public void test_addProcessingTime_multiple() {
        DocList docList = new DocList();

        docList.addProcessingTime(10);
        assertEquals(10, docList.getProcessingTime());

        docList.addProcessingTime(20);
        assertEquals(30, docList.getProcessingTime());

        docList.addProcessingTime(5);
        assertEquals(35, docList.getProcessingTime());
    }

    public void test_addContentSize_negative() {

    }

    /**
     * Adds to the total processing time of this document list.
     *
     * @param processingTime the processing time to add in milliseconds
     */
    public void addProcessingTime(final long processingTime) {
        this.processingTime += processingTime;
    }

    /**
     * Returns a string representation of this DocList including metrics and content.
     *

            docList.addContentSize(contentSize);
            final long processingTime = systemHelper.getCurrentTimeAsLong() - startTime;
            docList.addProcessingTime(processingTime);
            if (logger.isDebugEnabled()) {
                logger.debug("Added the document({}, {}ms). The number of a document cache is {}.",

                docList.addContentSize(contentSize);
                final long processingTime = systemHelper.getCurrentTimeAsLong() - startTime;
                docList.addProcessingTime(processingTime);

                if (docList.getContentSize() >= maxDocumentRequestSize || docList.size() >= maxDocumentCacheSize) {
                    indexingHelper.sendDocuments(searchEngineClient, docList);

                    docList.addContentSize(contentSize);
                    final long processingTime = systemHelper.getCurrentTimeAsLong() - startTime;
                    docList.addProcessingTime(processingTime);
                    if (logger.isDebugEnabled()) {
                        logger.debug("Added the document({}, {}ms). The number of a document cache is {} (size: {}).",