code: def test_candidate_citations(self):
      self.responses["generate_text"] = glm.GenerateTextResponse(
          candidates=[
              {
                  "output": "Hello Google!",
                  "citation_metadata": {
                      "citation_sources": [
                          {
                              "start_index": 6,
                              "end_index": 12,
                              "uri": "https://google.com",
                          }
                      ]
                  },
              }
          ]
      )
      result = text_service.generate_text(prompt="Hi my name is Google")
      self.assertEqual(
          result.candidates[0]["citation_metadata"]["citation_sources"][
              0
          ]["start_index"],
          6,
      )
  
imports: import copy
  import math
  import unittest
  import unittest.mock
  import google.ai.generativelanguage
  from google.generativeai import text
  from google.generativeai import client
  from google.generativeai.types import safety_types
  from google.generativeai.types import model_types
  from absl.testing import absltest
  from absl.testing import parameterized
label_desc: Use image node_id 12 for calling the UnitTests obj's underlying member method code with example usage: obj.test_candidate_citations() without return types