    @Test
    void testWithMockBackendProducingHits() {


        DocumentSourceSearcher docSource = new DocumentSourceSearcher();
        Query testQuery = new Query();
        testQuery.setTraceLevel(6);
        testQuery.getModel().getQueryTree().setRoot(new WordItem("drum","album"));

        Result mockResult = new Result(testQuery);
        mockResult.hits().add(new Hit("hit:1", 0.9));
        mockResult.hits().add(new Hit("hit:2", 0.8));
        docSource.addResult(testQuery, mockResult);

        Chain<Searcher> myChain = new Chain<>(new MetalSearcher(), docSource);  // no config to MetalSearcher
        Execution.Context context = Execution.Context.createContextStub();
        Execution execution = new Execution(myChain, context);

        Result result = execution.search(testQuery);
        System.out.println(result.getContext(false).getTrace());

        assertEquals(2, result.hits().size());
    }