private static void assertParse(String expectedString, String expressionString) throws ParseException {
        DocumentSelector selector = new DocumentSelector(expressionString);
        if (expectedString != null) {
            assertEquals(expectedString, selector.toString());
        }
    }
@author Simon Thoresen Hult
@author bratseth
document/src/test/java/com/yahoo/document/select/DocumentSelectorTestCase.java