Change asyncio detection to use get_running_loop

sniffio/_impl.py

@@ -75,15 +75,24 @@ async def generic_sleep(seconds):
     if "asyncio" in sys.modules:
         import asyncio
         try:
-            current_task = asyncio.current_task  # type: ignore[attr-defined]
+            asyncio.get_running_loop()
+            return "asyncio"
+
         except AttributeError:
-            current_task = asyncio.Task.current_task  # type: ignore[attr-defined]
-        try:
-            if current_task() is not None:
-                return "asyncio"
+            try:
+                current_task = asyncio.current_task  # type: ignore[attr-defined]
+            except AttributeError:
+                current_task = asyncio.Task.current_task  # type: ignore[attr-defined]
+            try:
+                if current_task() is not None:
+                    return "asyncio"
+            except RuntimeError:
+                pass
+
         except RuntimeError:
             pass
 
+
     # Sniff for curio (for now)
     if 'curio' in sys.modules:
         from curio.meta import curio_running

sniffio/_tests/test_sniffio.py

@@ -58,6 +58,30 @@ async def this_is_asyncio():
         current_async_library()
 
 
+def test_in_call_soon_threadsafe():
+    import asyncio
+
+    asynclib = None
+
+    def sync_in_loop(completed):
+        nonlocal asynclib
+        try:
+            asynclib = current_async_library()
+        finally:
+            completed.set()
+
+    async def async_in_loop():
+        completed = asyncio.Event()
+        loop.call_soon_threadsafe(sync_in_loop, completed)
+        await completed.wait()
+
+    loop = asyncio.new_event_loop()
+    loop.run_until_complete(async_in_loop())
+    loop.close()
+
+    assert asynclib == 'asyncio'
+
+
 # https://github.com/dabeaz/curio/pull/354
 @pytest.mark.skipif(
     os.name == "nt" and sys.version_info >= (3, 9),