class_docstr: Unit tests for Agent class
code: def test_clarification_prompt_validate_output_false_case(
      self, agent: Agent
  ):
      # Test whether the output is json or not
      agent._lake.llm.call = Mock()
      agent._lake.llm.call.return_value = "This is not json"
  
      prompt = ClarificationQuestionPrompt(
          dataframes=agent._lake.dfs,
          conversation="test conversation",
          query="test query",
      )
      with pytest.raises(Exception):
          agent._call_llm_with_prompt(prompt)
  
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 19 for calling the TestAgent obj's underlying member method code with example usage: obj.test_clarification_prompt_validate_output_false_case(agent) without return types