A white box testing method tests public interfaces within a component of a software system. A setup function is executed to configure a nested public interface within the component to raise an exception. Initialization code is executed that calls the setup function. Test code is executed that calls the component and that evaluates how the component handles the exception raised by the nested public interface. Code is executed within the nested public interface to determine whether the setup function has been called and to raise the exception in response to an affirmative determination.