Unfortunately, the WORKING_DIRECTORY directive for ADD_TEST seems to be broken as of CMake 2.8.10, fortunately there was a mail thread about this issue in 2.6 so I was able to implement the workaround.
If cmake was able to find Imagination's PVR library, then it'd be nice to make sure that our decompressor matches theirs. We incur a bit of overhead by adding .pvr files into git, but hopefully this cost will be beneficial to actually figuring out how things are working...