feat: Allow use of "loop_scope" kwarg in asyncio markers.

Author: seifertm

pytest_asyncio/plugin.py

@@ -991,9 +991,21 @@ def pytest_runtest_setup(item: pytest.Item) -> None:
         )
 
 
+_DUPLICATE_LOOP_SCOPE_DEFINITION_ERROR = """\
+An asyncio pytest marker defines both "scope" and "loop_scope", \
+but it should only use "loop_scope".
+"""
+
+
 def _get_marked_loop_scope(asyncio_marker: Mark) -> _ScopeName:
     assert asyncio_marker.name == "asyncio"
-    return asyncio_marker.kwargs.get("scope", "function")
+    if "scope" in asyncio_marker.kwargs and "loop_scope" in asyncio_marker.kwargs:
+        raise pytest.UsageError(_DUPLICATE_LOOP_SCOPE_DEFINITION_ERROR)
+    scope = asyncio_marker.kwargs.get("loop_scope") or asyncio_marker.kwargs.get(
+        "scope", "function"
+    )
+    assert scope in {"function", "class", "module", "package", "session"}
+    return scope
 
 
 def _retrieve_scope_root(item: Union[Collector, Item], scope: str) -> Collector:

tests/markers/test_function_scope.py

@@ -28,6 +28,47 @@ async def test_does_not_run_in_same_loop():
     result.assert_outcomes(passed=2)
 
 
+def test_loop_scope_function_provides_function_scoped_event_loop(pytester: Pytester):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import asyncio
+            import pytest
+
+            pytestmark = pytest.mark.asyncio(loop_scope="function")
+
+            loop: asyncio.AbstractEventLoop
+
+            async def test_remember_loop():
+                global loop
+                loop = asyncio.get_running_loop()
+
+            async def test_does_not_run_in_same_loop():
+                global loop
+                assert asyncio.get_running_loop() is not loop
+            """
+        )
+    )
+    result = pytester.runpytest("--asyncio-mode=strict")
+    result.assert_outcomes(passed=2)
+
+
+def test_raises_when_scope_and_loop_scope_arguments_are_present(pytester: Pytester):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import pytest
+
+            @pytest.mark.asyncio(scope="function", loop_scope="function")
+            async def test_raises():
+                ...
+            """
+        )
+    )
+    result = pytester.runpytest("--asyncio-mode=strict")
+    result.assert_outcomes(errors=1)
+
+
 def test_function_scope_supports_explicit_event_loop_fixture_request(
     pytester: Pytester,
 ):