add comment explaining some weirdness
diff --git a/tests/conftest.py b/tests/conftest.py
index fd61803..1cb2b30 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -40,6 +40,8 @@
filtered_backends.append(backend)
if not filtered_backends:
+ # If you pass an empty list to parametrize Bad Things(tm) happen
+ # as of pytest 2.6.4 when the test also has a parametrize decorator
pytest.skip(
"No backends provided supply the interface: {0}".format(
", ".join(iface.__name__ for iface in required_interfaces)