Add real async iterator for ByteStreams

httpx/_content.py

@@ -35,8 +35,25 @@ def __init__(self, stream: bytes) -> None:
     def __iter__(self) -> Iterator[bytes]:
         yield self._stream
 
-    async def __aiter__(self) -> AsyncIterator[bytes]:
-        yield self._stream
+    def __aiter__(self) -> AsyncIterator[bytes]:
+        return _ByteStreamAsyncIterator(self._stream)
+
+
+class _ByteStreamAsyncIterator:
+    __slots__ = ("_stream",)
+
+    def __init__(self, stream: bytes) -> None:
+        self._stream: bytes | None = stream
+
+    def __aiter__(self) -> _ByteStreamAsyncIterator:
+        return self
+
+    async def __anext__(self) -> bytes:
+        stream = self._stream
+        if stream is None:
+            raise StopAsyncIteration
+        self._stream = None  # Consumed.
+        return stream
 
 
 class IteratorByteStream(SyncByteStream):

tests/test_content.py

@@ -32,6 +32,10 @@ async def test_bytes_content():
     sync_content = b"".join(list(request.stream))
     async_content = b"".join([part async for part in request.stream])
 
+    # The async iterator returned by __aiter__ is itself an async iterator.
+    async_iterator = request.stream.__aiter__()
+    assert async_iterator.__aiter__() is async_iterator
+
     assert request.headers == {"Host": "www.example.com", "Content-Length": "13"}
     assert sync_content == b"Hello, world!"
     assert async_content == b"Hello, world!"