on 06-Nov-2023 (Mon)

为了完善业务逻辑，开发人员必须细致地考虑应用程序所有可能遇到的边界情况，并为这些边界情况设计合适的规则。 当买家单击将商品添加到购物车时，应用程序会向购物车数据库表中添加一个条目，将该用户ID与商品ID关联起来。 虽然一次编写出完美应用程序的可能性微乎其微，但在大多数情况下，开发人员可以从上述的业务逻辑出发，编写出符合业务逻辑的应用程序，并不断测试直到满足用户的需求。 根据业务逻辑设计自动化系统，驱动正常运行的产品和系统，是一个人类认知上的非凡壮举。

The relative probabilities of faults that appear during tests in manufacturing are shown in Figure 11.1. Dynamic faults may be further divided into timing faults (28%) and driver faults (21%). Timing faults and intermittent faults may be due to poor design. It is difficult to design test strategies for such faults.

Static faults are usually modeled by the stuck fault model.

Many physical defects can be modeled as a circuit node being either stuck at 1 (s-a-1) or stuck at 0 (s-a-0).

The single-stuck fault model (SSFM) assumes that a fault directly affects only one node and that the node is stuck at either 0 or 1. These assumptions make test pattern generation easier, but the validity of the model is questionable. Multiple faults do occur, and multiple faults can theoretically mask each other. On the other hand, the model appears to be valid most of the time. Hence, almost all test pattern generation relies on this model. Multiple faults are generally found with test patterns for single faults.