Don't crash when inferring nodes from with statements, with multiple context managers. Closes #18.

3 files changed, 16 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index a1b9aab0..f2a60cb2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,10 @@ Change log for the astroid package (used to be astng)
     * Make sure that objects returned for namedtuple
       inference have parents.
 
+    * Don't crash when inferring nodes from `with` clauses
+      with multiple context managers. Closes #18.
+      
+
 2013-10-18  --  1.0.1
     * fix py3k/windows installation issue (issue #4)
 
diff --git a/protocols.py b/protocols.py
index a26986cb..e66b802c 100644
--- a/protocols.py
+++ b/protocols.py
@@ -311,6 +311,8 @@ nodes.ExceptHandler.assigned_stmts = raise_if_nothing_infered(excepthandler_assi
 def with_assigned_stmts(self, node, context=None, asspath=None):
     if asspath is None:
         for _, vars in self.items:
+            if vars is None:
+                continue
             for lst in vars.infer(context):
                 if isinstance(lst, (nodes.Tuple, nodes.List)):
                     for item in lst.nodes:
diff --git a/test/unittest_regrtest.py b/test/unittest_regrtest.py
index de97e019..265fc14a 100644
--- a/test/unittest_regrtest.py
+++ b/test/unittest_regrtest.py
@@ -144,6 +144,16 @@ multiply(1, 2, 3)
         self.assertEqual(default.name, 'x')
         self.assertEqual(next(default.infer()).value, True)
 
+    def test_with_infer_assnames(self):
+        builder = AstroidBuilder()
+        data = """
+with open('a.txt') as stream, open('b.txt'):
+    stream.read()
+"""
+        astroid = builder.string_build(data, __name__, __file__)
+        # Used to crash due to the fact that the second
+        # context manager didn't use an assignment name.
+        list(astroid.nodes_of_class(nodes.CallFunc))[-1].infered()
 
 class Whatever(object):
     a = property(lambda x: x, lambda x: x)