add mark that allows us to do skip tests on backends via decorators
diff --git a/tests/conftest.py b/tests/conftest.py
index e059b63..d8ab581 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -4,7 +4,7 @@
     HMACBackend, CipherBackend, HashBackend
 )
 
-from .utils import check_for_iface
+from .utils import check_for_iface, supported_by_backend_skip
 
 
 def pytest_generate_tests(metafunc):
@@ -19,3 +19,4 @@
     check_for_iface("hmac", HMACBackend, item)
     check_for_iface("cipher", CipherBackend, item)
     check_for_iface("hash", HashBackend, item)
+    supported_by_backend_skip(item)