Although testing is central to debugging and software certification, there is no adequate language to specify test suites over source code. Such a language should be simple and concise in daily use, feature a precise semantics, and of course, it has to facilitate suitable engines to compute test suites and assess the coverage achieved by a test suite. This paper introduces the language FQL designed to fit these purposes. We achieve the necessary expressive power by a natural extension of

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... expressions which matches test suites rather than individual executions. To evaluate the language, we show for a list of informal requirements how to express them in FQL. Moreover, we present a test case generation engine for C programs and perform practical experiments with the sample specifications. General Terms Languages, Verification • Coverage Evaluation. We can determine coverage with respect to an FQL query achieved by other test methods, e.g., directed, model-based, or manual testing. A clear understanding of coverage enables us to combine existing testing techniques in a precise manner. For instance, we can use concise specifications of missing test cases as inputs for a heavy-weight tool such as a model checker. An interface with our tool to perform automated coverage completion is part of current work. • Systematic Reasoning about Test Specifications. Finally, we believe that FQL gives us a clean and simple framework to