Flutter how testing registration code input by Integration test

Question

I use pinput for check registration code by send email code in register. I have problem in integration test in enter registration code, because testing doesn't know correct code.

code

      // register email request success test
      await registerTest.enterEmail("example@email.com");
      await registerTest.onTapContinueButton(true);
      expect(loadingOverlay, findsOneWidget);
      await tester.pump(const Duration(seconds: 1));
      expect(bottomInfoSnackbar, findsOneWidget);
      await tester.pump();

      // enter verification code
      await registerTest.enterVerificationCode("1234");
      await tester.pump();
      expect(bottomInfoSnackbar, findsOneWidget);
      await tester.pumpAndSettle();