pythongh-125038: some tests on CHECK_ITERABLE are added

Lib/test/test_asyncgen.py

@@ -1798,12 +1798,6 @@ 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):
-        err_msg = "'async for' requires an object with " \
-            "__aiter__ method, got int"
-        with self.assertRaisesRegex(TypeError, err_msg):
-            g = (x async for x in 42)
-
     def test_asyncgen_nonstarted_hooks_are_cancellable(self):
         # See https://bugs.python.org/issue38013
         messages = []

Lib/test/test_generators.py

@@ -341,6 +341,104 @@ def get_generator_genfunc(obj):
         self.process_tests(get_generator_genfunc)
 
 
+class SequenceClass:
+    def __init__(self, n):
+        self.n = n
+    def __getitem__(self, i):
+        if 0 <= i < self.n:
+            return i
+        else:
+            raise IndexError
+
+
+class IncorrectIterable:
+    def __iter__(self):
+        return 123
+
+
+class IncorrectAsyncIterable:
+    def __aiter__(self):
+        return 123
+
+
+class CheckIterableTest(unittest.TestCase):
+    sequences = (
+        (1, 2),
+        [1, 2, 3],
+        range(42),
+        SequenceClass(10),
+    )
+
+    non_iterables = (
+        None,
+        42,
+        13.0,
+    )
+
+    err_msg_sync = "'.*' object is not iterable"
+    err_msg_async = "'async for' requires an object with " \
+        "__aiter__ method, got .*"
+
+    def test_sequences(self):
+        for seq in self.sequences:
+            (x for x in seq)
+            (x for x in iter(seq))
+            with self.assertRaisesRegex(TypeError, self.err_msg_async):
+                (x async for x in seq)
+            with self.assertRaisesRegex(TypeError, self.err_msg_async):
+                (x async for x in iter(seq))
+
+    def test_non_iterables(self):
+        for obj in self.non_iterables:
+            with self.assertRaisesRegex(TypeError, self.err_msg_sync):
+                (x for x in obj)
+            with self.assertRaisesRegex(TypeError, self.err_msg_async):
+                (x async for x in obj)
+
+    def test_generators(self):
+        def gen():
+            yield 1
+
+        (x for x in gen())
+        (x for x in iter(gen()))
+
+        with self.assertRaisesRegex(TypeError, self.err_msg_async):
+            (x async for x in gen())
+        with self.assertRaisesRegex(TypeError, self.err_msg_async):
+            (x async for x in iter(gen()))
+
+    def test_async_generators(self):
+        async def agen():
+            yield 1
+            yield 2
+
+        with self.assertRaisesRegex(TypeError, self.err_msg_sync):
+            (x for x in agen())
+        with self.assertRaisesRegex(TypeError, self.err_msg_sync):
+            (x for x in aiter(agen()))
+
+        (x async for x in agen())
+        (x async for x in aiter(agen()))
+
+    def test_incorrect_iterable(self):
+        g = (x for x in IncorrectIterable())
+        err_msg = ".* returned non-iterator of type '.*'"
+        with self.assertRaisesRegex(TypeError, err_msg):
+            list(g)
+
+    def test_incorrect_async_iterable(self):
+        g = (x async for x in IncorrectAsyncIterable())
+
+        async def coroutine():
+            async for x in g:
+                pass
+
+        err_msg = "'async for' received an object from __aiter__ " \
+            "that does not implement __anext__: .*"
+        with self.assertRaisesRegex(TypeError, err_msg):
+            coroutine().send(None)
+
+
 class ExceptionTest(unittest.TestCase):
     # Tests for the issue #23353: check that the currently handled exception
     # is correctly saved/restored in PyEval_EvalFrameEx().