clarify a bit

examples/server/server.cpp

@@ -392,7 +392,7 @@ struct server_task_result {
         return false;
     }
     virtual bool is_stop() {
-        // only used by server_task_result_cmpl_final
+        // only used by server_task_result_cmpl_*
         return false;
     }
     virtual int get_index() {

examples/server/tests/unit/test_completion.py

@@ -42,6 +42,7 @@ def test_completion_stream(prompt: str, n_predict: int, re_content: str, n_promp
     })
     content = ""
     for data in res:
+        assert "stop" in data and type(data["stop"]) == bool
         if data["stop"]:
             assert data["timings"]["prompt_n"] == n_prompt
             assert data["timings"]["predicted_n"] == n_predicted