subscribe: drop mapping of AsyncIterable errors

Replicates graphql/graphql-js@541a058

Author: Cito

src/graphql/subscription/map_async_iterator.py

@@ -18,15 +18,9 @@ class MapAsyncIterator:
     be closed.
     """
 
-    def __init__(
-        self,
-        iterable: AsyncIterable,
-        callback: Callable,
-        reject_callback: Optional[Callable] = None,
-    ) -> None:
+    def __init__(self, iterable: AsyncIterable, callback: Callable) -> None:
         self.iterator = iterable.__aiter__()
         self.callback = callback
-        self.reject_callback = reject_callback
         self._close_event = Event()
 
     def __aiter__(self) -> "MapAsyncIterator":
@@ -64,14 +58,10 @@ async def __anext__(self) -> Any:
 
             error = anext.exception()
             if error:
-                if not self.reject_callback or isinstance(
-                    error, (StopAsyncIteration, GeneratorExit)
-                ):
-                    raise error
-                result = self.reject_callback(error)
-            else:
-                value = anext.result()
-                result = self.callback(value)
+                raise error
+
+            value = anext.result()
+            result = self.callback(value)
 
         return await result if isawaitable(result) else result
 

tests/subscription/test_map_async_iterator.py

@@ -284,23 +284,6 @@ async def source():
 
         assert str(exc_info.value) == "Goodbye"
 
-    @mark.asyncio
-    async def maps_over_thrown_errors_if_second_callback_provided():
-        async def source():
-            yield "Hello"
-            raise RuntimeError("Goodbye")
-
-        doubles = MapAsyncIterator(source(), lambda x: x + x, lambda error: error)
-
-        assert await anext(doubles) == "HelloHello"
-
-        result = await anext(doubles)
-        assert isinstance(result, RuntimeError)
-        assert str(result) == "Goodbye"
-
-        with raises(StopAsyncIteration):
-            await anext(doubles)
-
     @mark.asyncio
     async def can_use_simple_iterator_instead_of_generator():
         async def source():