assertRaises as context manager now allows you to access exception as documented

Lib/test/test_unittest.py

@@ -3059,8 +3059,13 @@ class Test_Assertions(TestCase):
             pass
         else:
             self.fail("assertRaises() didn't let exception pass through")
-        with self.assertRaises(KeyError):
-            raise KeyError
+        with self.assertRaises(KeyError) as cm:
+            try:
+                raise KeyError
+            except Exception, e:
+                raise
+        self.assertIs(cm.exception, e)
+
         with self.assertRaises(KeyError):
             raise KeyError("key")
         try:

Lib/unittest/case.py

@@ -91,7 +91,7 @@ class _AssertRaisesContext(object):
         self.expected_regexp = expected_regexp
 
     def __enter__(self):
-        pass
+        return self
 
     def __exit__(self, exc_type, exc_value, tb):
         if exc_type is None: