A method includes determining a first quantity of data records of a group of data records from a stream of data records received by an application having a plurality of modules. The method includes, for one or more of the modules of the application, determining a respective second quantity of data records output by the module during processing of the group of data records. The method includes determining whether the first and second quantities of data records satisfy a rule. The rule is indicative of a target relationship among a quantity of data records received by the application and a quantity of data records output by one or more modules of the application.