fix(langchain): add role to plain completions

Author: ianchi

packages/opentelemetry-instrumentation-langchain/opentelemetry/instrumentation/langchain/span_utils.py

@@ -269,7 +269,10 @@ def set_chat_response(span: Span, response: LLMResult) -> None:
                 )
                 if tool_calls and isinstance(tool_calls, list):
                     _set_chat_tool_calls(span, prefix, tool_calls)
-
+            else:
+                _set_span_attribute(
+                    span, f"{prefix}.role", "assistant"
+                )
             i += 1
 
 

packages/opentelemetry-instrumentation-langchain/tests/test_span_utils.py

@@ -82,5 +82,5 @@ def test_plain_generation_defaults_to_assistant_role():
     set_chat_response(span, result)
 
     prefix = f"{GenAIAttributes.GEN_AI_COMPLETION}.0"
-    assert prefix + ".role" not in span.attributes
+    assert prefix + ".role" == "assistant"
     assert span.attributes[prefix + ".content"] == "plain completion"