feat: GenAI Client(evals): Apply default user persona 'Evaluator' in multi-turn agent scraping

PiperOrigin-RevId: 895988271

Author: vertex-sdk-bot

tests/unit/vertexai/genai/test_evals.py

@@ -5054,7 +5054,9 @@ async def test_run_adk_user_simulation_success(
         assert turn["events"][1]["content"] == {"text": "agent msg"}
 
         mock_scenario_cls.assert_called_once_with(
-            starting_prompt="start", conversation_plan="plan"
+            starting_prompt="start",
+            conversation_plan="plan",
+            user_persona="EVALUATOR",
         )
         mock_session_input_cls.assert_called_once()
 
@@ -5113,7 +5115,9 @@ async def test_run_adk_user_simulation_missing_session_inputs(
         await _evals_common._run_adk_user_simulation(row, mock_agent)
 
         mock_scenario_cls.assert_called_once_with(
-            starting_prompt="start", conversation_plan="plan"
+            starting_prompt="start",
+            conversation_plan="plan",
+            user_persona="EVALUATOR",
         )
         mock_session_input_cls.assert_called_once_with(
             app_name="user_simulation_app",

vertexai/_genai/_evals_common.py

@@ -959,6 +959,7 @@ async def _run_adk_user_simulation(
     """Runs a multi-turn user simulation using ADK's EvaluationGenerator."""
     starting_prompt = row.get("starting_prompt")
     conversation_plan = row.get("conversation_plan")
+    user_persona = "EVALUATOR"
 
     if not starting_prompt or not conversation_plan:
         raise ValueError(
@@ -967,7 +968,9 @@ async def _run_adk_user_simulation(
         )
 
     scenario = ConversationScenario(
-        starting_prompt=starting_prompt, conversation_plan=conversation_plan
+        starting_prompt=starting_prompt,
+        conversation_plan=conversation_plan,
+        user_persona=user_persona,
     )
 
     user_simulator_kwargs: dict[str, Any] = {}