[feat] The asyncio_event_loop mark provides a module-scoped asyncio event loop when a module has the mark.

Signed-off-by: Michael Seifert <m.seifert@digitalernachschub.de>

Author: seifertm

docs/source/reference/markers.rst

@@ -32,10 +32,10 @@ automatically to *async* test functions.
 
 ``pytest.mark.asyncio_event_loop``
 ==================================
-Test classes with this mark provide a class-scoped asyncio event loop.
+Test classes or modules with this mark provide a class-scoped or module-scoped asyncio event loop.
 
 This functionality is orthogonal to the `asyncio` mark.
-That means the presence of this mark does not imply that async test functions inside the class are collected by pytest-asyncio.
+That means the presence of this mark does not imply that async test functions inside the class or module are collected by pytest-asyncio.
 The collection happens automatically in `auto` mode.
 However, if you're using strict mode, you still have to apply the `asyncio` mark to your async test functions.
 
@@ -79,8 +79,33 @@ In *auto* mode, the ``pytest.mark.asyncio`` marker can be omitted:
         async def test_this_runs_in_same_loop(self):
             assert asyncio.get_running_loop() is TestClassScopedLoop.loop
 
+Similarly, a module-scoped loop is provided when adding the _asyncio_event_loop_ mark to the module:
 
+.. code-block:: python
+
+    import asyncio
+
+    import pytest
+
+    pytestmark = pytest.mark.asyncio_event_loop
+
+    loop: asyncio.AbstractEventLoop
 
 
+    async def test_remember_loop():
+        global loop
+        loop = asyncio.get_running_loop()
+
+
+    async def test_this_runs_in_same_loop():
+        global loop
+        assert asyncio.get_running_loop() is loop
+
+
+    class TestClassA:
+        async def test_this_runs_in_same_loop(self):
+            global loop
+            assert asyncio.get_running_loop() is loop
+
 .. |pytestmark| replace:: ``pytestmark``
 .. _pytestmark: http://doc.pytest.org/en/latest/example/markers.html#marking-whole-classes-or-modules

pytest_asyncio/plugin.py

@@ -180,7 +180,8 @@ def pytest_configure(config: Config) -> None:
     config.addinivalue_line(
         "markers",
         "asyncio_event_loop: "
-        "Provides an asyncio event loop in the scope of the marked test class",
+        "Provides an asyncio event loop in the scope of the marked test "
+        "class or module",
     )
 
 
@@ -347,7 +348,7 @@ def pytest_pycollect_makeitem(
 
 @pytest.hookimpl
 def pytest_collectstart(collector: pytest.Collector):
-    if not isinstance(collector, pytest.Class):
+    if not isinstance(collector, (pytest.Class, pytest.Module)):
         return
     # pytest.Collector.own_markers is empty at this point,
     # so we rely on _pytest.mark.structures.get_unpacked_marks
@@ -357,17 +358,20 @@ def pytest_collectstart(collector: pytest.Collector):
             continue
 
         @pytest.fixture(
-            scope="class",
+            scope="class" if isinstance(collector, pytest.Class) else "module",
             name="event_loop",
         )
-        def scoped_event_loop(cls) -> Iterator[asyncio.AbstractEventLoop]:
+        def scoped_event_loop(
+            *args,  # Function needs to accept "cls" when collected by pytest.Class
+        ) -> Iterator[asyncio.AbstractEventLoop]:
             loop = asyncio.get_event_loop_policy().new_event_loop()
             yield loop
             loop.close()
 
         # @pytest.fixture does not register the fixture anywhere, so pytest doesn't
         # know it exists. We work around this by attaching the fixture function to the
         # collected Python class, where it will be picked up by pytest.Class.collect()
+        # or pytest.Module.collect(), respectively
         collector.obj.__pytest_asyncio_scoped_event_loop = scoped_event_loop
         break
 

tests/markers/test_module_marker.py

@@ -50,3 +50,66 @@ def sample_fixture():
     )
     result = pytester.runpytest("--asyncio-mode=strict")
     result.assert_outcomes(passed=2)
+
+
+def test_asyncio_mark_provides_module_scoped_loop_strict_mode(pytester: Pytester):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import asyncio
+            import pytest
+
+            pytestmark = pytest.mark.asyncio_event_loop
+
+            loop: asyncio.AbstractEventLoop
+
+            @pytest.mark.asyncio
+            async def test_remember_loop():
+                global loop
+                loop = asyncio.get_running_loop()
+
+            @pytest.mark.asyncio
+            async def test_this_runs_in_same_loop():
+                global loop
+                assert asyncio.get_running_loop() is loop
+
+            class TestClassA:
+                @pytest.mark.asyncio
+                async def test_this_runs_in_same_loop(self):
+                    global loop
+                    assert asyncio.get_running_loop() is loop
+            """
+        )
+    )
+    result = pytester.runpytest("--asyncio-mode=strict")
+    result.assert_outcomes(passed=3)
+
+
+def test_asyncio_mark_provides_class_scoped_loop_auto_mode(pytester: Pytester):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import asyncio
+            import pytest
+
+            pytestmark = pytest.mark.asyncio_event_loop
+
+            loop: asyncio.AbstractEventLoop
+
+            async def test_remember_loop():
+                global loop
+                loop = asyncio.get_running_loop()
+
+            async def test_this_runs_in_same_loop():
+                global loop
+                assert asyncio.get_running_loop() is loop
+
+            class TestClassA:
+                async def test_this_runs_in_same_loop(self):
+                    global loop
+                    assert asyncio.get_running_loop() is loop
+            """
+        )
+    )
+    result = pytester.runpytest("--asyncio-mode=auto")
+    result.assert_outcomes(passed=3)