[3.14] GH-135171: Revert async generator expressions behavior (#135352)

Lib/test/test_asyncgen.py

@@ -1835,6 +1835,20 @@ async def run():
         res = self.loop.run_until_complete(run())
         self.assertEqual(res, [i * 2 for i in range(1, 10)])
 
+    def test_async_gen_expression_incorrect(self):
+        async def ag():
+            yield 42
+
+        async def run(arg):
+            (x async for x in arg)
+
+        err_msg_async = "'async for' requires an object with " \
+            "__aiter__ method, got .*"
+
+        self.loop.run_until_complete(run(ag()))
+        with self.assertRaisesRegex(TypeError, err_msg_async):
+            self.loop.run_until_complete(run(None))
+
     def test_asyncgen_nonstarted_hooks_are_cancellable(self):
         # See https://bugs.python.org/issue38013
         messages = []

Lib/test/test_coroutines.py

@@ -2267,7 +2267,7 @@ def c():
 
     def test_call_aiter_once_in_comprehension(self):
 
-        class Iterator:
+        class AsyncIterator:
 
             def __init__(self):
                 self.val = 0
@@ -2283,12 +2283,17 @@ async def __anext__(self):
         class C:
 
             def __aiter__(self):
-                return Iterator()
+                return AsyncIterator()
 
-        async def run():
+        async def run_listcomp():
             return [i async for i in C()]
 
-        self.assertEqual(run_async(run()), ([], [1,2]))
+        async def run_asyncgen():
+            ag = (i async for i in C())
+            return [i async for i in ag]
+
+        self.assertEqual(run_async(run_listcomp()), ([], [1, 2]))
+        self.assertEqual(run_async(run_asyncgen()), ([], [1, 2]))
 
 
 @unittest.skipIf(

Lib/test/test_generators.py

@@ -288,7 +288,7 @@ class C:
             def __iter__(self):
                 return Iterator()
 
-        self.assertEqual([1,2], list(i for i in C()))
+        self.assertEqual([1, 2], list(i for i in C()))
 
 
 class ModifyUnderlyingIterableTest(unittest.TestCase):

Lib/test/test_listcomps.py

@@ -770,7 +770,7 @@ class C:
             def __iter__(self):
                 return Iterator()
 
-        self.assertEqual([1,2], [i for i in C()])
+        self.assertEqual([1, 2], [i for i in C()])
 
 __test__ = {'doctests' : doctests}