Software Testing and Quality Assurance

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Software Testing and Quality Assurance

• Lecture 10 - The Testing Perspective (Chapter 2,
  A Practical Guide to Testing Object-Oriented
  Software)

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Lecture Outline

• Testing perspective
• Object-Oriented Concepts
• Object
• Message
• Interface

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Testing Perspective

• A way of looking at any development product and
  questioning its validity.
• Person examining work products from this
  perspective utilizes
• A thorough investigation of the software and
• All its representations to identify faults.

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Testing Perspective

• Requires that a piece of software demonstrate
  that
• It not only performs according to is
  specification, but
• Performs only to that specification.

A product is tested to determine that it will do
what it is supposed to do, and it is also tested
to ensure that it does not do what it is not
supposed to do.
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Testing Perspective

• Skeptical
• Wants proof of quality
• Objective
• Makes no assumptions
• Thorough
• Does not miss important areas
• Systematic
• Searches are reproducible

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Object Oriented Concepts - Testing Perspective

• OO programming is centered around
• Object
• Message
• Interface
• Class
• Inheritance
• Polymorphism

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Object Oriented Concepts - Testing Perspective

• There are wide range of meanings for these
  concepts. For example,
• Distinction between operations and methods is not
  significant for most programmers.

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Object Oriented Concepts - Testing Perspective

• The distinction is significant to tester because
• the approach to testing an operation, which is
  part of class specification and a way to
  manipulate an object,
• is somewhat different from testing a method,
  which is a piece of code that implements an
  operation.

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Object - Testing Perspective

• An object is an operational entity that
  encapsulates both specific data values and code
  that manipulates those values. For example,
• The data about a specific bank account and the
  operations needed to manipulate that data form an
  object.

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Object - Testing Perspective

• Objects are the direct target of the testing
  process during software development.
• The life cycle for an object begins when it is
  created, proceeds through a series of status, and
  ends when the object is destroyed.

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Object - Testing Perspective

• An object encapsulates and hides information.
• An object has a state that persists for the life
  of the object.
• Testers care about
• Whether the object behaves according to its
  specification.
• Whether it interacts appropriately with
  collaborating objects in an executing program.

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Message- Testing Perspective

• A message is a request that an operation be
  performed by some object.
• OO is a community of objects that collaborative
  by sending messages to one another.
• A message has a sender (originating a message).
• A message has a receiver (receiving the message).

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Message- Testing Perspective

• A message may include actual parameters.
• Some messages result in some form of reply such
  as return value and exception.
• Testers care about
• Senders
• Receivers
• Parameters

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Key points

• Testing perspective a way of looking at any
  development product and questioning its validity.
• Testing perspective is
• Skeptical,
• Objective,
• Thorough and
• Systematic.