bpo-36366: Return None on stopping unstarted patch object (GH-12472)
Return None after calling unittest.mock.patch.object.stop() regardless of whether the object was started. This makes the method idempotent.
https://bugs.python.org/issue36366
diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index fdde16b..8684f1d 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -1398,7 +1398,7 @@
def __exit__(self, *exc_info):
"""Undo the patch."""
if not _is_started(self):
- raise RuntimeError('stop called on unstarted patcher')
+ return
if self.is_local and self.temp_original is not DEFAULT:
setattr(self.target, self.attribute, self.temp_original)
diff --git a/Lib/unittest/test/testmock/testpatch.py b/Lib/unittest/test/testmock/testpatch.py
index c484adb..2c14360 100644
--- a/Lib/unittest/test/testmock/testpatch.py
+++ b/Lib/unittest/test/testmock/testpatch.py
@@ -772,10 +772,18 @@
def test_stop_without_start(self):
+ # bpo-36366: calling stop without start will return None.
+ patcher = patch(foo_name, 'bar', 3)
+ self.assertIsNone(patcher.stop())
+
+
+ def test_stop_idempotent(self):
+ # bpo-36366: calling stop on an already stopped patch will return None.
patcher = patch(foo_name, 'bar', 3)
- # calling stop without start used to produce a very obscure error
- self.assertRaises(RuntimeError, patcher.stop)
+ patcher.start()
+ patcher.stop()
+ self.assertIsNone(patcher.stop())
def test_patchobject_start_stop(self):
diff --git a/Misc/NEWS.d/next/Library/2019-03-20-15-13-18.bpo-36366.n0eav_.rst b/Misc/NEWS.d/next/Library/2019-03-20-15-13-18.bpo-36366.n0eav_.rst
new file mode 100644
index 0000000..a435048
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-03-20-15-13-18.bpo-36366.n0eav_.rst
@@ -0,0 +1,4 @@
+Calling ``stop()`` on an unstarted or stopped :func:`unittest.mock.patch`
+object will now return `None` instead of raising :exc:`RuntimeError`,
+making the method idempotent.
+Patch byKarthikeyan Singaravelan.