gh-83076: 3.8x speed improvement in (Async)Mock instantiation

Lib/test/test_unittest/testmock/testasync.py

@@ -300,6 +300,19 @@ def test_spec_normal_methods_on_class_with_mock(self):
  self.assertIsInstance(mock.async_method, AsyncMock)
  self.assertIsInstance(mock.normal_method, Mock)
 
+ def test_spec_async_attributes_instance(self):
+ async_instance = AsyncClass()
+ async_instance.async_func_attr = async_func
+ async_instance.later_async_func_attr = normal_func
+
+ mock_async_instance = Mock(spec_set=async_instance)
+
+ async_instance.later_async_func_attr = async_func
+
+ self.assertIsInstance(mock_async_instance.async_func_attr, AsyncMock)
+ # only the shape of the spec at the time of mock construction matters
+ self.assertNotIsInstance(mock_async_instance.later_async_func_attr, AsyncMock)
+
  def test_spec_mock_type_kw(self):
  def inner_test(mock_type):
  async_mock = mock_type(spec=async_func)

Lib/unittest/mock.py

@@ -411,15 +411,18 @@ class NonCallableMock(Base):
  # necessary.
  _lock = RLock()
 
- def __new__(cls, /, *args, **kw):
+ def __new__(
+ cls, spec=None, wraps=None, name=None, spec_set=None,
+ parent=None, _spec_state=None, _new_name='', _new_parent=None,
+ _spec_as_instance=False, _eat_self=None, unsafe=False, **kwargs
+ ):
  # every instance has its own class
  # so we can create magic methods on the
  # class without stomping on other mocks
  bases = (cls,)
  if not issubclass(cls, AsyncMockMixin):
  # Check if spec is an async object or function
- bound_args = _MOCK_SIG.bind_partial(cls, *args, **kw).arguments
- spec_arg = bound_args.get('spec_set', bound_args.get('spec'))
+ spec_arg = spec_set or spec
  if spec_arg is not None and _is_async_obj(spec_arg):
  bases = (AsyncMockMixin, cls)
  new = type(cls.__name__, bases,{'__doc__': cls.__doc__})
@@ -505,10 +508,6 @@ def _mock_add_spec(self, spec, spec_set, _spec_as_instance=False,
  _spec_signature = None
  _spec_asyncs = []
 
- for attr in dir(spec):
- if iscoroutinefunction(getattr(spec, attr, None)):
- _spec_asyncs.append(attr)
-
  if spec is not None and not _is_list(spec):
  if isinstance(spec, type):
  _spec_class = spec
@@ -518,7 +517,13 @@ def _mock_add_spec(self, spec, spec_set, _spec_as_instance=False,
  _spec_as_instance, _eat_self)
  _spec_signature = res and res[1]
 
- spec = dir(spec)
+ spec_list = dir(spec)
+
+ for attr in spec_list:
+ if iscoroutinefunction(getattr(spec, attr, None)):
+ _spec_asyncs.append(attr)
+
+ spec = spec_list
 
  __dict__ = self.__dict__
  __dict__['_spec_class'] = _spec_class
@@ -1057,9 +1062,6 @@ def _calls_repr(self, prefix="Calls"):
  return f"\n{prefix}:{safe_repr(self.mock_calls)}."
 
 
-_MOCK_SIG = inspect.signature(NonCallableMock.__init__)
-
-
 class _AnyComparer(list):
  """A list which checks if it contains a call which may have an
  argument of ANY, flipping the components of item and self from
@@ -2138,10 +2140,8 @@ def mock_add_spec(self, spec, spec_set=False):
 
 
 class AsyncMagicMixin(MagicMixin):
- def __init__(self, /, *args, **kw):
- self._mock_set_magics() # make magic work for kwargs in init
- _safe_super(AsyncMagicMixin, self).__init__(*args, **kw)
- self._mock_set_magics() # fix magic broken by upper level init
+ pass
+
 
 class MagicMock(MagicMixin, Mock):
  """
@@ -2183,6 +2183,10 @@ def __get__(self, obj, _type=None):
  return self.create_mock()
 
 
+_CODE_ATTRS = dir(CodeType)
+_CODE_SIG = inspect.signature(partial(CodeType.__init__, None))
+
+
 class AsyncMockMixin(Base):
  await_count = _delegating_property('await_count')
  await_args = _delegating_property('await_args')
@@ -2200,7 +2204,9 @@ def __init__(self, /, *args, **kwargs):
  self.__dict__['_mock_await_count'] = 0
  self.__dict__['_mock_await_args'] = None
  self.__dict__['_mock_await_args_list'] = _CallList()
- code_mock = NonCallableMock(spec_set=CodeType)
+ code_mock = NonCallableMock(spec_set=_CODE_ATTRS)
+ code_mock.__dict__["_spec_class"] = CodeType
+ code_mock.__dict__["_spec_signature"] = _CODE_SIG
  code_mock.co_flags = inspect.CO_COROUTINE
  self.__dict__['__code__'] = code_mock
  self.__dict__['__name__'] = 'AsyncMock'

Misc/NEWS.d/next/Library/2022-12-14-17-37-01.gh-issue-83076.NaYzWT.rst

@@ -0,0 +1 @@
+Instantiation of ``Mock()`` and ``AsyncMock()`` is now 3.8x faster.