diff -r da0ca7b1351f Lib/unittest/mock.py
--- a/Lib/unittest/mock.py	Thu Jan 29 17:40:59 2015 +0100
+++ b/Lib/unittest/mock.py	Thu Jan 29 19:24:30 2015 +0100
@@ -2309,6 +2309,12 @@
         for line in _data:
             yield line
 
+    def _iter_side_effect():
+        if handle.__iter__.return_value is not None:
+            while True:
+                yield handle.__iter__.return_value
+        for line in _data:
+            yield line
 
     global file_spec
     if file_spec is None:
@@ -2327,10 +2333,14 @@
     handle.read.return_value = None
     handle.readline.return_value = None
     handle.readlines.return_value = None
+    handle.__iter__.return_value = None
+    handle.__next__.return_value = None
 
     handle.read.side_effect = _read_side_effect
     handle.readline.side_effect = _readline_side_effect()
     handle.readlines.side_effect = _readlines_side_effect
+    handle.__next__.side_effect = _iter_side_effect()
+    handle.__iter__.side_effect = _iter_side_effect
 
     mock.return_value = handle
     return mock