As described in section 11.5: “Verifying the Configuration” PDFUnit provides a test to check that all required libraries and files can be found in the classpath:

<comment>
  This tests verifies that all required libraries and files are found.
  Additionally it logs some system properties and writes 
  everything into both an XML file and an HTML formatted file.
</comment>

<testcase name="verifyRequiredFilesAndLibraries">
  <verifyInstallation verificationFile="verifyInstallation.vip"/>
</testcase>

The result is written into an HTML file whose name is part of the error message: