issue 6275
Add an "exc_value" attribute to the _AssertRaisesContext context manager in the unittest package.  This allows further tests on the exception that was raised after the context manager exits.
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
index 25d792d..a2d4478 100644
--- a/Doc/library/unittest.rst
+++ b/Doc/library/unittest.rst
@@ -888,6 +888,10 @@
          with self.failUnlessRaises(some_error_class):
              do_something()
 
+      The context manager will store the caught exception object in its
+      :attr:`exc_value` attribute.  This can be useful if the intention
+      is to perform additional checks on the exception raised.
+
       .. versionchanged:: 2.7
          Added the ability to use :meth:`assertRaises` as a context manager.