See the Camel testing documentation at
In the bottom there is links about testing existing routes, for example you can use advice with to intercept / replace parts of your routes before testing. For example if you assign an id to your processor, you can replace/remove the processor by the id, using advice with.
See the documentation and examples http://camel.apache.org/advicewith.html and you can look into the unit test source code of camel-core to find more examples.