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[3.8] bpo-38093: Correctly returns AsyncMock for async subclasses. (GH-15947) (GH-16299) 

(cherry picked from commit 8b03f943c3)

Co-authored-by: Lisa Roach <lisaroach14@gmail.com>
This commit is contained in:
Lisa Roach 2019-09-20 23:00:04 -07:00 committed by Stéphane Wirtel
parent f4e0ceb211
commit 865bb685a6
5 changed files with 177 additions and 74 deletions
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31
Doc/library/unittest.mock-examples.rst
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@ -14,7 +14,7 @@
import asyncio
import unittest
from unittest.mock import Mock, MagicMock, patch, call, sentinel
from unittest.mock import Mock, MagicMock, AsyncMock, patch, call, sentinel
class SomeClass:
attribute = 'this is a doctest'
@ -280,14 +280,16 @@ function returns is what the call returns:
Mocking asynchronous iterators
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Since Python 3.8, ``MagicMock`` has support to mock :ref:`async-iterators`
through ``__aiter__``. The :attr:`~Mock.return_value` attribute of ``__aiter__``
can be used to set the return values to be used for iteration.
Since Python 3.8, ``AsyncMock`` and ``MagicMock`` have support to mock
:ref:`async-iterators` through ``__aiter__``. The :attr:`~Mock.return_value`
attribute of ``__aiter__`` can be used to set the return values to be used for
iteration.
>>> mock = MagicMock()
>>> mock = MagicMock() # AsyncMock also works here
>>> mock.__aiter__.return_value = [1, 2, 3]
>>> async def main():
... return [i async for i in mock]
...
>>> asyncio.run(main())
[1, 2, 3]
@ -295,24 +297,25 @@ can be used to set the return values to be used for iteration.
Mocking asynchronous context manager
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Since Python 3.8, ``MagicMock`` has support to mock
:ref:`async-context-managers` through ``__aenter__`` and ``__aexit__``. The
return value of ``__aenter__`` is an :class:`AsyncMock`.
Since Python 3.8, ``AsyncMock`` and ``MagicMock`` have support to mock
:ref:`async-context-managers` through ``__aenter__`` and ``__aexit__``.
By default, ``__aenter__`` and ``__aexit__`` are ``AsyncMock`` instances that
return an async function.
>>> class AsyncContextManager:
...
... async def __aenter__(self):
... return self
...
... async def __aexit__(self):
... async def __aexit__(self, exc_type, exc, tb):
... pass
>>> mock_instance = MagicMock(AsyncContextManager())
...
>>> mock_instance = MagicMock(AsyncContextManager()) # AsyncMock also works here
>>> async def main():
... async with mock_instance as result:
... pass
...
>>> asyncio.run(main())
>>> mock_instance.__aenter__.assert_called_once()
>>> mock_instance.__aexit__.assert_called_once()
>>> mock_instance.__aenter__.assert_awaited_once()
>>> mock_instance.__aexit__.assert_awaited_once()
Creating a Mock from an Existing Object

18
Lib/unittest/mock.py
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@ -988,9 +988,13 @@ class NonCallableMock(Base):
_type = type(self)
if issubclass(_type, MagicMock) and _new_name in _async_method_magics:
klass = AsyncMock
if issubclass(_type, AsyncMockMixin):
elif _new_name in _sync_async_magics:
# Special case these ones b/c users will assume they are async,
# but they are actually sync (ie. __aiter__)
klass = MagicMock
if not issubclass(_type, CallableMixin):
elif issubclass(_type, AsyncMockMixin):
klass = AsyncMock
elif not issubclass(_type, CallableMixin):
if issubclass(_type, NonCallableMagicMock):
klass = MagicMock
elif issubclass(_type, NonCallableMock) :
@ -1867,7 +1871,7 @@ _non_defaults = {
'__reduce__', '__reduce_ex__', '__getinitargs__', '__getnewargs__',
'__getstate__', '__setstate__', '__getformat__', '__setformat__',
'__repr__', '__dir__', '__subclasses__', '__format__',
'__getnewargs_ex__', '__aenter__', '__aexit__', '__anext__', '__aiter__',
'__getnewargs_ex__',
}
@ -1886,10 +1890,12 @@ _magics = {
# Magic methods used for async `with` statements
_async_method_magics = {"__aenter__", "__aexit__", "__anext__"}
# `__aiter__` is a plain function but used with async calls
_async_magics = _async_method_magics | {"__aiter__"}
# Magic methods that are only used with async calls but are synchronous functions themselves
_sync_async_magics = {"__aiter__"}
_async_magics = _async_method_magics | _sync_async_magics
_all_magics = _magics | _non_defaults
_all_sync_magics = _magics | _non_defaults
_all_magics = _all_sync_magics | _async_magics
_unsupported_magics = {
'__getattr__', '__setattr__',

