A computer-implemented method to validate generated test cases after changes to a test model, the method comprising: receiving an old test model for an old system; generating a test suite comprising a plurality of test cases for the old test model using a test generator, wherein the plurality of test cases are generated by traversing portions of a finite state machine that represents the old test model; receiving a new test model for a new system that represents a new version of the old system; validating, using a trace analyzer, the structure of each of the plurality of test cases resulting in a list of remaining test cases from the test suite, wherein the vertices and edges in each of the test cases are compared to vertices and edges in the new test model, wherein if the vertices in a given one of the test cases are found in the new test model and the edges in the given test case are the same as in the new test model, then said test case is deemed to be structurally supported in the new test model; and processing, at a model generator, each of the test cases in the list to create a corresponding set of manipulated test models (602', 604') by using the new test model as a starting point, wherein for each of the test cases the new test model is modified based on the structure of the given test case by: creating a copy of the new test model; removing all edges in the new test model which are not contained in the given test case; and copying and inserting edges and vertices that are traversed more than once, in order to obtain the same test sequence as in the given test case; and triggering the test generator for each of the manipulated test models (602', 604'), wherein if the result from the test generator is a test suite that is generated from the given manipulated test model (602', 604'), designating the corresponding test case as being a valid test case for the new test model, wherein when the test generator is invoked for the given manipulated test model (602', 604') to generate the test suite, the test generator incorporates initialization data that is associated with the given test case so that where there is initialization data, the test generator generates the test suite if the test suite can be executed with the original data configuration of the test case from which the manipulated test model (602', 604') was created and if the test generator does not produce a test suite, designating the corresponding test case as not being a valid test case for the new test model. receiving an old test model for an old system; generating a test suite comprising a plurality of test cases for the old test model using a test generator, wherein the plurality of test cases are generated by traversing portions of a finite state machine that represents the old test model; receiving a new test model for a new system that represents a new version of the old system; validating, using a trace analyzer, the structure of each of the plurality of test cases resulting in a list of remaining test cases from the test suite, wherein the vertices and edges in each of the test cases are compared to vertices and edges in the new test model, wherein if the vertices in a given one of the test cases are found in the new test model and the edges in the given test case are the same as in the new test model, then said test case is deemed to be structurally supported in the new test model; and processing, at a model generator, each of the test cases in the list to create a corresponding set of manipulated test models (602', 604') by using the new test model as a starting point, wherein for each of the test cases the new test model is modified based on the structure of the given test case by: creating a copy of the new test model; removing all edges in the new test model which are not contained in the given test case; and copying and inserting edges and vertices that are traversed more than creating a copy of the new test model; removing all edges in the new test model which are not contained in the given test case; and copying and inserting edges and vertices that are traversed more than once, in order to obtain the same test sequence as in the given test case; and triggering the test generator for each of the manipulated test models (602', 604'), wherein if the result from the test generator is a test suite that is generated from the given manipulated test model (602', 604'), designating the corresponding test case as being a valid test case for the new test model, wherein when the test generator is invoked for the given manipulated test model (602', 604') to generate the test suite, the test generator incorporates initialization data that is associated with the given test case so that where there is initialization data, the test generator generates the test suite if the test suite can be executed with the original data configuration of the test case from which the manipulated test model (602', 604') was created and if the test generator does not produce a test suite, designating the corresponding test case as not being a valid test case for the new test model.