[refactor] Run parametrized loop test inside Pytester to prevent the …

…event loop implementation from polluting the test environment.

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

tests/async_fixtures/test_parametrized_loop.py

@@ -1,31 +1,46 @@
-import asyncio
+from textwrap import dedent
 
-import pytest
+from pytest import Pytester
 
-TESTS_COUNT = 0
 
+def test_event_loop_parametrization(pytester: Pytester):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import asyncio
 
-def teardown_module():
-    # parametrized 2 * 2 times: 2 for 'event_loop' and 2 for 'fix'
-    assert TESTS_COUNT == 4
+            import pytest
+            import pytest_asyncio
 
+            TESTS_COUNT = 0
 
-@pytest.fixture(scope="module", params=[1, 2])
-def event_loop(request):
-    request.param
-    loop = asyncio.new_event_loop()
-    yield loop
-    loop.close()
 
+            def teardown_module():
+                # parametrized 2 * 2 times: 2 for 'event_loop' and 2 for 'fix'
+                assert TESTS_COUNT == 4
 
-@pytest.fixture(params=["a", "b"])
-async def fix(request):
-    await asyncio.sleep(0)
-    return request.param
 
+            @pytest.fixture(scope="module", params=[1, 2])
+            def event_loop(request):
+                request.param
+                loop = asyncio.new_event_loop()
+                yield loop
+                loop.close()
 
-@pytest.mark.asyncio
-async def test_parametrized_loop(fix):
-    await asyncio.sleep(0)
-    global TESTS_COUNT
-    TESTS_COUNT += 1
+
+            @pytest_asyncio.fixture(params=["a", "b"])
+            async def fix(request):
+                await asyncio.sleep(0)
+                return request.param
+
+
+            @pytest.mark.asyncio
+            async def test_parametrized_loop(fix):
+                await asyncio.sleep(0)
+                global TESTS_COUNT
+                TESTS_COUNT += 1
+            """
+        )
+    )
+    result = pytester.runpytest_subprocess("--asyncio-mode=strict")
+    result.assert_outcomes(passed=4)