code: def test_exception_class_fallback(self):
      cur = self.conn.cursor()
  
      x = sqlstate_errors.pop("42P01")
      try:
          cur.execute("select * from nonexist")
      except psycopg2.Error as exc:
          e = exc
      finally:
          sqlstate_errors["42P01"] = x
  
      self.assertEqual(type(e), self.conn.ProgrammingError)
  
file_path: psycopg2/tests/test_errors.py
imports: import unittest
  from .testutils import ConnectingTestCase
  import psycopg2
  from psycopg2 import errors
  from psycopg2._psycopg import sqlstate_errors
  from psycopg2.errors import UndefinedTable
label_desc: Use image node_id 2 for calling the ErrorsTests obj's underlying member method code with example usage: obj.test_exception_class_fallback() without return types