RELAY is a model of faults and failures that defines failure conditions, which describe test data for which execution will guarantee that a fault originates erroneous behavior that also transfers through computations and information flow until a failure is revealed. This model of fault detection provides a framework within which other testing criteria's capabilities can be evaluated. In this paper, we analyze three test data selection criteria that attempt to detect faults in six fault classes. This analysis shows that none of these criteria is capable of guaranteeing detection for these fault classes and points out two major weaknesses of these criteria. The first weakness is that the criteria do not consider the potential unsatisfiability of their rules; each criterion includes rules that are sufficient to cause potential failures for some fault classes, yet when such rules are unsatisfiable, many faults may remain undetected. Their second weakness is failure to integrate their proposed rules; although a criterion may cause a subexpression to take on an erroneous value, there is no effort made to guarantee that the intermediate values cause observable, erroneous behavior. This paper shows how the RELAY model overcomes these weaknesses.

Fault-based testing focuses on the detection of particular classes of faults. RELAY is a fault-based testing technique whose model resembles a relay race. Analysis has shown that RELAY overcomes the weaknesses of other fault-based testing techniques.

RELAY defines revealing conditions that guarantee that a fault originates an error during execution and that the error transfers through computations and data flow until a failure is revealed. This model of error detection provides a fault-based criterion for test data selection. The model is applied by choosing a fault classification, instantiating the conditions for the classes of faults, and evaluating them for the program being tested. Such an application guarantees the detection of errors caused by any fault of the chosen classes. As a formal model of error detection, RELAY provides the basis for an automated testing tool. This paper presents the concepts behind RELAY, discusses how RELAY could be used as the foundation for a testing system, and compares RELAY to other fault-based testing techniques.

RELAY, a model for error detection, defines revealing conditions that guarantee that a fault originates an error during execution and that the error transfers through computations and data flow until it is revealed. This model of error detection provides a framework within which the capabilities of other testing criteria can be evaluated. In this paper, we analyze three test data selection criteria that attempt to detect faults in six fault classes. This analysis shows that none of these criteria is capable of guaranteeing error detection for these fault classes and points out two major weaknesses of these criteria. The first weakness is that the criteria do not consider the potential unsatisfiability of their rules; each criterion includes rules that are sufficient to cause errors for some fault classes, yet when such rules are unsatisfiable, many errors may remain undetected. Their second weakness is failure to integrate their proposed rules; although a criterion may cause a subexpression to take on an erroneous value, there is no effort made to guarantee that the enclosing expression evaluates incorrectly. This paper shows how the test data selection criterion defined by RELAY overcomes these weaknesses.

RELAY, a model for error detection, defines revealing conditions that guarantee that a fault originates an error during execution and that the error transfers through computations and data flow until it is revealed. This model of error detection provides a fault-based criterion for test data selection. The model is applied by choosing a fault classification, instantiating the conditions for the classes of faults, and applying them to the program being tested. Such an application guarantees the detection of errors caused by any fault of the chosen classes. As a formal mode of error detection, RELAY provides the basis for an automated testing tool. This paper presents the concepts behind RELAY, describes why it is better than other fault-based testing criteria, and discusses how RELAY could be used as the foundation for a testing system.