private String stackTraceIfAny(Result r) {
        if (r.hits().getError() == null) return "";
        if (r.hits().getError().getCause() == null) return "";
        return Arrays.toString(r.hits().getError().getCause().getStackTrace());
    }
Tests where you really test YqlParser but need the full Query infrastructure.

@author steinar
container-search/src/test/java/com/yahoo/search/yql/UserInputTestCase.java