code: def mock(self, tst_name, tst_type):
          
          print(" -> Mock {tst_name} appear".format(**locals()))
          # Service appears
          self.available[tst_name] = tst_type
          yield
          # Service disappear
          self.available.pop(tst_name)
          print(" -> Mock {tst_name} disappear".format(**locals()))
docs: Mock appearance/disappearance to force changes in interface , via setting local cache.
          :param tst_name:
          :param tst_type:
          :return: