• bpo-44185: unittest.mock.mock_open() will call the close() method of the file handle mock when it is exiting from the context manager. Patch by Samet Yaslan.

  • gh-94924: unittest.mock.create_autospec() now properly returns coroutine functions compatible with inspect.iscoroutinefunction()

  • bpo-17013: Add ThreadingMock to unittest.mock that can be used to create Mock objects that can wait until they are called. Patch by Karthikeyan Singaravelan and Mario Corchero.

  • bpo-41768: unittest.mock speccing no longer calls class properties. Patch by Melanie Witt.


  • gh-102978: Fixes unittest.mock.patch() not enforcing function signatures for methods decorated with @classmethod or @staticmethod when patch is called with autospec=True.

  • gh-103329: Regression tests for the behaviour of unittest.mock.PropertyMock were added.


  • gh-100740: Fix unittest.mock.Mock not respecting the spec for attribute names prefixed with assert.

  • gh-100690: Mock objects which are not unsafe will now raise an AttributeError when accessing an attribute that matches the name of an assertion but without the prefix assert_, e.g. accessing called_once instead of assert_called_once. This is in addition to this already happening for accessing attributes with prefixes assert, assret, asert, aseert, and assrt.

  • gh-96127: inspect.signature was raising TypeError on call with mock objects. Now it correctly returns (*args, **kwargs) as infered signature.


  • gh-98624: Add a mutex to unittest.mock.NonCallableMock to protect concurrent access to mock attributes.

  • bpo-43478: Mocks can no longer be used as the specs for other Mocks. As a result, an already-mocked object cannot have an attribute mocked using autospec=True or be the subject of a create_autospec(…) call. This can uncover bugs in tests since these Mock-derived Mocks will always pass certain tests (e.g. isinstance) and builtin assert functions (e.g. assert_called_once_with) will unconditionally pass.

  • bpo-45156: Fixes infinite loop on unittest.mock.seal() of mocks created by create_autospec().

  • bpo-41403: Make mock.patch() raise a TypeError with a relevant error message on invalid arg. Previously it allowed a cryptic AttributeError to escape.

  • gh-91803: Fix an error when using a method of objects mocked with unittest.mock.create_autospec() after it was sealed with unittest.mock.seal() function.

  • bpo-41877: AttributeError for suspected misspellings of assertions on mocks are now pointing out that the cause are misspelled assertions and also what to do if the misspelling is actually an intended attribute name. The unittest.mock document is also updated to reflect the current set of recognised misspellings.

  • bpo-43478: Mocks can no longer be provided as the specs for other Mocks. As a result, an already-mocked object cannot be passed to mock.Mock(). This can uncover bugs in tests since these Mock-derived Mocks will always pass certain tests (e.g. isinstance) and builtin assert functions (e.g. assert_called_once_with) will unconditionally pass.

  • bpo-45010: Remove support of special method __div__ in unittest.mock. It is not used in Python 3.

  • gh-84753: inspect.iscoroutinefunction() now properly returns True when an instance of unittest.mock.AsyncMock is passed to it. This makes it consistent with behavior of asyncio.iscoroutinefunction(). Patch by Mehdi ABAAKOUK.

  • bpo-46852: Remove the undocumented private float.__set_format__() method, previously known as float.__setformat__() in Python 3.7. Its docstring said: “You probably don’t want to use this function. It exists mainly to be used in Python’s test suite.” Patch by Victor Stinner.

  • gh-98086: Make sure patch.dict() can be applied on async functions.

  • gh-100287: Fix the interaction of unittest.mock.seal() with unittest.mock.AsyncMock.

  • gh-83076: Instantiation of Mock() and AsyncMock() is now 3.8x faster.

  • bpo-41877: A check is added against misspellings of autospect, auto_spec and set_spec being passed as arguments to patch, patch.object and create_autospec.


  • bpo-42532: Remove unexpected call of __bool__ when passing a spec_arg argument to a Mock.

  • bpo-39966: Revert bpo-25597. unittest.mock.MagicMock with wraps’ set uses default return values for magic methods.

  • bpo-41877: Mock objects which are not unsafe will now raise an AttributeError if an attribute with the prefix asert, aseert, or assrt is accessed, in addition to this already happening for the prefixes assert or assret.

  • bpo-40126: Fixed reverting multiple patches in unittest.mock. Patcher’s __exit__() is now never called if its __enter__() is failed. Returning true from __exit__() silences now the exception.



  • Remove the universal marker from the wheel.


  • No Changes from 4.0.0b1.


  • The release is a fresh cut of cpython’s 4a686504. All changes to mock from that commit and before are included in this release along with the subsequent changes listed below.

  • bpo-37972: Subscripts to the objects now receive the same chaining mechanism as any other custom attributes, so that the following usage no longer raises a TypeError:


    Patch by blhsing

  • bpo-38839: Fix some unused functions in tests. Patch by Adam Johnson.

  • bpo-39485: Fix a bug in unittest.mock.create_autospec() that would complain about the wrong number of arguments for custom descriptors defined in an extension module returning functions.

  • bpo-39082: Allow AsyncMock to correctly patch static/class methods

  • bpo-38093: Fixes AsyncMock so it doesn’t crash when used with AsyncContextManagers or AsyncIterators.

  • bpo-38859: AsyncMock now returns StopAsyncIteration on the exaustion of a side_effects iterable. Since PEP-479 its Impossible to raise a StopIteration exception from a coroutine.

  • bpo-38163: Child mocks will now detect their type as either synchronous or asynchronous, asynchronous child mocks will be AsyncMocks and synchronous child mocks will be either MagicMock or Mock (depending on their parent type).

  • bpo-38473: Use signature from inner mock for autospecced methods attached with unittest.mock.attach_mock(). Patch by Karthikeyan Singaravelan.

  • bpo-38136: Changes AsyncMock call count and await count to be two different counters. Now await count only counts when a coroutine has been awaited, not when it has been called, and vice-versa. Update the documentation around this.

  • bpo-37555: Fix NonCallableMock._call_matcher returning tuple instead of _Call object when self._spec_signature exists. Patch by Elizabeth Uselton

  • bpo-37251: Remove __code__ check in AsyncMock that incorrectly evaluated function specs as async objects but failed to evaluate classes with __await__ but no __code__ attribute defined as async objects.

  • bpo-38669: Raise TypeError when passing target as a string with unittest.mock.patch.object().

  • bpo-25597: Ensure, if wraps is supplied to unittest.mock.MagicMock, it is used to calculate return values for the magic methods instead of using the default return values. Patch by Karthikeyan Singaravelan.

  • bpo-38108: Any synchronous magic methods on an AsyncMock now return a MagicMock. Any asynchronous magic methods on a MagicMock now return an AsyncMock.

  • bpo-21478: Record calls to parent when autospecced object is attached to a mock using unittest.mock.attach_mock(). Patch by Karthikeyan Singaravelan.

  • bpo-38857: AsyncMock fix for return values that are awaitable types. This also covers side_effect iterable values that happend to be awaitable, and wraps callables that return an awaitable type. Before these awaitables were being awaited instead of being returned as is.

  • bpo-38932: Mock fully resets child objects on reset_mock(). Patch by Vegard Stikbakke

  • bpo-37685: Fixed __eq__, __lt__ etc implementations in some classes. They now return NotImplemented for unsupported type of the other operand. This allows the other operand to play role (for example the equality comparison with ANY will return True).

  • bpo-37212: now preserves the order of keyword arguments in repr output. Patch by Karthikeyan Singaravelan.

  • bpo-37828: Fix default mock name in unittest.mock.Mock.assert_called() exceptions. Patch by Abraham Toriz Cruz.

  • bpo-36871: Improve error handling for the assert_has_calls and assert_has_awaits methods of mocks. Fixed a bug where any errors encountered while binding the expected calls to the mock’s spec were silently swallowed, leading to misleading error output.

  • bpo-21600: Fix mock.patch.stopall() to stop active patches that were created with mock.patch.dict().

  • bpo-38161: Removes _AwaitEvent from AsyncMock.

  • bpo-36871: Ensure method signature is used instead of constructor signature of a class while asserting mock object against method calls. Patch by Karthikeyan Singaravelan.


  • bpo-31855: unittest.mock.mock_open() results now respects the argument of read([size]). Patch contributed by Rémi Lapeyre.


  • Include the license, readme and changelog in the source distribution.


  • Fixed patching of dictionaries, when specifying the target with a unicode on Python 2.


  • Add missing funcsigs dependency on Python 2.


  • Fix packaging issue where six was missed as a dependency.


  • bpo-35226: Recursively check arguments when testing for equality of objects and add note that tracking of parameters used to create ancestors of mocks in mock_calls is not possible.

  • bpo-31177: Fix bug that prevented using reset_mock on mock instances with deleted attributes

  • bpo-26704: Added test demonstrating double-patching of an instance method. Patch by Anthony Sottile.

  • bpo-35500: Write expected and actual call parameters on separate lines in unittest.mock.Mock.assert_called_with() assertion errors. Contributed by Susan Su.

  • bpo-35330: When a Mock instance was used to wrap an object, if side_effect is used in one of the mocks of it methods, don’t call the original implementation and return the result of using the side effect the same way that it is done with return_value.

  • bpo-30541: Add new function to seal a mock and prevent the automatically creation of child mocks. Patch by Mario Corchero.

  • bpo-35022: unittest.mock.MagicMock now supports the __fspath__ method (from os.PathLike).

  • bpo-33516: unittest.mock.MagicMock now supports the __round__ magic method.

  • bpo-35512: unittest.mock.patch.dict() used as a decorator with string target resolves the target during function call instead of during decorator construction. Patch by Karthikeyan Singaravelan.

  • bpo-36366: Calling stop() on an unstarted or stopped unittest.mock.patch() object will now return None instead of raising RuntimeError, making the method idempotent. Patch byKarthikeyan Singaravelan.

  • bpo-35357: Internal attributes’ names of unittest.mock._Call and unittest.mock.MagicProxy (name, parent & from_kall) are now prefixed with _mock_ in order to prevent clashes with widely used object attributes. Fixed minor typo in test function name.

