Add separate util for hallucination and add tests for it (#203)

crates/prompt_gateway/src/hallucination.rs

@@ -0,0 +1,39 @@
+use common::{common_types::open_ai::Message, consts::USER_ROLE};
+
+pub fn extract_messages_for_hallucination(messages: &Vec<Message>) -> Vec<String> {
+    let all_user_messages = messages
+        .iter()
+        .filter(|m| m.role == USER_ROLE)
+        .map(|m| m.content.as_ref().unwrap().clone())
+        .collect::<Vec<String>>();
+    return all_user_messages;
+}
+
+#[cfg(test)]
+mod test {
+    use common::common_types::open_ai::Message;
+
+    use super::extract_messages_for_hallucination;
+
+    #[test]
+    fn test_hallucination_message() {
+      let test_str = r#"
+      [
+        {
+          "role": "system",
+          "content": "You are a helpful assistant.\n\n# Tools\n\nYou may call one or more functions to assist with the user query.\n\nYou are provided with function signatures within <tools></tools> XML tags:\n<tools>\n{\"type\": \"function\", \"function\": {\"name\": \"headcount\", \"description\": \"Get headcount data for a region by staffing type\", \"parameters\": {\"properties\": {\"staffing_type\": {\"type\": \"str\", \"description\": \"The staffing type like contract, fte or agency\"}, \"region\": {\"type\": \"str\", \"description\": \"the geographical region for which you want headcount data.\"}}, \"required\": [\"staffing_type\", \"region\"]}}}\n</tools>\n\nFor each function call, return a json object with function name and arguments within <tool_call></tool_call> XML tags:\n<tool_call>\n{\"name\": <function-name>, \"arguments\": <args-json-object>}\n</tool_call>"
+        },
+        { "role": "user", "content": "tell me about headcount data" },
+        {
+          "role": "assistant",
+          "content": "The \"headcount\" tool provides information about the number of employees in a specific region based on the type of staffing used. It requires two parameters: \"staffing_type\" and \"region\". The \"staffing_type\" parameter specifies the type of staffing, such as contract, full-time equivalent (fte), or agency. The \"region\" parameter specifies the geographical region for which you want headcount data."
+        },
+        { "role": "user", "content": "europe and for fte" }
+      ]
+      "#;
+
+      let messages: Vec<Message> = serde_json::from_str(test_str).unwrap();
+      let messages_for_halluncination = extract_messages_for_hallucination(&messages);
+      assert_eq!(messages_for_halluncination.len(), 2);
+    }
+}