Fix receiver aiter and anext interface. (#215)

src/heisskleber/core/receiver.py

@@ -1,7 +1,6 @@
 """Asynchronous data source interface."""
 
 from abc import ABC, abstractmethod
-from collections.abc import AsyncGenerator
 from types import TracebackType
 from typing import Any, Generic
 
@@ -56,20 +55,32 @@ class Receiver(ABC, Generic[T_co]):
     def __repr__(self) -> str:
         """A string reprensatiion of the source."""
 
-    async def __aiter__(self) -> AsyncGenerator[tuple[T_co, dict[str, Any]], None]:
-        """Implement async iteration over the source's data stream.
+    def __aiter__(self) -> "Receiver[T_co]":
+        """Return self as the async iterator object.
 
-        Yields:
-            tuple[T_co, dict[str, Any]]: Each data item and its associated metadata
-                as returned by receive().
+        This method enables the receiver to be used in async for loops.
+
+        Returns:
+            Self as the async iterator.
+        """
+        return self
+
+    async def __anext__(self) -> tuple[T_co, dict[str, Any]]:
+        """Get the next item from the receiver's data stream.
+
+        This method implements async iteration by calling the receive() method
+        and returning its result.
+
+        Returns:
+            tuple[T_co, dict[str, Any]]: The next data item and its associated
+                metadata as returned by receive().
 
         Raises:
-            Any exceptions that might occur during receive().
-
+            StopAsyncIteration: When the receiver has no more data.
+            Any other exceptions that might occur during receive().
         """
-        while True:
-            data, meta = await self.receive()
-            yield data, meta
+        data, meta = await self.receive()
+        return data, meta
 
     async def __aenter__(self) -> "Receiver[T_co]":
         """Initialize the source for use in an async context manager.

tests/core/test_receiver.py

@@ -0,0 +1,50 @@
+from typing import Any
+
+import pytest
+
+from heisskleber import Receiver
+
+
+class MockReceiver(Receiver):
+    def __init__(self) -> None:
+        self.n_called = 0
+
+    async def receive(self) -> tuple[bool, dict[str, Any]]:
+        self.n_called += 1
+        return True, {"msg": "Called MockReceiver", "count": self.n_called}
+
+    async def start(self) -> None:
+        return
+
+    async def stop(self) -> None:
+        return
+
+    def __repr__(self) -> str:
+        return "MockReceiver"
+
+
+@pytest.mark.asyncio
+async def test_mock_receiver_can_be_iterated_over() -> None:
+    count = 1
+
+    async for data, meta in MockReceiver():
+        assert data
+        assert "msg" in meta
+        assert meta["count"] == count
+        count += 1
+        if count == 3:
+            break
+
+
+@pytest.mark.asyncio
+async def test_mock_receiver_call_anext() -> None:
+    receiver = MockReceiver()
+
+    data, meta = await anext(receiver)
+
+    assert data
+    assert meta["count"] == 1
+
+    data, meta = await anext(receiver)
+
+    assert meta["count"] == 2