165
Lib/unittest/test/testmock/testasync.py
View File

@ -377,10 +377,6 @@ class AsyncArguments(unittest.TestCase):
class AsyncContextManagerTest(unittest.TestCase):
class WithAsyncContextManager:
def __init__(self):
self.entered = False
self.exited = False
async def __aenter__(self, *args, **kwargs):
self.entered = True
return self
@ -388,32 +384,81 @@ class AsyncContextManagerTest(unittest.TestCase):
async def __aexit__(self, *args, **kwargs):
self.exited = True
def test_magic_methods_are_async_mocks(self):
mock = MagicMock(self.WithAsyncContextManager())
self.assertIsInstance(mock.__aenter__, AsyncMock)
self.assertIsInstance(mock.__aexit__, AsyncMock)
class WithSyncContextManager:
def __enter__(self, *args, **kwargs):
return self
def __exit__(self, *args, **kwargs):
pass
class ProductionCode:
# Example real-world(ish) code
def __init__(self):
self.session = None
async def main(self):
async with self.session.post('https://python.org') as response:
val = await response.json()
return val
def test_async_magic_methods_are_async_mocks_with_magicmock(self):
cm_mock = MagicMock(self.WithAsyncContextManager())
self.assertIsInstance(cm_mock.__aenter__, AsyncMock)
self.assertIsInstance(cm_mock.__aexit__, AsyncMock)
def test_magicmock_has_async_magic_methods(self):
cm = MagicMock(name='magic_cm')
self.assertTrue(hasattr(cm, "__aenter__"))
self.assertTrue(hasattr(cm, "__aexit__"))
def test_magic_methods_are_async_functions(self):
cm = MagicMock(name='magic_cm')
self.assertIsInstance(cm.__aenter__, AsyncMock)
self.assertIsInstance(cm.__aexit__, AsyncMock)
# AsyncMocks are also coroutine functions
self.assertTrue(asyncio.iscoroutinefunction(cm.__aenter__))
self.assertTrue(asyncio.iscoroutinefunction(cm.__aexit__))
def test_set_return_value_of_aenter(self):
def inner_test(mock_type):
pc = self.ProductionCode()
pc.session = MagicMock(name='sessionmock')
cm = mock_type(name='magic_cm')
response = AsyncMock(name='response')
response.json = AsyncMock(return_value={'json': 123})
cm.__aenter__.return_value = response
pc.session.post.return_value = cm
result = asyncio.run(pc.main())
self.assertEqual(result, {'json': 123})
for mock_type in [AsyncMock, MagicMock]:
with self.subTest(f"test set return value of aenter with {mock_type}"):
inner_test(mock_type)
def test_mock_supports_async_context_manager(self):
called = False
instance = self.WithAsyncContextManager()
mock_instance = MagicMock(instance)
def inner_test(mock_type):
called = False
cm = self.WithAsyncContextManager()
cm_mock = mock_type(cm)
async def use_context_manager():
nonlocal called
async with mock_instance as result:
called = True
return result
async def use_context_manager():
nonlocal called
async with cm_mock as result:
called = True
return result
result = asyncio.run(use_context_manager())
self.assertFalse(instance.entered)
self.assertFalse(instance.exited)
self.assertTrue(called)
self.assertTrue(mock_instance.entered)
self.assertTrue(mock_instance.exited)
self.assertTrue(mock_instance.__aenter__.called)
self.assertTrue(mock_instance.__aexit__.called)
self.assertIsNot(mock_instance, result)
self.assertIsInstance(result, AsyncMock)
cm_result = asyncio.run(use_context_manager())
self.assertTrue(called)
self.assertTrue(cm_mock.__aenter__.called)
self.assertTrue(cm_mock.__aexit__.called)
cm_mock.__aenter__.assert_awaited()
cm_mock.__aexit__.assert_awaited()
# We mock __aenter__ so it does not return self
self.assertIsNot(cm_mock, cm_result)
for mock_type in [AsyncMock, MagicMock]:
with self.subTest(f"test context manager magics with {mock_type}"):
