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.

Fix pytest-dev#7110

.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_asynctest.py

@@ -0,0 +1,13 @@
+"""Issue #7110"""
+import asyncio
+
+import asynctest
+
+
+class Test(asynctest.TestCase):
+    async def test_error(self):
+        await asyncio.sleep(0)
+        self.fail("failing on purpose")
+
+    async def test_ok(self):
+        await asyncio.sleep(0)

testing/test_unittest.py

@@ -1137,3 +1137,12 @@ def test_async_support(testdir):
     testdir.copy_example("unittest/test_unittest_asyncio.py")
     reprec = testdir.inline_run()
     reprec.assertoutcome(failed=1, passed=1)
+
+
+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=1)

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:}