Software Testing: Concepts and Operations

4 Software Specifications

The specification of a software product is a description of the functional requirements that the product must satisfy. It is not common to study software specifications in the context of software testing; we do so in this book for a variety of reasons, which are as follows:

• Specifications are the Basis for Test Oracles: As we discuss in Chapter 3, the design of a test oracle is a critical step in software testing; this step consists primarily in selecting a specification against which we test the program and in implementing it. This step plays an important role in determining the effectiveness of the test.
• Testing and Relative Correctness: We cannot talk about testing without talking about faults (testing means exposing, identifying, and/or removing faults); and we cannot talk about faults without talking about relative correctness (a program from which we have removed a fault is more correct, in some sense, than the original faulty program); and we cannot talk about relative correctness without talking about correctness (as correctness is the ultimate form of relative correctness); and we cannot talk about correctness without talking about specifications (correctness is relative to a specification).
• A Bridge Between Testing and Verification: It is customary to argue that dynamic testing and static verification are complementary techniques to ensure the correctness or reliability of software products. But complementarity is meaningful only if ...