inner_test(mock_type)
def test_mock_customize_async_context_manager(self):
instance = self.WithAsyncContextManager()
@ -481,27 +526,30 @@ class AsyncIteratorTest(unittest.TestCase):
raise StopAsyncIteration
def test_mock_aiter_and_anext(self):
instance = self.WithAsyncIterator()
mock_instance = MagicMock(instance)
def test_aiter_set_return_value(self):
mock_iter = AsyncMock(name="tester")
mock_iter.__aiter__.return_value = [1, 2, 3]
async def main():
return [i async for i in mock_iter]
result = asyncio.run(main())
self.assertEqual(result, [1, 2, 3])
self.assertEqual(asyncio.iscoroutine(instance.__aiter__),
asyncio.iscoroutine(mock_instance.__aiter__))
self.assertEqual(asyncio.iscoroutine(instance.__anext__),
asyncio.iscoroutine(mock_instance.__anext__))
def test_mock_aiter_and_anext_asyncmock(self):
def inner_test(mock_type):
instance = self.WithAsyncIterator()
mock_instance = mock_type(instance)
# Check that the mock and the real thing bahave the same
# __aiter__ is not actually async, so not a coroutinefunction
self.assertFalse(asyncio.iscoroutinefunction(instance.__aiter__))
self.assertFalse(asyncio.iscoroutinefunction(mock_instance.__aiter__))
# __anext__ is async
self.assertTrue(asyncio.iscoroutinefunction(instance.__anext__))
self.assertTrue(asyncio.iscoroutinefunction(mock_instance.__anext__))
iterator = instance.__aiter__()
if asyncio.iscoroutine(iterator):
iterator = asyncio.run(iterator)
for mock_type in [AsyncMock, MagicMock]:
with self.subTest(f"test aiter and anext corourtine with {mock_type}"):
inner_test(mock_type)
mock_iterator = mock_instance.__aiter__()
if asyncio.iscoroutine(mock_iterator):
mock_iterator = asyncio.run(mock_iterator)
self.assertEqual(asyncio.iscoroutine(iterator.__aiter__),
asyncio.iscoroutine(mock_iterator.__aiter__))
self.assertEqual(asyncio.iscoroutine(iterator.__anext__),
asyncio.iscoroutine(mock_iterator.__anext__))
def test_mock_async_for(self):
async def iterate(iterator):
@ -512,19 +560,30 @@ class AsyncIteratorTest(unittest.TestCase):
return accumulator
expected = ["FOO", "BAR", "BAZ"]
with self.subTest("iterate through default value"):
mock_instance = MagicMock(self.WithAsyncIterator())
self.assertEqual([], asyncio.run(iterate(mock_instance)))
def test_default(mock_type):
mock_instance = mock_type(self.WithAsyncIterator())
self.assertEqual(asyncio.run(iterate(mock_instance)), [])
with self.subTest("iterate through set return_value"):
mock_instance = MagicMock(self.WithAsyncIterator())
def test_set_return_value(mock_type):
mock_instance = mock_type(self.WithAsyncIterator())
mock_instance.__aiter__.return_value = expected[:]
self.assertEqual(expected, asyncio.run(iterate(mock_instance)))
self.assertEqual(asyncio.run(iterate(mock_instance)), expected)
with self.subTest("iterate through set return_value iterator"):
mock_instance = MagicMock(self.WithAsyncIterator())
def test_set_return_value_iter(mock_type):
mock_instance = mock_type(self.WithAsyncIterator())
mock_instance.__aiter__.return_value = iter(expected[:])
self.assertEqual(expected, asyncio.run(iterate(mock_instance)))
self.assertEqual(asyncio.run(iterate(mock_instance)), expected)
for mock_type in [AsyncMock, MagicMock]:
with self.subTest(f"default value with {mock_type}"):
test_default(mock_type)
with self.subTest(f"set return_value with {mock_type}"):
test_set_return_value(mock_type)
with self.subTest(f"set return_value iterator with {mock_type}"):
test_set_return_value_iter(mock_type)
class AsyncMockAssert(unittest.TestCase):

