A handfull of the test files with long class names will cause the ZipArchive::extractTo() method to fail, due to the Windows zip file reader saying "Path too long".
This seems to be due to the combination of the long filenames and pathing, on top of the long zip filename being set by either Composer or Github on the download step (I cannot tell which it is), e.g. "6fcfb7666c95f341b42f02c94a47b3a51ed484e0.zip".
The resulting total paths look like this example:
C:\Users\cburgess\AppData\Local\Composer\files\pdepend\pdepend\6fcfb7666c95f341b42f02c94a47b3a51ed484e0\pdepend-pdepend-6fcfb76\src\test\resources\files\Code\ASTMemberPrimaryPrefix\testGraphDereferencedArrayFromStaticMethodCallAndMultipleMethodInvocations.php
It is simply pdepend-1.1.1 that my composer install step is trying to download and install, but the unzip step just can't succeed because of the some of the paths that Windows cannot unzip successfully ("path too long").
I realize it's probably not feasible for you to shorten your class names and path structure. However, no amount of searches I've done leads to anything close to mentioning this issue, so I wanted to make a record of it that people will be able to find.
Bug