Computer system and method automatically generates a test source code for checking validity of an application written in an object oriented language. The application includes objects accessible through an interface implementing programming rules and object behavior rules. For each object, the invention extracts object methods and attributes of the object interface which are impacted by the object behavior rules and extracts the object identification. The invention fills the variable fields of a source code template with the extracted information. The template non variable source code is in conformance with the programming rules and implements a scenario for checking a set of object behavior rules; thus the filled template forms a generated test source code. For distributed applications, the specifications may be EJB or CORBA and the Test Generator uses templates for checking the life-cycle (creation, persistency, removal) of deployed objects.