bpo-32933: Implement __iter__ method on mock_open() (GH-5974)

1 files changed, 6 insertions, 3 deletions

diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index db1e642c00..83026e6f3b 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -2358,14 +2358,16 @@ def mock_open(mock=None, read_data=''):
         return type(read_data)().join(_state[0])
 
     def _readline_side_effect():
+        yield from _iter_side_effect()
+        while True:
+            yield type(read_data)()
+
+    def _iter_side_effect():
         if handle.readline.return_value is not None:
             while True:
                 yield handle.readline.return_value
         for line in _state[0]:
             yield line
-        while True:
-            yield type(read_data)()
-
 
     global file_spec
     if file_spec is None:
@@ -2389,6 +2391,7 @@ def mock_open(mock=None, read_data=''):
     _state[1] = _readline_side_effect()
     handle.readline.side_effect = _state[1]
     handle.readlines.side_effect = _readlines_side_effect
+    handle.__iter__.side_effect = _iter_side_effect
 
     def reset_data(*args, **kwargs):
         _state[0] = _iterate_read_data(read_data)