Fix memory leak with pytest.raises by using weakref

AUTHORS

@@ -97,6 +97,7 @@ mbyt
 Michael Aquilina
 Michael Birtwell
 Michael Droettboom
+Michael Seifert
 Mike Lundy
 Nicolas Delaby
 Oleg Pidsadnyi

CHANGELOG.rst

@@ -9,6 +9,9 @@
 * When loading plugins, import errors which contain non-ascii messages are now properly handled in Python 2 (`#1998`_).
   Thanks `@nicoddemus`_ for the PR.
 
+* Fixed memory leak in the RaisesContext (pytest.raises) (`#1965`_).
+  Thanks `@MSeifert04`_ for the report the PR.
+
 *
 
 
@@ -81,7 +84,7 @@
   enabled. This allows proper post mortem debugging for all applications
   which have significant logic in their tearDown machinery (`#1890`_). Thanks
   `@mbyt`_ for the PR.
-  
+
 * Fix use of deprecated ``getfuncargvalue`` method in the internal doctest plugin.
   Thanks `@ViviCoder`_ for the report (`#1898`_).
 
@@ -378,7 +381,7 @@ time or change existing behaviors in order to make them less surprising/more use
 
 * Refined logic for determining the ``rootdir``, considering only valid
   paths which fixes a number of issues: `#1594`_, `#1435`_ and `#1471`_.
-  Updated the documentation according to current behavior. Thanks to 
+  Updated the documentation according to current behavior. Thanks to
   `@blueyed`_, `@davehunt`_ and `@matthiasha`_ for the PR.
 
 * Always include full assertion explanation. The previous behaviour was hiding

_pytest/_code/code.py

@@ -1,6 +1,7 @@
 import sys
 from inspect import CO_VARARGS, CO_VARKEYWORDS
 import re
+from weakref import ref
 
 import py
 builtin_repr = repr
@@ -230,7 +231,7 @@ def ishidden(self):
                 return False
 
         if py.builtin.callable(tbh):
-            return tbh(self._excinfo)
+            return tbh(None if self._excinfo is None else self._excinfo())
         else:
             return tbh
 
@@ -370,7 +371,7 @@ def __init__(self, tup=None, exprinfo=None):
         #: the exception type name
         self.typename = self.type.__name__
         #: the exception traceback (_pytest._code.Traceback instance)
-        self.traceback = _pytest._code.Traceback(self.tb, excinfo=self)
+        self.traceback = _pytest._code.Traceback(self.tb, excinfo=ref(self))
 
     def __repr__(self):
         return "<ExceptionInfo %s tblen=%d>" % (self.typename, len(self.traceback))