docstr: Test that None is returned by the find method
  when a matching statement is not found.
docstr_tok: ["Test","that","None","is","returned","by","the","find","method","when","a","matching","statement","is","not","found","."]
code: def test_filter_statement_not_found(self):
      """
      Test that None is returned by the find method
      when a matching statement is not found.
      """
      results = list(self.adapter.filter(text="Non-existant"))
      self.assertEqual(len(results), 0)
  
imports: from django.test import TestCase
  from chatterbot.storage import DjangoStorageAdapter
  from chatterbot.conversation import Statement
  from chatterbot.ext.django_chatterbot.models import Statement
label_desc: Use image node_id 3 for calling the DjangoStorageAdapterTests obj's underlying member method code with example usage: obj.test_filter_statement_not_found() without return types