Hi Jack,
I built and ran the tests locally and get exactly the same results as on the farm.
Six junit files generated, `catkin_test_results` reports eight tests with four of them failing.
You see "more" tests than you expect since each grouping level (rostest around a set of rosunit) has to generate its own result file.
Why do the tests fail for me and on the farm but not for you?
After taking a look to the test files of velodyne_height_map it looks like they are using test data which is not available when the dependencies are installed form Debians.
E.g. $(find velodyne_pointcloud)/tests/class.pcap in heightmap_node_hz.test
Your package seems to only download its own testdata but not the other stuff.
Your are likely running the tests locally on top of the dependencies from source for which you have ran the tests before and therefore have the additional test data available.