@Test
    void error_when_no_document_or_search_chain() {
        List<ResolveResult> results = resolve("document4");
        assertEquals("Could not resolve source ref 'document4'.", results.get(0).errorMsg());
    }
Test for SourceRefResolver.

@author Tony Vaagenes
container-search/src/test/java/com/yahoo/search/federation/sourceref/SourceRefResolverTestCase.java