code: def discover_single_case(self, module, case_attributes):
          
          # Find single case
          case = module
          loader = self._loader
          for index, component in enumerate(case_attributes):
              case = getattr(case, component, None)
              if case is None:
                  return loader.create_suite()
              elif loader.is_test_case(case):
                  rest = case_attributes[index + 1:]
                  if len(rest) > 1:
                      raise ValueError('Too many components in module path')
                  elif len(rest) == 1:
                      return loader.create_suite(
                          [loader.load_test(case, *rest)])
                  return loader.load_case(case)
  
          # No cases matched, return empty suite
          return loader.create_suite()
docs: Find and load a single TestCase or TestCase method from a module.
  
          Parameters
          ----------
          module : module
              The imported Python module containing the TestCase to be
              loaded.
          case_attributes : list
              A list (length 1 or 2) of str.  The first component must be
              the name of a TestCase subclass.  The second component must
              be the name of a method in the TestCase.