Skip tests generated by pytest plugins during discovery. (#8242)

For #7287.

news/2 Fixes/7287.md

@@ -0,0 +1,2 @@
+During test discovery, ignore tests generated by pytest plugins (like pep8).
+Tests like that were causing discovery to fail.

pythonFiles/testing_tools/adapter/pytest/_discovery.py

@@ -78,7 +78,8 @@ def pytest_collection_modifyitems(self, session, config, items):
         self._tests.reset()
         for item in items:
             test, parents = self.parse_item(item)
-            self._tests.add_test(test, parents)
+            if test is not None:
+                self._tests.add_test(test, parents)
 
     # This hook is not specified in the docs, so we also provide
     # the "modifyitems" hook just in case.
@@ -92,4 +93,5 @@ def pytest_collection_finish(self, session):
         self._tests.reset()
         for item in items:
             test, parents = self.parse_item(item)
-            self._tests.add_test(test, parents)
+            if test is not None:
+                self._tests.add_test(test, parents)

pythonFiles/testing_tools/adapter/pytest/_pytest_item.py

@@ -152,6 +152,9 @@ def parse_item(item, #*,
     """
     #_debug_item(item, showsummary=True)
     kind, _ = _get_item_kind(item)
+    # Skip plugin generated tests
+    if kind is None:
+        return None, None
     (nodeid, parents, fileid, testfunc, parameterized
      ) = _parse_node_id(item.nodeid, kind)
     # Note: testfunc does not necessarily match item.function.__name__.