add a test id to the multi mark

Author: RonnyPfannschmidt

conftest.py

@@ -6,4 +6,5 @@ def pytest_generate_tests(metafunc):
     assert len(multi.kwargs) == 1
     for name, l in multi.kwargs.items():
         for val in l:
-            metafunc.addcall(funcargs={name: val})
+            metafunc.addcall(id='%s_%s' %(name, val),
+                             funcargs={name: val})