private Execution createExecution(Searcher searcher) {
        return new Execution(chainedAsSearchChain(searcher), Execution.Context.createContextStub());
    }
Tests creating a set of rule bases (the same set as in inheritingrules) from config

@author bratseth
container-search/src/test/java/com/yahoo/prelude/semantics/test/ConfigurationTestCase.java