Many statechart-based testing strategies result in specifying a set of paths to be executed through a (flattened) statechart. These techniques can usually be easily automated so that the tester does not have to go through the tedious procedure of deriving paths manually to comply with a coverage criterion. The next step is then to take each test path individually and derive test data, i.e., fully specified test cases. This requires that we determine the system state required for each event/transition that is part of the path to be tested and the input parameter values for all events and actions on the transitions. We propose here a methodology to automate this procedure, which is based on a careful normalization and analysis of event/action contracts and transition guards written with the Object Constraint Language (OCL). It is illustrated by a case study that exemplifies the steps and provides an initial validation. Though many of the steps are automated, some inputs are still required from the modeler and tester and further work is necessary to push the automation even further and solve a number of remaining issues. This paper is a first attempt at clarifying the issues and identifying the analysis steps required in such an endeavor.