Let unittest frameworks deal with async functions

Instead of trying to handle unittest-async functions in pytest_pyfunc_call,
let the unittest framework handle them instead.

This lets us remove the hack in pytest_pyfunc_call, with the upside that
we should support any unittest-async based framework.

Also included 'asynctest' as test dependency for py37-twisted, and renamed
'twisted' to 'unittestextras' to better reflect that we install 'twisted' and
'asynctest' now.

This also fixes the problem of cleanUp functions not being properly called
for async functions.

Fix #7110
Fix #6924

Author: nicoddemus

.github/workflows/main.yml

@@ -70,7 +70,7 @@ jobs:
           - name: "windows-py38"
             python: "3.8"
             os: windows-latest
-            tox_env: "py38-twisted"
+            tox_env: "py38-unittestextras"
             use_coverage: true
 
           - name: "ubuntu-py35"

src/_pytest/compat.py

@@ -93,6 +93,13 @@ def syntax, and doesn't contain yield), or a function decorated with
     return inspect.iscoroutinefunction(func) or getattr(func, "_is_coroutine", False)
 
 
+def is_async_function(func: object) -> bool:
+    """Return True if the given function seems to be an async function or async generator"""
+    return iscoroutinefunction(func) or (
+        sys.version_info >= (3, 6) and inspect.isasyncgenfunction(func)
+    )
+
+
 def getlocation(function, curdir=None) -> str:
     function = get_real_func(function)
     fn = py.path.local(inspect.getfile(function))

src/_pytest/python.py

@@ -34,8 +34,8 @@
 from _pytest.compat import get_real_func
 from _pytest.compat import getimfunc
 from _pytest.compat import getlocation
+from _pytest.compat import is_async_function
 from _pytest.compat import is_generator
-from _pytest.compat import iscoroutinefunction
 from _pytest.compat import NOTSET
 from _pytest.compat import REGEX_TYPE
 from _pytest.compat import safe_getattr
@@ -159,7 +159,7 @@ def pytest_configure(config):
     )
 
 
-def async_warn(nodeid: str) -> None:
+def async_warn_and_skip(nodeid: str) -> None:
     msg = "async def functions are not natively supported and have been skipped.\n"
     msg += (
         "You need to install a suitable plugin for your async framework, for example:\n"
@@ -175,33 +175,13 @@ def async_warn(nodeid: str) -> None:
 @hookimpl(trylast=True)
 def pytest_pyfunc_call(pyfuncitem: "Function"):
     testfunction = pyfuncitem.obj
-
-    try:
-        # ignoring type as the import is  invalid in py37  and mypy thinks its a error
-        from unittest import IsolatedAsyncioTestCase  # type: ignore
-    except ImportError:
-        async_ok_in_stdlib = False
-    else:
-        async_ok_in_stdlib = isinstance(
-            getattr(testfunction, "__self__", None), IsolatedAsyncioTestCase
-        )
-
-    if (
-        iscoroutinefunction(testfunction)
-        or (sys.version_info >= (3, 6) and inspect.isasyncgenfunction(testfunction))
-    ) and not async_ok_in_stdlib:
-        async_warn(pyfuncitem.nodeid)
+    if is_async_function(testfunction):
+        async_warn_and_skip(pyfuncitem.nodeid)
     funcargs = pyfuncitem.funcargs
     testargs = {arg: funcargs[arg] for arg in pyfuncitem._fixtureinfo.argnames}
     result = testfunction(**testargs)
     if hasattr(result, "__await__") or hasattr(result, "__aiter__"):
-        if async_ok_in_stdlib:
-            # todo: investigate moving this to the unittest plugin
-            #       by a test call result hook
-            testcase = testfunction.__self__
-            testcase._callMaybeAsync(lambda: result)
-        else:
-            async_warn(pyfuncitem.nodeid)
+        async_warn_and_skip(pyfuncitem.nodeid)
     return True
 
