Introduction to Inspection

Motivation

• Inspection results at BNR [Russell, IEEE Software, 1991]
  • 2.5 million lines of code inspected
  • On average, one fault found per person-hour invested
  • 2-4 times as effective as testing
  • On average 4.5 person-days to fix a failure reported from the field

• Standard practice at many other companies: IBM, AT&T, Tandem.

• A career skill: at your next interview, mention that you have code inspection skills.

The inspection roles

Moderator

Controls the meetings and ensures conduct is focused and professional.

Reader

Paraphrases the code or documentation.

Recorder

Records any faults found.

Others

Designer, implementor, tester.

The inspection procedure

Overview meeting

Overview of code to be inspected

Individual preparation

Each team member studies the code alone

Inspection meeting

• Reader paraphrases the code
• Other inspectors listen and speak up only if they see a fault
• As soon as a fault is identified and recorded, move on to the next block of code.

Rework

Remove any faults found

Follow-up

Moderator ensures that the rework has been done.
If more than 10% of the code is faulty, run the entire inspection procedure again.

Inspection focus

• Just paraphrasing: what most readers do
  • Frequently there are no detailed, written specifications.
  • So reader paraphrases line-by-line, starting with line 1 and continuing to the end.
  • Other inspectors speak up when they hear something that seems wrong.

• Specialized roles for inspectors
  • To focus on commonly occurring problems, such as: coding conventions, common failures, standard techniques, and portability.
  • In one AT&T inspection team, there was an inspector focused solely on C macros.

CSCI 265 focus

• We do have specifications and so can inspect for "correctness with respect to the specification".

• Correctness of exported functions with respect to the module interface specifications.

• Correctness of local functions with respect to header comments.