Issue #3187: Add sys.setfilesystemencoding.
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index b5b5077..5c1a8e9 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -658,6 +658,11 @@
         # sys.flags
         check(sys.flags, size(vh) + self.P * len(sys.flags))
 
+    def test_setfilesystemencoding(self):
+        old = sys.getfilesystemencoding()
+        sys.setfilesystemencoding("iso-8859-1")
+        self.assertEqual(sys.getfilesystemencoding(), "iso-8859-1")
+        sys.setfilesystemencoding(old)
 
 def test_main():
     test.support.run_unittest(SysModuleTest, SizeofTest)