class_docstr: Unit tests for Agent class
code: def agent(self, sample_df: pd.DataFrame, config: dict) -> Agent:
      return Agent(sample_df, config)
  
imports: from typing import Optional
  from unittest.mock import Mock
  from pandasai.agent import Agent
  import pandas
  import pytest
  from pandasai.llm.fake import FakeLLM
  from pandasai.prompts.clarification_questions_prompt import ClarificationQuestionPrompt
  from pandasai.prompts.explain_prompt import ExplainPrompt
  from pandasai.smart_datalake import SmartDatalake
label_desc: Use image node_id 4 for calling the TestAgent obj's underlying member method code with example usage: obj.agent(sample_df, config) and returns: Agent