feat(server): refactor copilot (#14892)

#### PR Dependency Tree


* **PR #14892** 👈

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packages/backend/native/src/llm/tests.rs

@@ -0,0 +1,94 @@
+use llm_adapter::backend::{BackendRequestLayer, ChatProtocol};
+use napi::{Status, Task};
+
+use super::AsyncLlmDispatchPreparedTask;
+use crate::llm::{map_json_error, parse_protocol, resolve_request_chain, resolve_stream_chain};
+
+#[test]
+fn should_parse_supported_protocol_aliases() {
+  assert!(parse_protocol("openai_chat").is_ok());
+  assert!(parse_protocol("chat-completions").is_ok());
+  assert!(parse_protocol("responses").is_ok());
+  assert!(parse_protocol("anthropic").is_ok());
+  assert!(parse_protocol("gemini").is_ok());
+}
+
+#[test]
+fn should_reject_unsupported_protocol() {
+  let error = parse_protocol("unknown").unwrap_err();
+  assert_eq!(error.status, Status::InvalidArg);
+  assert!(error.reason.contains("unsupported chat protocol"));
+}
+
+#[test]
+fn llm_dispatch_prepared_should_reject_invalid_routes_json() {
+  let mut task = AsyncLlmDispatchPreparedTask {
+    routes_json: "{".to_string(),
+  };
+  let error = task.compute().unwrap_err();
+  assert_eq!(error.status, Status::InvalidArg);
+  assert!(error.reason.contains("Invalid JSON payload"));
+}
+
+#[test]
+fn map_json_error_should_use_invalid_arg_status() {
+  let parse_error = serde_json::from_str::<serde_json::Value>("{").unwrap_err();
+  let error = map_json_error(parse_error);
+  assert_eq!(error.status, Status::InvalidArg);
+  assert!(error.reason.contains("Invalid JSON payload"));
+}
+
+#[test]
+fn resolve_request_chain_should_support_clamp_max_tokens() {
+  let chain = resolve_request_chain(
+    &["normalize_messages".to_string(), "clamp_max_tokens".to_string()],
+    ChatProtocol::OpenaiChatCompletions,
+    None,
+  )
+  .unwrap();
+  assert_eq!(chain.len(), 2);
+}
+
+#[test]
+fn resolve_request_chain_should_support_openai_request_compat() {
+  let chain = resolve_request_chain(
+    &["openai_request_compat".to_string()],
+    ChatProtocol::OpenaiChatCompletions,
+    None,
+  )
+  .unwrap();
+  assert_eq!(chain.len(), 1);
+}
+
+#[test]
+fn resolve_request_chain_should_reject_unknown_middleware() {
+  let error = resolve_request_chain(&["unknown".to_string()], ChatProtocol::OpenaiChatCompletions, None).unwrap_err();
+  assert_eq!(error.status, Status::InvalidArg);
+  assert!(error.reason.contains("unsupported request middleware"));
+}
+
+#[test]
+fn resolve_request_chain_should_use_request_layer_defaults() {
+  let chain = resolve_request_chain(
+    &[],
+    ChatProtocol::OpenaiChatCompletions,
+    Some(BackendRequestLayer::ChatCompletions),
+  )
+  .unwrap();
+  assert_eq!(chain.len(), 2);
+
+  let chain = resolve_request_chain(
+    &[],
+    ChatProtocol::GeminiGenerateContent,
+    Some(BackendRequestLayer::GeminiApi),
+  )
+  .unwrap();
+  assert_eq!(chain.len(), 2);
+}
+
+#[test]
+fn resolve_stream_chain_should_reject_unknown_middleware() {
+  let error = resolve_stream_chain(&["unknown".to_string()]).unwrap_err();
+  assert_eq!(error.status, Status::InvalidArg);
+  assert!(error.reason.contains("unsupported stream middleware"));
+}