Software Inspections

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Software Inspections

• PROFIT course

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What will we cover?

• Inspection process overview
• Initiating the inspection process
• The inspection process
• Checking
• Termination
• Follow-up activities

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Inspection

• ANSI/IEEE Std. 729-1983
• Inspection is... a formal evaluation technique
  in which software requirements, design or code
  are examined in detail by a person or a group
  other than the author to detect faults, violation
  of development standards, and other problems

The purpose of the inspection is to detect faults
in order to improve the quality of the product
and process.
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Inspection process overview
Changerequests
Product document
Process improvements
Loggingmeeting
Walk-through
Edit and follow-up
Individualchecking
Kick-off
5
The inspection process - part 1

• Walk-through
• Request for inspection
• Planning the inspection
• Documents needed
• The entry process
• Kick-off meeting

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The inspection process - part 1
Changerequests
Product document
Process improvements
Rules,checklists,procedures
Loggingmeeting
Walk-through
Edit and follow-up
Individualchecking
Kick-off
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Walk-through - 1

• Used early in the lifecycle of a document. Focus
  is on
• Presenting the chosen solution to peers.
• Obtaining feedback, such as
• Alternative solutions
• Other peoples experiences

The goal of a walk-through is to obtain consensus
on the solution
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Walk-through - 2

• The purpose of a walk-through is to make sure
  that the chosen solution is sound.
• The walk-through as it is used here does not
  require a finished document.
• What is required is a clear idea of how the
  author is planning to solve the problem at hand.

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Walk-through - 3

• The author decides when to have the walk-through.
• Since its main purpose is to collect ideas and
  obtain consensus, it is wise to have the
  walk-through before the author has sunk so much
  effort into the solution that he can not change
  it.

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Initiating the inspection process

• The inspection process starts with a request for
  inspection from the author to the person
  responsible for inspections in the company.
• The person responsible appoints an inspection
  leader.
• First step is always to check that the document
  is fit for inspection.

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Request for inspection - 1

• The author should decide when the document is
  ready for inspection.
• The person responsible for the inspection will
  appoint an inspection leader.
• The choice of leader is important for the success
  of the inspection.

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Request for inspection - 2

• The inspection leader
• Will lead the inspection process. Thus, he must
  have proper training.
• Should not be a manager. If this can not be
  avoided, he should at least not be the manager of
  the author(s).

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Request for inspection - 3

• The inspection leaders first job is to check
  that the document delivered to inspection holds
  sufficient quality.
• This is important in order not to
• Humiliate the author
• Waste the time of the inspection participants

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Planning the inspection - 1

• The following activities must be performed before
  the inspection can start
• Who shall participate in the inspection.
• Who have time available for preparation and
  meetings?
• Who has the necessary knowledge concerning
  application, language, tools, methods?
• Identify and obtain all relevant documents
• The document to be inspection
• Relevant background material - why is this
  document produced?
• Applicable standards and checklists.

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Planning the inspection - 2

• Identify roles in the inspection process
  according to expertise.
• Split the inspection up into two or more
  inspections if
• The document is too big,
• More than five persons are needed - for instance
  due to the need for application expertise

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Planning the inspection - 3

• No inspection meeting should take more than two
  hours.
• Define necessary preparation time.
• Make a meeting schedule - in co-operation with
  the inspection participants. Make sure everybody
  adhere to this schedule. This depends on
• Who should participate?
• When can we have the necessary documentation?
• When are the other relevant deadlines?

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Documents needed

• The following documents must be available
• The document to be inspected.
• All documents needed to understand the document
  to be inspected and why this particular solution
  was chosen.
• Rules, standards and checklists applicable to
• The document to be inspected.
• The process that produced the document.
• The inspection process.

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The entry process - 1

• This process tries to avoid inspection of
  documents that are not ready for this process.
• The inspection leader should make sure that the
  document has a minimum quality level.
• It is practical to have a set of simple
  requirements that the document must meet.

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The entry process - 2

• Some rules from Gilb
• All source documents are
• Available in writing.
• Have been inspected and accepted.
• The document to be inspected has been
• Presented in an earlier walk-through.
• Checked by all applicable tools - e.g. a compiler.

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The entry process - 3

• The most important is that the document, in the
  inspection leaders opinion
• Has no obvious errors. These should always be
  fixed before inspection.
• Will have a fair chance of being accepted.
• Otherwise, we are wasting the time of a lot of
  persons

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Kick-off meeting - 1

• Give a short introduction to the document to be
  inspected.
• Decide on who will check which aspect(s). This
  will allow each participant to contribute most
  efficiently.
• Hand out all relevant material - document to be
  inspected, source documents, checklists etc.

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Kick-off meeting - 2

• Agree on the process of the inspection, such as
  meeting schedule, checklists to be used,
  inspection strategy and grading of issues.
• Set targets for resources.
• Sum up available experiences from the latest
  inspections. Examples
• Important - efficient - checklist questions.
• Average number of issues per page.
• Average number of pages per hour during
  preparations.