 

src/_pytest/unittest.py

@@ -6,6 +6,7 @@
 import _pytest._code
 import pytest
 from _pytest.compat import getimfunc
+from _pytest.compat import is_async_function
 from _pytest.config import hookimpl
 from _pytest.outcomes import exit
 from _pytest.outcomes import fail
@@ -227,13 +228,17 @@ def wrapped_testMethod(*args, **kwargs):
                 self._needs_explicit_tearDown = True
                 raise _GetOutOf_testPartExecutor(exc)
 
-        setattr(self._testcase, self._testcase._testMethodName, wrapped_testMethod)
-        try:
-            self._testcase(result=self)
-        except _GetOutOf_testPartExecutor as exc:
-            raise exc.args[0] from exc.args[0]
-        finally:
-            delattr(self._testcase, self._testcase._testMethodName)
+        # let the unittest framework handle async functions
+        if is_async_function(self.obj):
+            self._testcase(self)
+        else:
+            setattr(self._testcase, self._testcase._testMethodName, wrapped_testMethod)
+            try:
+                self._testcase(result=self)
+            except _GetOutOf_testPartExecutor as exc:
+                raise exc.args[0] from exc.args[0]
+            finally:
+                delattr(self._testcase, self._testcase._testMethodName)
 
     def _prunetraceback(self, excinfo):
         Function._prunetraceback(self, excinfo)

testing/example_scripts/unittest/test_unittest_asyncio.py

@@ -1,7 +1,13 @@
 from unittest import IsolatedAsyncioTestCase  # type: ignore
 
 
+teardowns = []
+
+
 class AsyncArguments(IsolatedAsyncioTestCase):
+    async def asyncTearDown(self):
+        teardowns.append(None)
+
     async def test_something_async(self):
         async def addition(x, y):
             return x + y
@@ -13,3 +19,6 @@ async def addition(x, y):
             return x + y
 
         self.assertEqual(await addition(2, 2), 3)
+
+    def test_teardowns(self):
+        assert len(teardowns) == 2

testing/example_scripts/unittest/test_unittest_asynctest.py

@@ -0,0 +1,22 @@
+"""Issue #7110"""
+import asyncio
+
+import asynctest
+
+
+teardowns = []
+
+
+class Test(asynctest.TestCase):
+    async def tearDown(self):
+        teardowns.append(None)
+
+    async def test_error(self):
+        await asyncio.sleep(0)
+        self.fail("failing on purpose")
+
+    async def test_ok(self):
+        await asyncio.sleep(0)
+
+    def test_teardowns(self):
+        assert len(teardowns) == 2

testing/test_unittest.py

@@ -1136,4 +1136,13 @@ def test_async_support(testdir):
 
     testdir.copy_example("unittest/test_unittest_asyncio.py")
     reprec = testdir.inline_run()
-    reprec.assertoutcome(failed=1, passed=1)
+    reprec.assertoutcome(failed=1, passed=2)
+
+
+def test_asynctest_support(testdir):
+    """Check asynctest support (#7110)"""
+    pytest.importorskip("asynctest")
+
+    testdir.copy_example("unittest/test_unittest_asynctest.py")
+    reprec = testdir.inline_run()
+    reprec.assertoutcome(failed=1, passed=2)

tox.ini

@@ -10,7 +10,7 @@ envlist =
     py37
     py38
     pypy3
-    py37-{pexpect,xdist,twisted,numpy,pluggymaster}
+    py37-{pexpect,xdist,unittestextras,numpy,pluggymaster}
     doctesting
     py37-freeze
     docs
@@ -49,7 +49,8 @@ deps =
     pexpect: pexpect
     pluggymaster: git+https://github.com/pytest-dev/pluggy.git@master
     pygments
-    twisted: twisted
+    unittestextras: twisted
+    unittestextras: asynctest
     xdist: pytest-xdist>=1.13
     {env:_PYTEST_TOX_EXTRA_DEP:}