Software Testing

Software Testing

1. Testing Purposes

   • Ensure design requirements/specifications are met
     • ensures user safety depending on software (medical, space engineering etc)
       • Improve analysis skills and growth as a programmer
   • Measures the quality of the software (metrics)
   • Find and correct bugs
   • Importance
     • Reduces development costs
       • Bug fixes post-release cost 40-100 times more than during early development
         • Customer loyalty
           • word of mouth market share
             • Reduced cost for end users
               • Ensures intended behaviour

2. Role of an OS in a computer system

   • What is an OS?
     • Software that controls the allocation and usage of hardware resources
       • Memory
       • CPU time
       • Disk Space
       • Peripheral devices
   • What is a Device Driver?
     • Allows a computer system to communicate with a device
   • What is a network?
     • A group of computers and associated devices that are connected by communications facilities.

3. Measuring Software Quality

   • Metrics
     • 'Standards of measurement' Measure of quantifiable or countable software characteristics.
     • Performance Metrics
       • Time taken to complete a process
         • Amount of space required by the application
     • Reliability Metrics
       • Total number of bugs - DEFECT DENSITY
         • This is the number of bugs divided by the number of lines of code.
     • Related to four functions of management
       • Planning
         • Organization
           • Control
             • Improvement
     • Benefits
       • Quantifiable characteristics are malleable and therefore fixable?

4. Benefits to Users

   • Lowered costs
     • Usability
       • Reliability
         • No need to ID bugs: waste time
           • No downtime for bug fixes
             • Less training and user support if software behaves expectedly
               • User Satisfcation