Software Inspections

Defect Removal Efficiency The number of defects found prior to releasing a product divided by The number of defects found prior to release plus the number reported by customers during the first n months of actual use times 100%

Objectives of an Inspection  Find problems at the earliest possible point in the software development process  Ensure that agreement is reached on rework that may need to be done  Verify that any rework done meets predefined criteria

Other Benefits of Inspections  Provide data on product quality and process effectiveness  Build technical knowledge among team members  Increase the effectiveness of software validation testing  Raise the standard of excellence for software engineers

Participants of an Inspection  Moderator – Coordinates the inspection and leads the discussion  Producer – Responsible for the work being inspected  Reader – Paraphrases the work inspected  Inspector – Inspects the product  Recorder – Records problems discussed  Manager – Supervises the producer

Responsibilities of the Moderator  Understand the information being inspected  Lead the team in an effective discussion  Mediate disputes  Recognize key issues and keep the team focused on them  Maintain an unbiased view of the information being presented  Assign responsibilities appropriately

Responsibilities of the Producer  Insure that the work product is ready for inspection  Make required information available on time  Support the moderator in making meeting arrangements, providing copies of materials, and establishing schedules for any required corrective action  Promptly resolve all problems identified  Remain objective and avoid becoming defensive

Responsibilities of the Reader  Be thoroughly familiar with the work product being inspected  Identify logical chunks of information and be able to paraphrase the information in each chunk to allow the moderator to keep the team focused on one chunk at a time  Support the moderator

Responsibilities of the Inspectors  Be thoroughly familiar with the work product being inspected as well as the appropriate documents and standards for the product  Identify discrepancies between the work product and applicable documents and standards  Focus on identifying problems, not solving them  Remain objective  Criticize the product not the producer  Support the moderator

Responsibilities of the Recorder  Be thoroughly familiar with the work product being inspected  Record all issues raised by the team and ensure that they are recorded correctly  Record additional information as requested by the moderator  Support the moderator

Responsibilities of the Manager  Help decide what to inspect  Include inspections in project schedules  Allocate resources for inspections  Support inspection training  Participate in the selection of moderators  Support the moderator in completing any required rework

Attributes of a Good Process (according to SEI)  The process is written  The process is flexible and can be changed  Everyone agrees to follow the process  The process includes metrics, which are used to measure process efficiency  Metrics are the basis for changing the process  The process is actively managed

Institutionalizing Inspections Management Issues  Management must: Understand and support the objectives of the inspection process Be willing to commit the resources necessary to train inspectors Be willing to include inspections in project schedules

Institutionalizing Inspections (Development Process Issues)  There must be: A written software development process or one must be developed Management support for preparing a software development process if it doesn’t already exist A way to modify the process, if necessary, to include inspections at appropriate points Active management of the process

Institutionalizing Inspections (Development Process Issues)  There must be: Support for inspections within the software engineering organization An identification of potential obstacles to the inspection process Resources available to train people in the inspection process and a commitment to train new employees as they are hired

Institutionalizing Inspections (Inspection Metrics)  There must be: A definition of what product and process metrics will be collected form inspections and how this data will be used A continuous improvement process in place that identifies improvements to the inspection process based on collected data

Requirements Inspections “If you can only afford to do one inspection on a project, you will get the biggest return on investment from a requirements inspection. A requirements inspection should be the one inspection that is never skipped.” - Steven R. Rakitin

Why are Requirements Inspections Important?  Requirements are the most common source of problems in the development process  Requirements are written in English by people who typically have little or no training in writing software requirements  The English language is imprecise, ambiguous, and nondeterministic

Attributes of Good Requirements Specifications  Unambiguous  Complete  Verifiable  Consistent  Modifiable  Traceable  Usable

Requirements Inspection Objectives  Make sure each requirement in the Software Requirements Specification (SRS) is consistent and traceable to the document that preceded the SRS  Make sure each requirement in the SRS is clear, concise, internally consistent, unambiguous, and testable

Requirements Inspection Prerequisites  All inspection team members must receive appropriate training  The document(s) that preceded the SRS must have been reviewed and approved  The SRS must have been internally reviewed  A requirements inspection checklist must be available  Guidelines for a good SRS must be available

A Sample Inspection Process  Planning  Overview Meeting (optional)  Preparation  Inspection Meeting  Follow-up

Objectives of Planning  Determine which work products need to be inspected  Determine whether a work product is ready for inspection  Identify the inspection team  Determine whether an overview meeting is necessary  Schedule overview and inspection meetings

Objective of Overview Meeting  Educate the inspection team on the work product being inspected and discuss the review material

Objective of Preparation  To be prepared for the inspection meeting by critically reviewing the review materials and the work product

Objective of the Inspection Meeting  Identify errors and defects in the work product being inspected An error is a problem in which the software or documentation does not meet defined requirements and is found at the point of origin A defect is a problem in which the software or its documentation does not meet defined requirements and is found beyond the point of origin.

Objective of the Follow-Up  Assure that appropriate action has been taken to correct problems found during an inspection