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

Fri Sep 20 00:04:22 EDT 2019

https://github.com/python/cpython/commit/8b03f943c37e07fb2394acdcfacd066647f9b1fd
commit: 8b03f943c37e07fb2394acdcfacd066647f9b1fd
branch: master
author: Lisa Roach <lisaroach14 at gmail.com>
committer: GitHub <noreply at github.com>
date: 2019年09月19日T21:04:18-07:00
summary:
bpo-38093: Correctly returns AsyncMock for async subclasses. (GH-15947)
files:
A Misc/NEWS.d/next/Library/2019-09-11-14-45-30.bpo-38093.yQ6k7y.rst
M Doc/library/unittest.mock-examples.rst
M Lib/unittest/mock.py
M Lib/unittest/test/testmock/testasync.py
M Lib/unittest/test/testmock/testmagicmethods.py

diff --git a/Doc/library/unittest.mock-examples.rst b/Doc/library/unittest.mock-examples.rst
index cf6b671b5bee..e650bb1e23e0 100644
--- a/Doc/library/unittest.mock-examples.rst
+++ b/Doc/library/unittest.mock-examples.rst
@@ -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
diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 4cf8e60ccc15..0a16e26f1d8a 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -983,9 +983,13 @@ def _get_child_mock(self, /, **kw):
 _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) :
@@ -1881,7 +1885,7 @@ def _patch_stopall():
 '__reduce__', '__reduce_ex__', '__getinitargs__', '__getnewargs__',
 '__getstate__', '__setstate__', '__getformat__', '__setformat__',
 '__repr__', '__dir__', '__subclasses__', '__format__',
- '__getnewargs_ex__', '__aenter__', '__aexit__', '__anext__', '__aiter__',
+ '__getnewargs_ex__',
 }
 
 
@@ -1900,10 +1904,12 @@ def method(self, /, *args, **kw):
 
 # 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__',
diff --git a/Lib/unittest/test/testmock/testasync.py b/Lib/unittest/test/testmock/testasync.py
index 87f3cfc8fa47..0d68c9757980 100644
--- a/Lib/unittest/test/testmock/testasync.py
+++ b/Lib/unittest/test/testmock/testasync.py
@@ -382,35 +382,88 @@ def test_add_side_effect_iterable(self):
 class AsyncContextManagerTest(unittest.TestCase):
 
 class WithAsyncContextManager:
-
 async def __aenter__(self, *args, **kwargs):
 return self
 
 async def __aexit__(self, *args, **kwargs):
 pass
 
- 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 cm_mock as result:
+ called = True
+ return result
 
- async def use_context_manager():
- nonlocal called
- async with mock_instance as result:
- called = True
- return result
+ 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)
 
- result = asyncio.run(use_context_manager())
- self.assertTrue(called)
- self.assertTrue(mock_instance.__aenter__.called)
- self.assertTrue(mock_instance.__aexit__.called)
- self.assertIsNot(mock_instance, result)
- self.assertIsInstance(result, AsyncMock)
 
 def test_mock_customize_async_context_manager(self):
 instance = self.WithAsyncContextManager()
@@ -478,27 +531,30 @@ def __aiter__(self):
 
 raise StopAsyncIteration
 
- def test_mock_aiter_and_anext(self):
- instance = self.WithAsyncIterator()
- mock_instance = MagicMock(instance)
-
- self.assertEqual(asyncio.iscoroutine(instance.__aiter__),
- asyncio.iscoroutine(mock_instance.__aiter__))
- self.assertEqual(asyncio.iscoroutine(instance.__anext__),
- asyncio.iscoroutine(mock_instance.__anext__))
-
- iterator = instance.__aiter__()
- if asyncio.iscoroutine(iterator):
- iterator = asyncio.run(iterator)
-
- mock_iterator = mock_instance.__aiter__()
- if asyncio.iscoroutine(mock_iterator):
- mock_iterator = asyncio.run(mock_iterator)
+ 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])
+
+ 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__))
+
+ for mock_type in [AsyncMock, MagicMock]:
+ with self.subTest(f"test aiter and anext corourtine with {mock_type}"):
+ inner_test(mock_type)
 
- 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):
@@ -509,19 +565,30 @@ def test_mock_async_for(self):
 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):
diff --git a/Lib/unittest/test/testmock/testmagicmethods.py b/Lib/unittest/test/testmock/testmagicmethods.py
index 130a3397ba0d..57f85e951e20 100644
--- a/Lib/unittest/test/testmock/testmagicmethods.py
+++ b/Lib/unittest/test/testmock/testmagicmethods.py
@@ -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 @@ def test_magic_mock_equality(self):
 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 @@ def test_magicmock_defaults(self):
 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
diff --git a/Misc/NEWS.d/next/Library/2019-09-11-14-45-30.bpo-38093.yQ6k7y.rst b/Misc/NEWS.d/next/Library/2019-09-11-14-45-30.bpo-38093.yQ6k7y.rst
new file mode 100644
index 000000000000..24a53013cec7
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-09-11-14-45-30.bpo-38093.yQ6k7y.rst
@@ -0,0 +1,2 @@
+Fixes AsyncMock so it doesn't crash when used with AsyncContextManagers
+or AsyncIterators.