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The inspection process - part 2

• Individual checking - how can we assure maximum
  benefits from each inspection participant
• The logging meeting
• Documenting the inspection results.
• Identifying new issues based on group
  discussions.

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The inspection process - part 2
Changerequests
Product document
Planning
Process improvements
Rules,checklists,procedures
Loggingmeeting
Walk-through
Edit and follow-up
Individualchecking
Kick-off
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Individual checking - 1

• This is the main activity of the inspection. Each
  participant read the document to look for
• Potential errors - inconsistencies with
  requirements or common application experience
• Lack of adherence to company standards or good
  workmanship

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Individual checking - 2

• Important rules for each participant
• Focus according to the assigned role in the
  inspection process.
• Adhere to the time allotted to individual
  inspection.
• Finish in time for the logging meeting.
• Use the distributed checklists.

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Individual checking - 3

• Mark all issues in the inspected document.
• An issue does not have to be something you know
  is an error - it can also be something you need
  to get clarified.
• Grade all issues, for instance as minor or major.

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The logging meeting - 1

• The logging meeting has three purposes
• Record all issues raised by the participants.
• Use the group discussion following the issues
  raised, to find and log new issues.
• Record questions and improvement suggestions to
  the document author(s).

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The logging meeting - Guidelines - 1

• Avoid activities like
• Long explanations.
• Defending your opinions.
• Asking for long clarifications.
• Do not start discussions on whether something is
  really wrong. It is sufficient that one
  participant think that something is wrong.

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The logging meeting - Guidelines - 2

• Do not start discussions on solutions to issues
  raised - the meeting focus is on identifying
  issues.
• Make sure all issues are logged, together with
  their severity. It is important that each issue
  is described in such a way that it is easy to
  identify for the author(s).

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The inspection Process - part 3
Changerequests
Product document
Planning
Process improvements
Rules,checklists,procedures
Loggingmeeting
Walk-through
Edit and follow-up
Individualchecking
Kick-off
32
The inspection Process - part 3

• Completion
• Edit the documents. This is the responsibility
  of the authors.
• Follow-up.Check that all issues are resolved.
• Exit.Based on documented exit criteria

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Edit the documents - 1

• The author must go through the inspection meeting
  log and address all issues. This will result in
  one of the following
• Correction of a fault.
• Insertion of new text to avoid further
  misunderstandings.
• Send change requests to authors of other
  documents.

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Edit the documents - 2

• Send improvement suggestions to owners of
  checklists, standards etc.
• Each issue dealt with should be ticked off in the
  log. If necessary, add comments.
• Insight gained during editing which results in
  identification of improvement possibilities
  should be sent to the owners of the relevant
  standards, rules or checklists.

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Follow-up activities

• It is usually not possible for the inspection
  leader to control that all issues have been
  settled in a satisfactory manner. What he can do
  is to check that all
• Issues have been ticked off.
• All improvement suggestions have been sent to the
  appropriate person.

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Exit - 1

• Rules of thumb
• The number of errors left after edit is equal to
  the number of errors found during inspections.
• One sixth of all corrections will fail or
  introduce a new error in the document.
• These rules give us a rough idea of the error
  content of the document after inspections and
  corrections. If we have defined a limit for this,
  we can decide whether we need a document rewrite
  or not.

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Exit - 2

• Gilb has suggested a list of exit criteria. Here
  are some examples
• The inspection participants have used at least
  the recommended number of person-hours for
  preparations.
• All editing is completed.
• The estimate for errors remaining is less than
  0.25 per page.
• Author and inspection leader agree that the
  document in general has sufficient quality.

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Exit - 3

• If the document does not meet the exit criteria
  we should do one of the following
• Make a major rewrite
• Write the document from scratch - throw away the
  document and start anew.
• Repeat the inspection. This is only useful if the
  reason for not meeting the exit criteria lies in
  the way the inspection was performed - for
  instance too little preparation time used.

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The inspection process - part 4
Changerequests
Product document
Planning
Process improvements
Rules,checklists,procedures
Loggingmeeting
Walk-through
Edit and follow-up
Individualchecking
Kick-off
40
Process improvement - 1

• The main purpose of the inspection is to find
  errors. However, in order avoid doing the same
  errors over and over again, we need to look into
• Why was the errors inserted into the document?
• Why didnt the author discover these errors
  himself?
• What can we do to prevent the same problems for
  the next document?
• A meeting to improve the process should be
  arranged after the logging meeting but with the
  same persons.

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Process improvement - 2

• The following three steps are recommended
• Identify the most important identified errors or
  issues. This can for instance be based on
  frequency or cost.
• Have a brainstorming session on possible causes
  for errors. Causes can be technical,
  organisational, political or others.
• Assign improvement suggestions to the most
  important causes.
• The log of the improvement meeting is handed over
  to the personnel responsible for improvement
  actions.

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Process improvement - 3

• Some advises for the improvement meeting
• Each issue is given a short presentation.
• Brainstorm possible causes. Focus on root causes.
• Brainstorm improvement suggestions.
• The improvement meeting should have about the
  same duration as the logging meeting.
• Each of the first three steps should be short.
  Gilb suggests one minute but this might be too
  short.