// Verify different message codes
        assertEquals(unknownErrorCode, unknownException.getMessageCode());
        assertEquals(parseErrorCode, parseException.getMessageCode());
        assertNotSame(unknownException.getMessageCode(), parseException.getMessageCode());
    }

    @Test
    public void test_complexMessageCode() {

        // Verify
        assertEquals(loginErrorCode, loginException.getMessageCode());
        assertEquals(logoutErrorCode, logoutException.getMessageCode());
        assertNotSame(loginException.getMessageCode(), logoutException.getMessageCode());
    }

    @Test
    public void test_complexMessageCode() {

        } catch (final InvalidQueryException e) {
            if (logger.isDebugEnabled()) {
                logger.debug("Invalid query: {}", form.q, e);
            }
            throwValidationError(e.getMessageCode(), this::asListHtml);
        } catch (final ResultOffsetExceededException e) {
            if (logger.isDebugEnabled()) {
                logger.debug("Invalid offset: {}", form.offset, e);
            }