Disclosed is a method of automatically customizing a computer executable application, such as a test automation harness, based on currently installed modules. The functionality of the application can be split in multiple modules. At runtime, the application can automatically detect the presence or absence of a module. If a module is available, it can automatically be integrated with the application such that the functionality, such as language-level features and constructs, provided by the module is active and/or exposed. If the module is absent, the application can continue executing without the functionality provided by the module.