Merged in jurko/pytest/break_ExceptionInfo_reference_cycles (pull request #144)

break reference cycles caused by storing local reference to exception info

_pytest/assertion/util.py

@@ -149,11 +149,10 @@ def assertrepr_compare(config, op, left, right):
             if istext(left) and istext(right):
                 explanation = _notin_text(left, right, verbose)
     except Exception:
-        excinfo = py.code.ExceptionInfo()
         explanation = [
             u('(pytest_assertion plugin: representation of details failed.  '
               'Probably an object has a faulty __repr__.)'),
-            u(excinfo)]
+            u(py.code.ExceptionInfo())]
 
     if not explanation:
         return None

_pytest/main.py

@@ -98,6 +98,7 @@ def wrap_session(config, doit):
             if session._testsfailed:
                 session.exitstatus = EXIT_TESTSFAILED
     finally:
+        excinfo = None  # Explicitly break reference cycle.
         session.startdir.chdir()
         if initstate >= 2:
             config.hook.pytest_sessionfinish(

_pytest/python.py

@@ -456,8 +456,8 @@ class Module(pytest.File, PyCollector):
         try:
             mod = self.fspath.pyimport(ensuresyspath=True)
         except SyntaxError:
-            excinfo = py.code.ExceptionInfo()
-            raise self.CollectError(excinfo.getrepr(style="short"))
+            raise self.CollectError(
+                py.code.ExceptionInfo().getrepr(style="short"))
         except self.fspath.ImportMismatchError:
             e = sys.exc_info()[1]
             raise self.CollectError(