private void assertGrouping(String expected, List<VespaGroupingStep> steps) {
        List<String> actual = new ArrayList<>(steps.size());
        for (VespaGroupingStep step : steps) {
            actual.add(step.continuations().toString() +
                    step.getOperation());
        }
        assertEquals(expected, actual.toString());
    }
Tests Query.Select

@author henrhoi
@author bratseth
container-search/src/test/java/com/yahoo/select/SelectTestCase.java