Lutess is a testing environment designed for synchronous software specified with Lustre, a synchronous data-flow language. It makes possible to automatically generate test input sequences in conformance with a specification of the software external behavior and of guiding directives such as operational profiles and behavioral patterns. Lutess deals with software and specifications involving only boolean inputs and outputs. In this paper we propose an extension of Lutess, using Constraint Logic Programming (CLP), making possible to deal with numeric inputs and outputs. In particular, we define an appropriate execution model for test input generation and show how test data generation according to the main guiding facilities of Lutess can still be performed. Furthermore, operational profile based generation becomes more powerful thanks to the introduction of CLP solvers capabilities which make possible to associate occurrence probabilities to any boolean expression.