35
Lib/unittest/test/testmock/testmagicmethods.py
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@ -1,8 +1,9 @@
import asyncio
import math
import unittest
import os
import sys
from unittest.mock import Mock, MagicMock, _magics
from unittest.mock import AsyncMock, Mock, MagicMock, _magics
@ -271,6 +272,34 @@ class TestMockingMagicMethods(unittest.TestCase):
self.assertEqual(mock != mock, False)
# This should be fixed with issue38163
@unittest.expectedFailure
def test_asyncmock_defaults(self):
mock = AsyncMock()
self.assertEqual(int(mock), 1)
self.assertEqual(complex(mock), 1j)
self.assertEqual(float(mock), 1.0)
self.assertNotIn(object(), mock)
self.assertEqual(len(mock), 0)
self.assertEqual(list(mock), [])
self.assertEqual(hash(mock), object.__hash__(mock))
self.assertEqual(str(mock), object.__str__(mock))
self.assertTrue(bool(mock))
self.assertEqual(round(mock), mock.__round__())
self.assertEqual(math.trunc(mock), mock.__trunc__())
self.assertEqual(math.floor(mock), mock.__floor__())
self.assertEqual(math.ceil(mock), mock.__ceil__())
self.assertTrue(asyncio.iscoroutinefunction(mock.__aexit__))
self.assertTrue(asyncio.iscoroutinefunction(mock.__aenter__))
self.assertIsInstance(mock.__aenter__, AsyncMock)
self.assertIsInstance(mock.__aexit__, AsyncMock)
# in Python 3 oct and hex use __index__
# so these tests are for __index__ in py3k
self.assertEqual(oct(mock), '0o1')
self.assertEqual(hex(mock), '0x1')
# how to test __sizeof__ ?
def test_magicmock_defaults(self):
mock = MagicMock()
self.assertEqual(int(mock), 1)
@ -286,6 +315,10 @@ class TestMockingMagicMethods(unittest.TestCase):
self.assertEqual(math.trunc(mock), mock.__trunc__())
self.assertEqual(math.floor(mock), mock.__floor__())
self.assertEqual(math.ceil(mock), mock.__ceil__())
self.assertTrue(asyncio.iscoroutinefunction(mock.__aexit__))
self.assertTrue(asyncio.iscoroutinefunction(mock.__aenter__))
self.assertIsInstance(mock.__aenter__, AsyncMock)
self.assertIsInstance(mock.__aexit__, AsyncMock)
# in Python 3 oct and hex use __index__
# so these tests are for __index__ in py3k

2
Misc/NEWS.d/next/Library/2019-09-11-14-45-30.bpo-38093.yQ6k7y.rst Normal file
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@ -0,0 +1,2 @@
Fixes AsyncMock so it doesn't crash when used with AsyncContextManagers
or AsyncIterators.