1. A method for testing components of an operating system via a set of application programs in accordance with a test definition, the method comprising: first establishing a set of operating system components to be represented in the test definition; second establishing a set of capabilities of each application program to issue requests to one of the set of operating system components, including for each request a way in which a particular one of the components is accessed; third establishing a set of classes for the components in accordance with various ways in which the application programs access the operating system components; and formulating a set of test calls to be issued by the application programs in accordance with the capabilities defined during the second establishing step, the set of test calls covering the components and classes established during the first establishing and third establishing steps.