Fix test helper to avoid unwrap

codex-rs/core/src/chat_completions.rs

@@ -462,3 +462,98 @@ pub(crate) trait AggregateStreamExt: Stream<Item = Result<ResponseEvent>> + Size
 }
 
 impl<T> AggregateStreamExt for T where T: Stream<Item = Result<ResponseEvent>> + Sized {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use futures::StreamExt;
+    use tokio_util::io::ReaderStream;
+
+    /// Helper that feeds the provided SSE content into `process_chat_sse` and
+    /// collects all resulting `ResponseEvent`s.
+    async fn collect_events(sse: &str, aggregate: bool) -> Vec<ResponseEvent> {
+        let (tx, rx) = tokio::sync::mpsc::channel::<Result<ResponseEvent>>(16);
+
+        // ReaderStream turns the in-memory string into an async byte stream.
+        let stream = ReaderStream::new(std::io::Cursor::new(sse.to_string())).map_err(CodexErr::Io);
+
+        tokio::spawn(process_chat_sse(stream, tx));
+
+        let response_stream = ResponseStream { rx_event: rx };
+        let mut stream: Pin<Box<dyn Stream<Item = Result<ResponseEvent>>>> = if aggregate {
+            Box::pin(response_stream.aggregate())
+        } else {
+            Box::pin(response_stream)
+        };
+
+        let mut events = Vec::new();
+        while let Some(ev) = stream.next().await {
+            match ev {
+                Ok(ev) => events.push(ev),
+                Err(err) => panic!("stream error: {err}"),
+            }
+        }
+        events
+    }
+
+    /// Split assistant message chunks are concatenated into a single message and
+    /// followed by a Completed event.
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn aggregates_text_deltas() {
+        let sse = concat!(
+            "data: {\"id\":\"1\",\"choices\":[{\"delta\":{\"content\":\"Hello\"},\"index\":0,\"finish_reason\":null}]}\n\n",
+            "data: {\"id\":\"1\",\"choices\":[{\"delta\":{\"content\":\" world\"},\"index\":0,\"finish_reason\":null}]}\n\n",
+            "data: {\"id\":\"1\",\"choices\":[{\"delta\":{},\"index\":0,\"finish_reason\":\"stop\"}],\"usage\":{}}\n\n"
+        );
+
+        let events = collect_events(sse, true).await;
+
+        assert_eq!(events.len(), 2, "expected aggregated message and Completed");
+
+        match &events[0] {
+            ResponseEvent::OutputItemDone(ResponseItem::Message { role, content }) => {
+                assert_eq!(role, "assistant");
+                assert_eq!(content.len(), 1);
+                if let crate::models::ContentItem::OutputText { text } = &content[0] {
+                    assert_eq!(text, "Hello world");
+                } else {
+                    panic!("unexpected content variant");
+                }
+            }
+            other => panic!("unexpected first event: {other:?}"),
+        }
+
+        assert!(matches!(events[1], ResponseEvent::Completed { .. }));
+    }
+
+    /// Function call arguments arriving in multiple chunks are merged into a
+    /// single `FunctionCall` item and the stream ends with `Completed`.
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn merges_function_call_arguments() {
+        let sse = concat!(
+            "data: {\"id\":\"chatcmpl-123\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"id\":\"call_123\",\"type\":\"function\",\"function\":{\"name\":\"get_weather\"}}]},\"finish_reason\":null,\"index\":0}]}\n\n",
+            "data: {\"id\":\"chatcmpl-123\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"function\":{\"arguments\":\"{\\\"location\\\":\\\"San Franci\"}}]},\"finish_reason\":null,\"index\":0}]}\n\n",
+            "data: {\"id\":\"chatcmpl-123\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"function\":{\"arguments\":\"sco\\\"}\"}}]},\"finish_reason\":null,\"index\":0}]}\n\n",
+            "data: {\"id\":\"chatcmpl-123\",\"model\":\"gpt-4o\",\"choices\":[{\"delta\":{},\"finish_reason\":\"tool_calls\",\"index\":0}],\"usage\":{}}\n\n"
+        );
+
+        let events = collect_events(sse, false).await;
+
+        assert_eq!(events.len(), 2, "function call and Completed expected");
+
+        match &events[0] {
+            ResponseEvent::OutputItemDone(ResponseItem::FunctionCall {
+                name,
+                arguments,
+                call_id,
+            }) => {
+                assert_eq!(name, "get_weather");
+                assert_eq!(call_id, "call_123");
+                assert_eq!(arguments, "{\"location\":\"San Francisco\"}");
+            }
+            other => panic!("unexpected first event: {other:?}"),
+        }
+
+        assert!(matches!(events[1], ResponseEvent::Completed { .. }));
+    }
+}