diff -r 04cc9c32f3e3 Lib/unittest/test/testmock/testwith.py
--- a/Lib/unittest/test/testmock/testwith.py	Thu Jun 12 18:39:42 2014 +0200
+++ b/Lib/unittest/test/testmock/testwith.py	Thu Jun 12 15:01:38 2014 -0400
@@ -180,9 +180,11 @@
             line1 = h.readline()
             line2 = h.readline()
             line3 = h.readline()
+            line4 = h.readline()
         self.assertEqual(line1, 'foo\n')
         self.assertEqual(line2, 'bar\n')
         self.assertEqual(line3, 'baz\n')
+        self.assertEqual(line4, '')
 
         # Check that we properly emulate a file that doesn't end in a newline
         mock = mock_open(read_data='foo')
@@ -192,6 +194,15 @@
         self.assertEqual(result, 'foo')
 
 
+    def test_iter_data(self):
+        # Check that iteration will return all the lines from the fake file
+        mock = mock_open(read_data='foo\nbar\nbaz\n')
+        with patch('%s.open' % __name__, mock, create=True):
+            h = open('bar')
+            lines = list(h)
+        self.assertEqual(lines, ['foo\n', 'bar\n', 'baz\n'])
+
+
     def test_readlines_data(self):
         # Test that emulating a file that ends in a newline character works
         mock = mock_open(read_data='foo\nbar\nbaz\n')