Only set chat_history if there is None

This allows for the chat_history not to be blown away by a default instance.

src/generation/chat/mod.rs

@@ -207,15 +207,14 @@ impl Ollama {
     /// Without impact for existing history
     /// Used to prepare history for request
     fn get_chat_messages_by_id(&mut self, history_id: impl ToString) -> Vec<ChatMessage> {
-        let mut binding = {
-            let new_history =
-                std::sync::Arc::new(std::sync::RwLock::new(MessagesHistory::default()));
-            self.messages_history = Some(new_history);
-            self.messages_history.clone().unwrap()
-        };
         let chat_history = match self.messages_history.as_mut() {
             Some(history) => history,
-            None => &mut binding,
+            None => {
+                let new_history =
+                    std::sync::Arc::new(std::sync::RwLock::new(MessagesHistory::default()));
+                self.messages_history = Some(new_history);
+                &mut self.messages_history.clone().unwrap()
+            }
         };
         // Clone the current chat messages to avoid borrowing issues
         // And not to add message to the history if the request fails

tests/chat_history_management.rs

@@ -1,4 +1,7 @@
-use ollama_rs::Ollama;
+use ollama_rs::{
+    generation::chat::{request::ChatMessageRequest, ChatMessage, MessageRole},
+    Ollama,
+};
 
 #[test]
 fn test_chat_history_saved_as_should() {
@@ -111,3 +114,39 @@ fn test_chat_history_freed_if_limit_exceeded() {
     assert!(last.is_some());
     assert_eq!(last.unwrap().content, "Hi again".to_string());
 }
+
+#[tokio::test]
+async fn test_chat_history_accumulated() {
+    let mut ollama = Ollama::new_default_with_history(30);
+    let chat_id = "default";
+
+    assert!(ollama
+        .send_chat_messages_with_history(
+            ChatMessageRequest::new(
+                "granite-code:3b".into(),
+                vec![ChatMessage::new(
+                    MessageRole::User,
+                    "Why is the sky blue?".into(),
+                )],
+            ),
+            chat_id,
+        )
+        .await
+        .is_ok());
+
+    assert!(ollama
+        .send_chat_messages_with_history(
+            ChatMessageRequest::new(
+                "granite-code:3b".into(),
+                vec![ChatMessage::new(
+                    MessageRole::User,
+                    "But, why is the sky blue?".into()
+                )]
+            ),
+            chat_id
+        )
+        .await
+        .is_ok());
+
+    assert_eq!(ollama.get_messages_history(chat_id).unwrap().len(), 4)
+}