def test_oneTransition(self):
        """
        L{Automaton.addTransition} adds its input symbol to
        L{Automaton.inputAlphabet}, all its outputs to
        L{Automaton.outputAlphabet}, and causes L{Automaton.outputForInput} to
        start returning the new state and output symbols.
        """
        a = Automaton()
        a.addTransition("beginning", "begin", "ending", ["end"])
        self.assertEqual(a.inputAlphabet(), {"begin"})
        self.assertEqual(a.outputAlphabet(), {"end"})
        self.assertEqual(a.outputForInput("beginning", "begin"),
                         ("ending", ["end"]))
        self.assertEqual(a.states(), {"beginning", "ending"})

        L{Automaton.addTransition} adds its input symbol to
        L{Automaton.inputAlphabet}, all its outputs to
        L{Automaton.outputAlphabet}, and causes L{Automaton.outputForInput} to
        start returning the new state and output symbols.
        
stackoverflow/venv/lib/python3.6/site-packages/automat/_test/test_core.py