change implementation so the check happens in pytest_fixture_setup after any hooks (from async plugins) has had a chance to resolve the awaitable

Author: jakkdl

src/_pytest/compat.py

@@ -44,6 +44,7 @@ class NotSetType(enum.Enum):
 
 
 def is_generator(func: object) -> bool:
+    # note: this also returns true for async generator functions
     genfunc = inspect.isgeneratorfunction(func)
     return genfunc and not iscoroutinefunction(func)
 

src/_pytest/fixtures.py

@@ -595,42 +595,6 @@ def _get_active_fixturedef(
             raise FixtureLookupError(argname, self)
         fixturedef = fixturedefs[index]
 
-        # Check for attempted use of an async fixture by a sync test
-        # `self.scope` here is not the scope of the requested fixture, but the scope of
-        # the requester.
-        if (
-            self.scope == "function"
-            and not inspect.iscoroutinefunction(self._pyfuncitem.obj)
-            and (
-                inspect.iscoroutinefunction(fixturedef.func)
-                or inspect.isasyncgenfunction(fixturedef.func)
-            )
-        ):
-            if fixturedef._autouse:
-                warnings.warn(
-                    PytestRemovedIn9Warning(
-                        f"Sync test {self._pyfuncitem.name!r} requested async fixture "
-                        f"{argname!r} with autouse=True. "
-                        "If you intended to use the fixture you may want to make the "
-                        "test asynchronous or the fixture synchronous. "
-                        "If you did not intend to use it you should "
-                        "restructure your test setup. "
-                        "This will turn into an error in pytest 9."
-                    ),
-                    stacklevel=3,
-                )
-            else:
-                warnings.warn(
-                    PytestRemovedIn9Warning(
-                        f"Sync test {self._pyfuncitem.name!r} requested async fixture "
-                        f"{argname!r}. "
-                        "You may want to make the test asynchronous and run it with "
-                        "a suitable async framework test plugin, or make the fixture synchronous. "
-                        "This will turn into an error in pytest 9."
-                    ),
-                    stacklevel=3,
-                )
-
         # Prepare a SubRequest object for calling the fixture.
         try:
             callspec = self._pyfuncitem.callspec
@@ -921,6 +885,8 @@ def call_fixture_func(
     fixturefunc: _FixtureFunc[FixtureValue], request: FixtureRequest, kwargs
 ) -> FixtureValue:
     if is_generator(fixturefunc):
+        # note: this also triggers on async generators, suppressing 'unawaited coroutine'
+        # warning.
         fixturefunc = cast(
             Callable[..., Generator[FixtureValue, None, None]], fixturefunc
         )
@@ -1179,6 +1145,25 @@ def pytest_fixture_setup(
 
     fixturefunc = resolve_fixture_function(fixturedef, request)
     my_cache_key = fixturedef.cache_key(request)
+
+    if inspect.isasyncgenfunction(fixturefunc) or inspect.iscoroutinefunction(
+        fixturefunc
+    ):
+        auto_str = " with autouse=True" if fixturedef._autouse else ""
+
+        warnings.warn(
+            PytestRemovedIn9Warning(
+                f"{request.node.name!r} requested an async fixture "
+                f"{request.fixturename!r}{auto_str}, with no plugin or hook that "
+                "handled it. This is usually an error, as pytest does not natively "
+                "support it. If this is intentional, consider making the fixture "
+                "sync and return a coroutine/asyncgen. "
+                "This will turn into an error in pytest 9."
+            ),
+            # no stacklevel will point at users code, so we just point here
+            stacklevel=1,
+        )
+
     try:
         result = call_fixture_func(fixturefunc, request, kwargs)
     except TEST_OUTCOME as e:

testing/acceptance_test.py

@@ -1306,11 +1306,13 @@ def test_foo(async_fixture):
     result = pytester.runpytest()
     result.stdout.fnmatch_lines(
         [
+            "*== warnings summary ==*",
             (
-                "*Sync test 'test_foo' requested async fixture "
-                "'async_fixture'. "
-                "You may want to make the test asynchronous and run it with "
-                "a suitable async framework test plugin, or make the fixture synchronous. "
+                "*PytestRemovedIn9Warning: 'test_foo' requested an async "
+                "fixture 'async_fixture', with no plugin or hook that handled it. "
+                "This is usually an error, as pytest does not natively support it. "
+                "If this is intentional, consider making the fixture sync and return "
+                "a coroutine/asyncgen. "
                 "This will turn into an error in pytest 9."
             ),
         ]
@@ -1328,21 +1330,21 @@ async def async_fixture():
                 yield
 
             def test_foo(async_fixture):
-                # suppress unawaited coroutine warning
-                try:
-                    async_fixture.asend(None)
-                except StopIteration:
-                    pass
+                # we don't need to suppress RuntimeWarning for unawaited coroutine
+                # as pytest internals accidentally do so already for async gens
+                ...
         """
     )
     result = pytester.runpytest()
     result.stdout.fnmatch_lines(
         [
+            "*== warnings summary ==*",
             (
-                "*Sync test 'test_foo' requested async fixture "
-                "'async_fixture'. "
-                "You may want to make the test asynchronous and run it with "
-                "a suitable async framework test plugin, or make the fixture synchronous. "
+                "*PytestRemovedIn9Warning: 'test_foo' requested an async "
+                "fixture 'async_fixture', with no plugin or hook that handled it. "
+                "This is usually an error, as pytest does not natively support it. "
+                "If this is intentional, consider making the fixture sync and return "
+                "a coroutine/asyncgen. "
                 "This will turn into an error in pytest 9."
             ),
         ]
@@ -1371,13 +1373,13 @@ def test_foo(async_fixture):
     result = pytester.runpytest()
     result.stdout.fnmatch_lines(
         [
+            "*== warnings summary ==*",
             (
-                "*Sync test 'test_foo' requested async fixture "
-                "'async_fixture' with autouse=True. "
-                "If you intended to use the fixture you may want to make the "
-                "test asynchronous or the fixture synchronous. "
-                "If you did not intend to use it you should "
-                "restructure your test setup. "
+                "*PytestRemovedIn9Warning: Sync test 'test_foo' requested an async "
+                "fixture 'async_fixture' with autouse=True, with no plugin or hook "
+                "that handled it. This is usually an error, as pytest does not "
+                "natively support it. If this is intentional, consider making the "
+                "fixture sync and return a coroutine/asyncgen. "
                 "This will turn into an error in pytest 9."
             ),
         ]