1 Software Testing and Quality Assurance Lecture 10 - The Testing Perspective (Chapter 2, A Practical Guide to Testing Object-Oriented Software)

2 Lecture Outline Testing perspective Object-Oriented Concepts Object Message Interface

3 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.

4 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.

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

6 Object Oriented Concepts - Testing Perspective OO programming is centered around Object Message Interface Class Inheritance Polymorphism

7 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.

8 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.

9 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.

10 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.

11 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.

12 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).

13 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

14 Key points Testing perspective: a way of looking at any development product and questioning its validity. Testing perspective is: Skeptical, Objective, Thorough; and Systematic.