Skip time-related assertions on /dev/null

test/ruby/test_file_exhaustive.rb

@@ -1517,9 +1517,12 @@ class TestFileExhaustive < Test::Unit::TestCase
       assert_equal(File.zero?(f), test(?z, f), f)
 
       stat = File.stat(f)
-      assert_equal(stat.atime, File.atime(f), f)
-      assert_equal(stat.ctime, File.ctime(f), f)
-      assert_equal(stat.mtime, File.mtime(f), f)
+      unless stat.chardev?
+        # /dev/null may be accessed by other processes
+        assert_equal(stat.atime, File.atime(f), f)
+        assert_equal(stat.ctime, File.ctime(f), f)
+        assert_equal(stat.mtime, File.mtime(f), f)
+      end
       assert_bool_equal(stat.blockdev?, File.blockdev?(f), f)
       assert_bool_equal(stat.chardev?, File.chardev?(f), f)
       assert_bool_equal(stat.directory?, File.directory?(f), f)