A system of non-regression tests of a designing tool including modules used to build a monitoring device of an aircraft engine is provided. The system includes a processor configured to automatically create an experience base by instrumenting behavior tests upon executing the modules, the experience base including reference input signals, sets of reference parameters, reference output signals, and collections of results of reference executions relating to the modules start again the behavior tests on the modules depending on the corresponding reference input signals and the corresponding sets of reference parameters thus generating test output signals and collections of results of test executions and compare the test output signals with the corresponding reference output signals and the collections of results of test execution with the corresponding collections of results of reference executions in order to test the non-regression of the designing tool.