Index: Python-3.3.0/Lib/unittest/mock.py
===================================================================
--- Python-3.3.0.orig/Lib/unittest/mock.py
+++ Python-3.3.0/Lib/unittest/mock.py
@@ -2188,6 +2188,19 @@ def mock_open(mock=None, read_data=''):
     handle.write.return_value = None
     handle.__enter__.return_value = handle
     handle.read.return_value = read_data
+    handle.readline.side_effect = map(lambda x: '{}\n'.format(x), read_data.split('\n'))
+
+    data_as_list = ['{}\n'.format(l) for l in read_data.split('\n')]
+    # If the last line ended in a newline, the list comprehension will have an
+    # extra entry that's just a newline.  Remove this.
+    if data_as_list[-1] == '\n':
+        data_as_list = data_as_list[:-1]
+    else:
+        # if there wasn't an extra newline by itself, then the file being
+        # emulated doesn't have a newline to end the last line  remove the
+        # newline that our naive format() added
+        data_as_list[-1] = data_as_list[-1][:-1]
+    handle.readlines.return_value = data_as_list
 
     mock.return_value = handle
     return mock
Index: Python-3.3.0/Lib/unittest/test/testmock/testwith.py
===================================================================
--- Python-3.3.0.orig/Lib/unittest/test/testmock/testwith.py
+++ Python-3.3.0/Lib/unittest/test/testmock/testwith.py
@@ -171,6 +171,31 @@ class TestMockOpen(unittest.TestCase):
 
         self.assertEqual(result, 'foo')
 
+    def test_readline_data(self):
+        mock = mock_open(read_data='foo\nbar\nbaz\n')
+        with patch('%s.open' % __name__, mock, create=True):
+            h = open('bar')
+            result = h.readline()
+
+        self.assertEqual(result, 'foo\n')
+
+    def test_readlines_data(self):
+        mock = mock_open(read_data='foo\nbar\nbaz\n')
+        with patch('%s.open' % __name__, mock, create=True):
+            h = open('bar')
+            result = h.readlines()
+
+        self.assertEqual(result, ['foo\n', 'bar\n', 'baz\n'])
+
+        # Test that files without a final newline will also be correctly
+        # emulated
+        mock = mock_open(read_data='foo\nbar\nbaz')
+        with patch('%s.open' % __name__, mock, create=True):
+            h = open('bar')
+            result = h.readlines()
+
+        self.assertEqual(result, ['foo\n', 'bar\n', 'baz'])
+
 
 if __name__ == '__main__':
     unittest.main()