private Condition doTest(final ExpressionItem expressionItem) {
        // create a noddy term mapper that doesn't need any generated code
        Function<ExpressionTerm, Condition> handler = expressionTerm ->
                DSL.condition(expressionTerm.getField() + "=" + expressionTerm.getValue());

        final CommonExpressionMapper mapper = new CommonExpressionMapper();

        // Set up some noddy term handlers so we can test expression terms
        FIELD_NAMES.forEach(fieldName -> mapper.addHandler(QueryField
                .builder()
                .fldName(fieldName)
                .queryable(true)
                .conditionSet(ConditionSet.DEFAULT_ID)
                .build(), handler));

        final Condition condition = mapper.apply(expressionItem);

        LOGGER.info("expressionItem: {}", expressionItem);
        LOGGER.info("condition: {}", condition);

        return condition;
    }
This ought to behave in a consistent way with ExpressionMatcher
stroom-db-util/src/test/java/stroom/db/util/TestCommonExpressionMapper.java