Merge pull request python-trio#12 from altendky/curio_requires_3_6

Only test Curio on 3.6+

Author: njsmith

sniffio/_tests/test_sniffio.py

@@ -1,3 +1,5 @@
+import sys
+
 import pytest
 
 from .. import (
@@ -43,6 +45,7 @@ async def this_is_asyncio():
         current_async_library()
 
 
+@pytest.mark.skipif(sys.version_info < (3, 6), reason='Curio requires 3.6+')
 def test_curio():
     import curio