Software Fault: A static defect in the software(i.e.,defect) “缺陷”——Execution
Software Error: An incorrect internal state that is the manifestation of some faults.
”错误的中间状态“——Infection
Software Failure: External, incorrect behavior with respect to the requirements or other description of the expected behavior."失效“——Propagation
PIE Model
- Execution/Reachability：The location or locations in the program that contain the fault must be reached.
- A test may not execute the location of the fault.(控制流调用较为复杂)
- Infection 感染: The state of the program must be incorrect.
- A test executing the fault may not produce an error.(结果相同)
- Propagation 传播: The infected state must propagate to cause some output of the program to be incorrect.
- An error may not be propagated to the output.(结果相同)
例如：
一个程序用for循环求数组和，并且求均值，但i错误的从1开始。——此时对应Fault
当程序运行后，程序将数组第一个数据跳过。——此时对应Error
程序运行结束，输出结果错误。——此时对应Failure
但是，这三种情况有时不会显而易见。
Fault. 当程序复杂时，如果程序没有运行到错误的地方则无法发现Fault。
Error. 按照上例，如数组0 4 5，求和、均值结果正确，并不会产生Error。
Failure. 按照上例，如数组4 3 5，求和发生Error，但均值没有错误，属于No Failure.