} else {
                        logger.warn("[{}][{}] Failed to analyze a text(size:{}). {}", field, lang, buf.length(), e.getMessage());
                    }
                }
                buf.setLength(0);
            }
        }
        if (buf.length() > 0) {
            try {

        // Verify messages
        assertEquals("Top level", topLevel.getMessage());
        assertEquals("Level 1", level1.getMessage());
        assertEquals("Level 2", level2.getMessage());
        assertEquals("Level 3 - Root cause", level3.getMessage());
    }

    /**
     * Test serialization
     */
    public void test_serialization() throws Exception {

    /**
     * Constructs a new ExtractException with the specified message and cause.
     *
     * @param message the detail message. The detail message is saved for later retrieval by the {@link #getMessage()} method.
     * @param cause the cause (which is saved for later retrieval by the {@link #getCause()} method).
     *              (A {@code null} value is permitted, and indicates that the cause is nonexistent or unknown.)

    /**
     * Constructs a new {@code CrawlerSystemException} with the specified detail message and cause.
     *
     * @param message the detail message (which is saved for later retrieval by the {@link #getMessage()} method).
     * @param cause the cause (which is saved for later retrieval by the {@link #getCause()} method).
     *              (A {@code null} value is permitted, and indicates that the cause is nonexistent or unknown.)

            if (logger.isInfoEnabled()) {
                final StringBuilder buf = new StringBuilder(100);
                buf.append(e.getMessage());
                if (e.getCause() != null) {
                    buf.append(e.getCause().getMessage());
                }
                logger.info(buf.toString());
            } else if (logger.isDebugEnabled()) {

        if (e.isDebugEnabled()) {
            logger.debug("Crawling Access Exception at {}", urlQueue.getUrl(), e);
        } else if (e.isInfoEnabled()) {
            logger.info(e.getMessage());
        } else if (e.isWarnEnabled()) {
            logger.warn("Crawling Access Exception at " + urlQueue.getUrl(), e);
        } else if (e.isErrorEnabled()) {

                        content = new String(InputStreamUtil.getBytes(entity.getContent()), Constants.UTF_8_CHARSET);
                    } catch (final IOException e) {
                        content = e.getMessage();
                    }
                    logger.warn("Failed to access to {}. The http status is {}.\n{}", tokenUrl, httpStatusCode, content);
                }
            });
        }

        try {
            deferred.promise().getResponse(10, TimeUnit.SECONDS);
            fail();
        } catch (SuggesterException e) {
            assertEquals("An error occurred during the deferred computation.", e.getMessage());
        }
    }

        try {
            errorConverter.init();
            fail("Should throw IOException");
        } catch (IOException e) {
            assertEquals("Init failed", e.getMessage());
        }
    }

    @Test
    public void testConvertWithNormalText() throws IOException {
        // Test convert with normal text
        converter.init();
        String text = "hello world";

                    } catch (final UnsupportedExtractException e) {
                        if (logger.isDebugEnabled()) {
                            logger.debug("{} does not support this data. {}", extractor.getClass().getName(), e.getMessage());
                        }
                    }
                }
                throw new ExtractException("Failed to extract the content using available extractors.");
            }