Tester, the test-generation component of Reactis, relies on model coverage criteria to construct tests. The tool tracks several coverage criteria as it computes test data, and uses uncovered elements of these criteria to influence subsequent tests that it creates.

With Reactis for C Plugin, Tester measures coverage in the C code as well as in the Simulink and Stateflow portions of a model. The new coverage targets include C statements, as well as decisions,coditions, and MC/DC targets in the C code. The net effect is more comprehensive tests than only tracking coverage targets in the Simulink and Stateflow portions of the model.

Tester employs a patented technique called guided simulation to build tests. Tests in Reactis correspond to simulation runs, with the inputs at each step in a run constituting the input data used for the test. At each step in a simulation run, Tester uses information about uncovered parts of the model and C code to select input data that will advance the coverage of the model.