  • bpo-20239: Allow repeated assignment deletion of unittest.mock.Mock attributes. Patch by Pablo Galindo.

  • bpo-35082: Don’t return deleted attributes when calling dir on a unittest.mock.Mock.

  • bpo-0: Improved an error message when mock assert_has_calls fails.

  • bpo-23078: Add support for classmethod() and staticmethod() to unittest.mock.create_autospec(). Initial patch by Felipe Ochoa.

  • bpo-21478: Calls to a child function created with unittest.mock.create_autospec() should propagate to the parent. Patch by Karthikeyan Singaravelan.

  • bpo-36598: Fix isinstance check for Mock objects with spec when the code is executed under tracing. Patch by Karthikeyan Singaravelan.

  • bpo-32933: unittest.mock.mock_open() now supports iteration over the file contents. Patch by Tony Flury.

  • bpo-21269: Add args and kwargs properties to mock call objects. Contributed by Kumar Akshay.

  • bpo-17185: Set __signature__ on mock for inspect to get signature. Patch by Karthikeyan Singaravelan.

  • bpo-35047: unittest.mock now includes mock calls in exception messages if assert_not_called, assert_called_once, or assert_called_once_with fails. Patch by Petter Strandmark.

  • bpo-28380: unittest.mock Mock autospec functions now properly support assert_called, assert_not_called, and assert_called_once.

  • bpo-28735: Fixed the comparison of mock.MagickMock with mock.ANY.

  • bpo-20804: The unittest.mock.sentinel attributes now preserve their identity when they are copied or pickled.

  • bpo-28961: Fix unittest.mock._Call helper: don’t ignore the name parameter anymore. Patch written by Jiajun Huang.

  • bpo-26750: unittest.mock.create_autospec() now works properly for subclasses of property() and other data descriptors.

  • bpo-21271: New keyword only parameters in reset_mock call.

  • bpo-26807: mock_open ‘files’ no longer error on readline at end of file. Patch from Yolanda Robla.

  • bpo-25195: Fix a regression in mock.MagicMock. _Call is a subclass of tuple (changeset 3603bae63c13 only works for classes) so we need to implement __ne__ ourselves. Patch by Andrew Plummer.

2.0.0 and earlier

  • bpo-26323: Add Mock.assert_called() and Mock.assert_called_once() methods to unittest.mock. Patch written by Amit Saha.

  • bpo-22138: Fix mock.patch behavior when patching descriptors. Restore original values after patching. Patch contributed by Sean McCully.

  • bpo-24857: Comparing call_args to a long sequence now correctly returns a boolean result instead of raising an exception. Patch by A Kaptur.

  • bpo-23004: mock_open() now reads binary data correctly when the type of read_data is bytes. Initial patch by Aaron Hill.

  • bpo-21750: mock_open.read_data can now be read from each instance, as it could in Python 3.3.

  • bpo-18622: unittest.mock.mock_open().reset_mock would recurse infinitely. Patch from Nicola Palumbo and Laurent De Buyst.

  • bpo-23661: unittest.mock side_effects can now be exceptions again. This was a regression vs Python 3.4. Patch from Ignacio Rossi

  • bpo-23310: Fix MagicMock’s initializer to work with __methods__, just like configure_mock(). Patch by Kasia Jachim.

  • bpo-23568: Add rdivmod support to MagicMock() objects. Patch by Håkan Lövdahl.

  • bpo-23581: Add matmul support to MagicMock. Patch by Håkan Lövdahl.

  • bpo-23326: Removed __ne__ implementations. Since fixing default __ne__ implementation in bpo-21408 they are redundant. * NOT BACKPORTED *

  • bpo-21270: We now override tuple methods in objects so that they can be used as normal call attributes.

  • bpo-21256: Printout of keyword args should be in deterministic order in a mock function call. This will help to write better doctests.

  • bpo-21262: New method assert_not_called for Mock. It raises AssertionError if the mock has been called.

  • bpo-21238: New keyword argument unsafe to Mock. It raises AttributeError incase of an attribute startswith assert or assret.

  • bpo-21239: patch.stopall() didn’t work deterministically when the same name was patched more than once.

  • bpo-21222: Passing name keyword argument to mock.create_autospec now works.

  • bpo-17826: setting an iterable side_effect on a mock function created by create_autospec now works. Patch by Kushal Das.

  • bpo-17826: setting an iterable side_effect on a mock function created by create_autospec now works. Patch by Kushal Das.

  • bpo-20968: unittest.mock.MagicMock now supports division. Patch by Johannes Baiter.

  • bpo-20189: unittest.mock now no longer assumes that any object for which it could get an inspect.Signature is a callable written in Python. Fix courtesy of Michael Foord.

  • bpo-17467: add readline and readlines support to mock_open in unittest.mock.

  • bpo-17015: When it has a spec, a Mock object now inspects its signature when matching calls, so that arguments can be matched positionally or by name.

  • bpo-15323: improve failure message of Mock.assert_called_once_with

  • bpo-14857: fix regression in references to PEP 3135 implicit __class__ closure variable (Reopens bpo-12370)

  • bpo-14295: Add unittest.mock