Nancy Testing - prevent autoregistration of IApplicationStartup and IRequestStartup

I have a NancyFx app which uses the default bootstrapper. This automatically discovers and registers at startup all classes which implement IApplicationStartup interface and IRequestStartup, respectively.

For unit testing my modules I am using Nancy Testing with the ConfigurableBootstrapper which uses the same conventions as the "production" bootstraper thus making the same automatic discovery and registrations of the above classes.

How can I prevent automatic registration of IApplicationStartup and IRequestStartup assignable classes in unit testing scenarios?