w/ the fix from JDK-8249700 to make the test doing its thing on mac, the test fails on '/dev' mount point:
SecurityManager = null
<...>
/dev:
  df total= 216064 free = 0 usable = 0
  getX total= 216576 free = 0 usable = 0
<...>
SecurityManager = GetXSpace$Allow
/dev:
  df total= 216064 free = 0 usable = 0
  getX total= 216576 free = 0 usable = 0
<...>
1 test(s) failed
STDERR:
FAILED: '/dev': 216064 != 216576
FAILED: '/dev': 216064 != 216576
Exception in thread "main" java.lang.RuntimeException: 156 tests: 2 failure(s), first
at GetXSpace.main(GetXSpace.java:386)
Caused by: java.lang.RuntimeException: '/dev': 216064 != 216576
at GetXSpace.setFirst(GetXSpace.java:102)
at GetXSpace.fail(GetXSpace.java:87)
at GetXSpace.compare(GetXSpace.java:227)
at GetXSpace.testDF(GetXSpace.java:370)
at GetXSpace.main(GetXSpace.java:382)