strip bound wrappers of class setup/tardown, fixes #140

on python3 im_func is replaced by __func__

_pytest/python.py

@@ -311,12 +311,14 @@ class Class(PyCollectorMixin, pytest.Collector):
         setup_class = getattr(self.obj, 'setup_class', None)
         if setup_class is not None:
             setup_class = getattr(setup_class, 'im_func', setup_class)
+            setup_class = getattr(setup_class, '__func__', setup_class)
             setup_class(self.obj)
 
     def teardown(self):
         teardown_class = getattr(self.obj, 'teardown_class', None)
         if teardown_class is not None:
             teardown_class = getattr(teardown_class, 'im_func', teardown_class)
+            teardown_class = getattr(teardown_class, '__func__', teardown_class)
             teardown_class(self.obj)
 
 class Instance(PyCollectorMixin, pytest.Collector):

testing/test_python.py

@@ -56,6 +56,24 @@ class TestClass:
             "*collected 0*",
         ])
 
+    def test_setup_teardown_class_as_classmethod(self, testdir):
+        testdir.makepyfile("""
+            class TestClassMethod:
+                @classmethod
+                def setup_class(cls):
+                    pass
+                def test_1(self):
+                    pass
+                @classmethod
+                def teardown_class(cls):
+                    pass
+        """)
+        result = testdir.runpytest()
+        result.stdout.fnmatch_lines([
+            "*1 passed*",
+        ])
+
+
 class TestGenerator:
     def test_generative_functions(self, testdir):
         modcol = testdir.getmodulecol("""