknown

And Now: Code Review...

● Formal code review: involves a careful and detailed process with multiple participants and multiple phases: Example: Fagan Inspection

● Over-the-shoulder : One developer looks over the author's shoulder as the latter walks through the code.

● Email pass-around – Source code management system emails code to reviewers automatically after checkin is made.

● Pair Programming – Two authors develop code together at the same workstation, such is common in Extreme Programming.

● Tool-assisted code review – Authors and reviewers use specialized tools designed for peer code review.

Types of Code Review

Economic Reasons : Defect Cost Increase

Productivity Reasons: Faster Schedule

Relationship between defect rate and development time. As a rule, the projects that achieve the lowest defect rates also achieve the shortest schedules. -- Capers Jones

Sweet Spot!

Cisco Case Study Data : Defect Counts

Formal Code Review

Hope This Guy Gets Lost in Elevator

Email Pass-Around Pre Check-In

Email Pass-Around Post Check-In

Email Pass-Around Code Review(Pray Uncle Bob Doesn't Get The Email, Unless You Crave Discipline!)

Over-The-Shoulder Walkthrough

Don't Be This Guy (Either of Them!)

Pair Programming● Agile software development technique wherein two

programmers work together at one workstation● One drives and writes codes while the other observes

(or navigates) and reviews each line of code● The two programmers switch roles frequently● While reviewing, the observer also considers the

strategic direction of the work in order to:○ Devise ideas for improvements and likely future

problems to address○ Free the driver to focus all of his or her attention on

the "tactical" aspects of completing the current task, using the observer as a safety net and guide

In Other Words...

But, What Does the Science Say?● Isolated studies of pair-programming reveal

results ranging all across the map

● Some meta-analyses also reveal wide-ranging results

● I suspect the answer to be "It depends", therefore proceed without dogma and use pragmatism

Example Study

Study Summary● 48% increase in correctness for complex systems

○ No significant time difference

● Simple systems had 20% time decrease○ No significant correctness difference

● Overall no general time reduction or correctness increase○ But an overall 84% effort increase

● Limitations: this was a one day experiment with 99 individuals and 98 pairs

How would working together longer affect results?

Tool-Assisted Code Review!

Demo: Visual Studio Code Analysis

Demo: NDepend Critical Warnings

11 Lessons from SmartBear Cisco Case Study

1. Review fewer than 200-400 lines of code at a time.

2. Aim for an inspection rate of less than 300-500 LOC/hour

3. Take enough time for a proper, slow review, but not more than 60-90 minutes

Key

4. Authors should annotate source code before the review

Additional Tactical Tips...● 5. Establish quantifiable goals for code

review and capture metrics so you can improve your processes

● 6. Checklists substantially improve results for both authors and reviewers

● 7. Verify that defects are actually fixed!

And Managerial Tips...● 8. Managers must foster a good code review

culture in which finding defects is viewed positively

● 9. Beware the “Big Brother” effect

● 10. The Ego Effect: Do at least some code review, even if you don't have time to review it all

11.Lightweight-style code reviews are efficient, practical, and effective at finding bugs

Many Thanks to SmartBear Software!(See CodeCollaborator Free Trial and Jason Cohen's Free Book)

F r e e !

Contact● Meetup: http://www.meetup.com/AtlAltDotNet● Email: jsgough@gmail.com● Web: http://agilefromthegroundup.blogspot.com