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Software Quality Assurance: Lecture 2. This lecture will cover the following: software defects and related issues; have a good discussion on this topic before jumping directly on to the topic; software defects in six application size ranges; categories of software defects;...
Software Defects - I Lecture # Today’s Lecture Software defects and related issues Have a good discussion on this topic before jumping directly on to the topic What is a Software Defect? A software defect is an error, flaw, mistake, failure, or fault in software that prevents it from behaving as intended (e.g., producing an incorrect or unexpected result) Software defects are also known as software errors or software bugs Effects of Software Defects - Bugs can have a wide variety of effects, with varying levels of inconvenience to the user of the software Some bugs have only a subtle effect on the program’s functionality, and may thus lie undetected for a long time More serious bugs may cause the software to crash or freeze leading to a denial of service Effects of Software Defects - Others qualify as security bugs and might for example enable a malicious user to bypass access controls in order to obtain unauthorized privileges Effects of Software Defects - The results of bugs may be extremely serious In 1996, the European Space Agency’s US $1 billion prototype Arian rocket was destroyed less than a minute after launch, due a bug in the on-board guidance computer program Effects of Software Defects - In June 1994, a Royal Air Force Chinook crashed into the Mull of Kintyre, killing 29 people An investigation uncovered sufficient evidence to convince that it may have been caused by a software bug in the aircraft’s engine control computer Effects of Software Defects - In 2002, a study commissioned by the US Department of Commerce’ National Institute of Standards and Technology concluded that software bugs are so prevalent and detrimental that they cost the US economy and estimated US $59 billion annually, or about 0.6 percent of the gross domestic product Software Defects in Six Application Size Ranges function point or 125 C statements 10 function points or 1,250 C statements 100 function points or 12,500 C statements 1,000 function points or 125,000 C statements 10,000 function points or 1,250,000 C statements 100,000 function points or 12,500,000 C statements Categories of Software Defects Errors of commission Errors of omission Errors of clarity and ambiguity Errors of speed or capacity 10 ... in software that prevents it from behaving as intended (e.g., producing an incorrect or unexpected result) Software defects are also known as software errors or software bugs Effects of Software. .. evidence to convince that it may have been caused by a software bug in the aircraft’s engine control computer Effects of Software Defects - In 20 02, a study commissioned by the US Department of... point or 125 C statements 10 function points or 1 ,25 0 C statements 100 function points or 12, 500 C statements 1,000 function points or 125 ,000 C statements 10,000 function points or 1 ,25 0,000 C