diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/library/unittest.mock.rst | 35 |
1 files changed, 28 insertions, 7 deletions
diff --git a/Doc/library/unittest.mock.rst b/Doc/library/unittest.mock.rst index bfab00e..c011e54 100644 --- a/Doc/library/unittest.mock.rst +++ b/Doc/library/unittest.mock.rst @@ -1119,13 +1119,13 @@ patch Instead of ``autospec=True`` you can pass ``autospec=some_object`` to use an arbitrary object as the spec instead of the one being replaced. - By default :func:`patch` will fail to replace attributes that don't exist. If - you pass in ``create=True``, and the attribute doesn't exist, patch will - create the attribute for you when the patched function is called, and - delete it again afterwards. This is useful for writing tests against - attributes that your production code creates at runtime. It is off by - default because it can be dangerous. With it switched on you can write - passing tests against APIs that don't actually exist! + By default :func:`patch` will fail to replace attributes that don't exist. + If you pass in ``create=True``, and the attribute doesn't exist, patch will + create the attribute for you when the patched function is called, and delete + it again after the patched function has exited. This is useful for writing + tests against attributes that your production code creates at runtime. It is + off by default because it can be dangerous. With it switched on you can + write passing tests against APIs that don't actually exist! .. note:: @@ -1247,6 +1247,27 @@ into a :func:`patch` call using ``**``:: ... KeyError +By default, attempting to patch a function in a module (or a method or an +attribute in a class) that does not exist will fail with :exc:`AttributeError`:: + + >>> @patch('sys.non_existing_attribute', 42) + ... def test(): + ... assert sys.non_existing_attribute == 42 + ... + >>> test() + Traceback (most recent call last): + ... + AttributeError: <module 'sys' (built-in)> does not have the attribute 'non_existing' + +but adding ``create=True`` in the call to :func:`patch` will make the previous example +work as expected:: + + >>> @patch('sys.non_existing_attribute', 42, create=True) + ... def test(mock_stdout): + ... assert sys.non_existing_attribute == 42 + ... + >>> test() + patch.object ~~~~~~~~~~~~ |