support partials in asyncio.iscoroutinefunction

Lib/asyncio/coroutines.py

@@ -19,8 +19,11 @@ def _is_debug_mode():
 
 def iscoroutinefunction(func):
     """Return True if func is a decorated coroutine function."""
-    return (inspect.iscoroutinefunction(func) or
-            getattr(func, '_is_coroutine', None) is _is_coroutine)
+    return (
+        inspect.iscoroutinefunction(func)
+        or getattr(func, '_is_coroutine', None) is _is_coroutine
+        or getattr(functools._unwrap_partial(func), "_is_coroutine", None) is _is_coroutine
+    )
 
 
 # Prioritize native coroutine check to speed-up

Lib/test/test_asyncio/test_tasks.py

@@ -1644,9 +1644,27 @@ def fn1():
             yield
         self.assertFalse(asyncio.iscoroutinefunction(fn1))
 
-        async def fn2():
+        def fn2():
             pass
+
+        fn2._is_coroutine = asyncio.coroutines._is_coroutine
+
         self.assertTrue(asyncio.iscoroutinefunction(fn2))
+        self.assertTrue(asyncio.iscoroutinefunction(functools.partial(fn2)))
+        self.assertTrue(asyncio.iscoroutinefunction(functools.partial(functools.partial(fn2))))
+
+        async def async_fn():
+            pass
+
+        self.assertTrue(asyncio.iscoroutinefunction(afn2))
+
+        def sync_fn():
+            pass
+
+        partial_sync_fn = functools.partial(sync_fn)
+        partial_sync_fn._is_coroutine = asyncio.coroutines._is_coroutine
+
+        self.assertTrue(asyncio.iscoroutinefunction(partial_sync_fn))
 
         self.assertFalse(asyncio.iscoroutinefunction(mock.Mock()))
         self.assertTrue(asyncio.iscoroutinefunction(mock.AsyncMock()))