Methods, computing systems and computer program products implement embodiments of the present invention that include defining multiple data fabrication rules, each of the data fabrication rules including a fabrication time and a data operation. a simulation of a software application is initiated, the simulation including a sequence of simulation times, and upon detecting, during the simulation, one or more first given fabrication rules having respective fabrication times matching one or more first simulation times, fabricated data is generated in response to performing the respective data operation of each of the detected one or more first given fabrication rules. Upon detecting, during the simulation, a second given fabrication rule whose fabrication time matches a second simulation time subsequent to the one or more first simulation times, the data operation of the second given fabrication rule is performed on a subset of the fabricated data.