specs2 - test with futures, control executing thread

I am using specs2 as my test framework. I want to test a piece of code which is heavily depended on futures.

For example this is the piece of code:

def register(x: Int){
    val f1 = dao1.save(x)
       .map{
         f2 = dao2.save(x)
         f2.onFailure{
            case t => action.revert()      
         }
         f2
       }

    f1.onFailure{
       case t => action.revert()
    }

    f1
}

I want to test the scenario in which dao2.save(x) fails. In this case I expect action.revert() to be executed twice.

The problem is the when I actually test it, while mocking dao2, the assertion occur before the onFailure content get executed. So on my laptop all tests pass, but on the build server(where stuff is a little slower) it fails.

Any good way to handle this case?

Thanks!