Software Testing and Quality Assurance

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Software Testing and Quality Assurance

• Lecture 17 - Test Analysis Design Models
  (Chapter 4, A Practical Guide to Testing
  Object-Oriented Software)

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Lecture Outline

• Evaluation Criteria Organization of the guided
  inspection activities.
• Preparing for the guided inspection.

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Guided inspection evaluation criteria

• Correctness is a measure of the accuracy of the
  model
• In analysis it is the accuracy of the problem
  description.
• In design it is how accurately the model
  represents the solution of the problem
• The model is correct with respect to a set of
  test cases if every test case produces the
  expected result.

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Guided inspection evaluation criteria

• Completeness is a measure of the inclusiveness
  of the model (are any necessary, or at least
  useful, elements missing from the model)?
• In iterative incremental process, completeness is
  considered relative to how mature the current
  increment is expected to be.
• Do all objects needed for the sequence diagram
  come from classes in the class diagram?
• The model is complete if the result of executing
  the test cases can be adequately represented
  using only the content of the model.

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Guided inspection evaluation criteria (cont...)

• Consistency is a measure of whether there are
  contradictions within the model or between the
  current model and the model upon which it is
  based.
• Consistency can determine whether there are
  contradictions or conflicts present either
  internal to a single diagram or between two
  diagrams.
• The model is inconsistent if there are different
  representations within the model for similar test
  cases.

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Guided inspection evaluation criteria (cont...)

• Other qualities like performance goals define a
  number of system attributes that the development
  team might wish to verify.
• The guided inspection test cases can be used as
  scenarios for testing performance.

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Organization of the guided inspection activity

• Basic roles
• Domain expert the source of the expected results
• Tester conduct the analysis necessary to select
  effective test cases.
• Developer the creators of the models under test.
• Individual inspections testers complete a
  checklist specific to the type of model being
  inspected.
• This process can be automated.

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Preparing for the guided inspection specifying
the inspection

• Scope of an inspection is defined by specifying a
  set of use cases, a set of packages, or abstract
  classes/interfaces.
• Depth of an inspection is defined by specifying
  layers in aggregation hierarchies under which
  messages are not sent.

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Preparing for the guided inspection realistic
models

• Layered approach more individual diagrams but
  each diagram is sufficiently modular to fit
  within the scope of a specific inspection

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Preparing for the guided inspection realistic
models layered approach
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Preparing for the guided inspection realistic
models layered approach (cont)
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Preparing for the guided inspection selecting
test cases for the inspection

• Test cases can be selected to ensure that
  specific types of coverage are achieved or to
  find specific type of defects.

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Preparing for the guided inspection selecting
test cases for the inspection

• Test case selection methods
• Orthogonal defect classification most likely to
  identify defects by covering the different
  categories of system actions that trigger
  defects.
• Use profiles give confidence in the reliability
  of the product by identifying which parts of the
  program are used the most,
• Risk Analysis

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Preparing for the guided inspection selecting
test cases for the inspection (cont...)

• Orthogonal defect classification (ODC)
• The activities that caused a defect to be
  detected are classified as triggers.
• The guided inspection technique uses several of
  these triggers as a guide to select test cases.

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Preparing for the guided inspection selecting
test cases for the inspection (cont...)

• By structuring the guided inspection process so
  that
• as many of these triggers as possible are
  encountered,
• you ensure that the tests that guide the
  inspection are more likely to trigger as many
  failures as possible.

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Preparing for the guided inspection selecting
test cases for the inspection (cont...)

• Use profiles
• A use profile for a system is an ordering of the
  individual test cases based on a combination of
  the frequency and criticality values for the
  individual use cases.

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Preparing for the guided inspection selecting
test cases for the inspection (cont...)

• Risk as a test case selector
• Risk can be used as the basis for test case
  selection
• It is useful during the development
• It is not appropriate after development when we
  are trying to achieve some measure of reliability
  of the software,
• at that time the use of profile technique is
  better because it supports the way software will
  be used.

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Preparing for the guided inspection creating
test cases

• Use case scenario the path taken
• The alternative paths several scenarios that
  differ from the use scenario but represent valid
  execution
• Exceptional paths scenarios that result in error
  conditions

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Preparing for the guided inspection an example
of a use case

• Use case 1
• Actor Player
• Use Scenario The user selects the play option
  from the menu. The system responds by starting
  the game.
• Alternate Paths If a match is already in
  progress, the selection is ignored.
• Exceptional Cases If the match cannot open the
  display, an error message is displayed and the
  game aborts.
• Frequency Low
• Criticality High
• Risk Medium

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Testing specific types of models

• The level of detail in the model becomes greater
  as development proceeds.
• The amount of information also increases as
  development proceeds.
• The exact interpretation of the evaluation
  criteria can be made more specific for a specific
  model.
• The membership of the inspection team changes for
  different models.

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Key points

• Evaluation criteria
• Correctness
• Completeness
• Consistency
• Other qualities
• Test case selection methods
• Orthogonal defect classification
• Use profiles
• Risk

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Announcement

• Homework 1
• December 14, 2008 (5 PM)
• Quiz 3
• Wednesday November 19, 2008