A method for automatically generating test programs includes receiving a description of a system under test, expressed in terms of variables associated with the system and conditional constraints including semantics applied to the variables, and receiving a definition of an event to be tested in the system. The method generates an ECondCSP over the variables responsively to the definition of the event and to the conditional constraints, such that at least some of the semantics of the conditional constraints are preserved in the ECondCSP when one or more of the variables to which the semantics are applied are inactive. The ECondCSP is solved to generate a test case for the system.