10.1 Basic definitions A failure is an unacceptable behaviour exhibited by a system The frequency of failures measures the reliability -An important design objective is to achieve a very low failure rate and hence high reliability -a failure can result from a violation of an explicit or implicit requirement a defect is a flaw in any aspect of the system that contributes, or may potentially contribute, to the occurrence of one or more failures lt might take several defects to cause a particular failure An error is a slip-up or inappropriate decision by a software developer that leads to the introduction of a defect www.oseng.cor C Lethbridge/Laganiere 2001 Chapter 10: Testing and Inspecting for High Quality 2© Lethbridge/Laganière 2001 Chapter 10: Testing and Inspecting for High Quality 2 10.1 Basic definitions • A failure is an unacceptable behaviour exhibited by a system —The frequency of failures measures the reliability —An important design objective is to achieve a very low failure rate and hence high reliability. —A failure can result from a violation of an explicit or implicit requirement • A defect is a flaw in any aspect of the system that contributes, or may potentially contribute, to the occurrence of one or more failures —It might take several defects to cause a particular failure • An error is a slip-up or inappropriate decision by a software developer that leads to the introduction of a defect