tests: Assert for /proc being a mountpoint for cross-fs tests

Skip cross-fs tests if /proc is not a mountpoint. This handles cases
when /proc exists but is not mounted which is quite normal
e.g. on Gentoo/FreeBSD.

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/test_find_top_level.py b/tests/test_find_top_level.py
index a326384..17f83c4 100644
--- a/tests/test_find_top_level.py
+++ b/tests/test_find_top_level.py
@@ -159,8 +159,8 @@ class TestCrossDevice(TempDirTestCase):
     }
 
     def setUp(self):
-        if not os.path.exists('/proc'):
-            raise unittest.SkipTest('/proc does not exist')
+        if not os.path.ismount('/proc'):
+            raise unittest.SkipTest('/proc is not a mountpoint')
         super(TestCrossDevice, self).setUp()
         os.symlink('/proc', os.path.join(self.dir, 'test'))