Software Testing and Quality Assurance

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Software Testing and Quality Assurance

• Lecture 26 (a) Testing Interactions (Chapter 6)

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Lecture Outline

• Testing Off-the-Shelf Components
• Protocol Testing
• Testing Patterns
• Testing Exceptions

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Testing off-the-shelf components

• Functionality can be added to an application by
  purchasing Components.
• Quality of components varies from vendor to
  another.
• Acceptance testing for the component in the
  context in which it will be used is necessary.

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Testing off-the-shelf components

• Stress tests extreme, may be correct or
  incorrect values e.g., moving mouse a lot to
  generate a large number of mouse move events,
  making multiple menu selections, etc.

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Protocol testing

• Protocol testing investigates whether the
  implementation of a class satisfies its
  specification
• Protocol sequence of method invocations by
  combining
• A method whose postconditions enable the
  precondition of another method

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Protocol testing

• Each protocol corresponds to a sequence of states
  beginning with
• Initial states of the two objects,
• A sequence of states for each object, and
• Ending with terminal states (denoted in the state
  diagram)
• A test case takes the two objects through one
  complete sequence of methods

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Protocol testing Example

• A protocol can be found by tracing through the
  state diagram.
• This provides a life-cycle test case.
• This provides an effective test of the object in
  the ways that it will interact with its client
  objects.

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Test patterns

• Test patterns are design patterns for test
  software.
• A design pattern captures and reuses design
  knowledge that has gained widespread application
  in the OO software development community,
• e.g., Grid component is based on the Listener
  design pattern

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Test patterns

• A pattern is a specific configuration of
  interactions among a set of objects that form
  some cluster in the overall design.
• For a design pattern there can be a test pattern

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Testing exceptions

• An exception provides an alternative route for
  returning from a method that does not necessary
  move to the next statement after the method is
  invoked.
• Exceptions are powerful
• The exceptional return value is an object and can
  be arbitrary complex.
• The points at which an exception is thrown varies
  based on the depth of the aggregation hierarchy.

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Testing exceptions

• Testing exceptions provide two different
  perspectives
• At the class testing level, the focus is on
  wether each of the method is that class does in
  fact throw the exception.
• Integration testing will determine whether these
  exceptions that are being thrown at the correct
  time are being caught at the correct place.

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Testing Integration at System Level

• Components become so complex that it is easier to
  test them in the context of the application
  itself.
• For example, user interface provided by most
  applications programs is not a single instance of
  some class.

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Key points

• Stress tests extreme, may be correct or
  incorrect values
• Protocol sequence of method invocations by
  combining a method whose post-conditions enable
  the precondition of another method
• A design pattern captures and reuses design
  knowledge that has gained widespread application
  in the OO software development community
• An exception provides an alternative route for
  returning from a method that does not necessary
  move to the next statement after the method is
  invoked.