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Bugs – From Finding to Preventing

Jacky Guo

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About this presentation

•Overview

– Testing vs. Quality Engineering

– Start preventing bugs

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Objectives

• After this presentation, you'll be able to:

– Identify a phased approach for preventing bugs

– Identify two actions for tomorrow to prevent bugs

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Test vs. Quality Engineering (SQE)

"Test: to try something out… in order to find out… how well it works…"

"Engineering: the application of science in the design planning, construction and maintenance of…

manufactured things"

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Test vs. Quality Engineering (SQE) (continued)

Test• Late in the timeline• Reactive• Find defects • Singular in affect

Quality Engineering• First in the timeline• Proactive and

reactive• Understand defects• Multiplicative in affect

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Phased approach

• 3 elements– Clearly written requirements/specs– "Look" at code– "Test" early

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Phase 1: how do I start?• Written requirements– Clarify user& user scenario– Have your design principle

• Simple– One Step instead of two or three– Avoid repeated things – Batch command

• Bug the documents– "Does everyone see the same picture?"– "Will" versus "might, should, desirable"

• Testability/ Sustainability• SMART

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Phase 1: how do I start? (continued)"Look" at Dev Design• Understand dev design

AssumptionDependencyWork flowData flowError/Exception handling/Log system

• Cover different user scenario• Testability• Risk

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Phase 1: how do I start? (continued)"Look" at code• Code inspections or reviews– Reviews are light-weight– Target code subsets– Inspect only the most critical/difficult sections.

• Static analysis– Built into VS2005– Find Bugs

• Compiler warnings• Debugging skill

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Phase 1: how do I start? (continued)

Set the example• Test requirements• Test design– Archive/version control(Testlink)– Reviewed by program manager and developers

• Test code– Small code reviews

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Phase 1: done

Congratulations• You have just grabbed low-hanging fruit• You have prevented countless bugs• You have risen above at least 50% of the Industry

Now what?

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Phase 2: change the process

Learn about your bugs• Find the cause– Unexpected customer requirement?– Vague spec?– Rushed design?– Domain knowledge?– Code error?

• Be gentle, accurate and honest• Make a change

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Phase 2: change the process (continued)

Assess the value/impact of that change• Hard Metrics– Defects per 1K LOC– Test cycles to ship criteria

• Soft Metrics– Less panic at the end– Fewer pizzas ordered– People are happier

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Call to action

• Start small, get a win– What are people most upset about?– What is the low-hanging fruit?– What does the RCA data say?

• Be prepared to set the example

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Call to action (continued)

What can you do tomorrow (pick 1)?• Get a best practice on the schedule• Document one requirement or design– Get it reviewed

• Code-review one critical section• RCA 10 bugs• Implement 10 unit tests

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SUMMARYReview process

•Requirement spec review•Dev Design review•Test Plan review(involve Dev)•Code Review(including bug fix)•Release spec review

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SUMMARYTest case Management

• TC from Bugs by customer/external users• TC from review dev design• TC from user scenario• TC from Bugs review in case of regression• Regression Test strategy("diff" VS "full")• BVT runs before Dev Check in

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SUMMARYBug Management

•Map to TC•Bug quality•Root cause(process may needs change)•Bug fix review to evaluate the risk•Control the bar to fix bug(potential risk)

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