PDFUnit comes with the utility ExtractBookmarks which exports bookmarks from PDF documents into an XML file. Chapter 3.4: “Bookmarks and Named Destinations” describes how to use this created XML file for bookmark tests.

::
:: Extract bookmarks from a PDF document into an XML file
::

@echo off
setlocal
set CLASSPATH=./lib/pdfunit-2015.10/*;%CLASSPATH%
set CLASSPATH=./lib/itext-5.5.1/*;%CLASSPATH%
set CLASSPATH=./lib/bouncycastle-jdk15on-150/*;%CLASSPATH%

set TOOL=com.pdfunit.tools.ExtractBookmarks
set OUT_DIR=./tmp
set IN_FILE=diverseContentOnMultiplePages.pdf
set PASSWD=

java  %TOOL%  %IN_FILE%  %OUT_DIR%  %PASSWD%
endlocal

The file diverseContentOnMultiplePages.pdf contains 4 bookmarks:

The output file _bookmarks_diverseContentOnMultiplePages.out.xml can be used for XML-based tests:

<?xml version="1.0" encoding="UTF-8"?>
<Bookmark>
  <Title Action="GoTo" Page="1 XYZ 56.7 745 0" >Content on first page.</Title>
  <Title Action="GoTo" Page="2 XYZ 56.7 745 0" >Content on page 2.</Title>
  <Title Action="GoTo" Page="3 XYZ 56.7 733.5 0" >Content on page 3.</Title>
  <Title Action="GoTo" Page="4 XYZ 56.7 733.5 0" >Content on last page.</Title>
</Bookmark>

Internally, PDFUnit uses the method SimpleBookmark.getBookmark(PdfReader) from iText. Many thanks to the developers of iText.