Refining Light-Weight Formal Specifications Validations using Black Box Testing and Code Coverage Analysis: An Electrocardiograph Application

Light-weight formal specifications are used to achieve a better understanding of the desired behavior of a system. The specification must correctly reflect the requirements that were expressed informally to the system being modeled. To validate specifications black-box testing technique had been widely used. Selecting test cases to validate the specification based only on the black-box testing technique makes it possible that we won’t be able to validate the whole formal specification. A complementary technique is code coverage analysis. Combining black-box testing and code coverage analysis will let us evaluate which part of the specification was not validated and thereby to create new test cases. This is reflected in a refined specification, more accurate and correct. As an example we present the light-weight formal specification in VDM++ of a digital electrocardiograph. The specification is based on the informal description of the performance characteristics of the electrocardiograph. Keywords—Software Engineering Design, Formal Methods, Testing, Software Process.