Issue #26807: mock_open 'files' no longer error on readline at end of file.

Patch from Yolanda Robla.

2 files changed, 14 insertions, 0 deletions

diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 7400fb7..123c156 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -2341,6 +2341,8 @@ def mock_open(mock=None, read_data=''):
                 yield handle.readline.return_value
         for line in _state[0]:
             yield line
+        while True:
+            yield type(read_data)()
 
 
     global file_spec
diff --git a/Lib/unittest/test/testmock/testmock.py b/Lib/unittest/test/testmock/testmock.py
index 526eeab..9910ab9 100644
--- a/Lib/unittest/test/testmock/testmock.py
+++ b/Lib/unittest/test/testmock/testmock.py
@@ -1440,6 +1440,18 @@ class MockTest(unittest.TestCase):
         self.assertEqual('abc', first)
         self.assertEqual('abc', second)
 
+    def test_mock_open_after_eof(self):
+        # read, readline and readlines should work after end of file.
+        _open = mock.mock_open(read_data='foo')
+        h = _open('bar')
+        h.read()
+        self.assertEqual('', h.read())
+        self.assertEqual('', h.read())
+        self.assertEqual('', h.readline())
+        self.assertEqual('', h.readline())
+        self.assertEqual([], h.readlines())
+        self.assertEqual([], h.readlines())
+
     def test_mock_parents(self):
         for Klass in Mock, MagicMock:
             m = Klass()