private void addChained(Searcher searcher, String sourceName) {
        builder.target(new FederationConfig.Target.Builder().
                id(sourceName).
                searchChain(new FederationConfig.Target.SearchChain.Builder().
                        searchChainId(sourceName).
                        timeoutMillis(10000).
                        useByDefault(true))
        );
        chainRegistry.register(new ComponentId(sourceName),
                createSearchChain(new ComponentId(sourceName), searcher));
    }
Test for federation searcher. The searcher is also tested in
com.yahoo.prelude.searcher.test.BlendingSearcherTestCase.

@author Arne Bergene Fossaa
container-search/src/test/java/com/yahoo/search/federation/FederationSearcherTestCase.java