Application developers may develop applications or portions of application that do not have a corresponding user interface. Testing non-user interface elements of an application may require application developers to develop corresponding user interface elements for all or a portion of the executable code included in the application. Developers may test non-user interface elements of an application or library by wrapping the executable code in a sample application managed by a test harness. The test harness may transmit test operations configured to test the non-user interface elements of the application to the sample application over an inter-process communication channel. The sample application may execute the test and return the results of the test to the test harness using inter-process communication methods.