A method and system is provided for automated generation of the functional test cases for testing a software system. In an embodiment, the invention provides an expressive decision table (EDT), a requirement specification notation designed to reduce translation efforts. It implements a novel scalable row-guided random algorithm with fuzzing (RGRaF) (pronounced R-graph) to generate test cases. The invention also implements two new coverage criteria targeted at requirements and requirement interactions. The invention also provides fuzzing at time boundaries to achieve scalability. According to an embodiment, the invention also provides the feature of generating error in case the generated functional test case corresponds to system property violation of the software system. According to another embodiment, the system can also reject the functional test case if there is an improbable condition of the software system.