How to write test for an endpoint requiring user input?

I have an endpoint /verification which depends on a alphanumeric code(otp) sent on user's mobile. The code is generated and verified by third party via my api.

func TestVerification(t *testing.T) {

     sendAlphaNumCode() //this sends code
    req, err := http.NewRequest("POST", "/verification", bytes.NewBuffer([]byte(`{"code":"AXY98T"}`))) //code here is dynamic
    //error handling

    rr := httptest.NewRecorder()
    handler := http.HandlerFunc(Verify)
    handler.ServeHTTP(rr, req)

    //assertions here

}

I am posting from mobile, so I could not copy paste the whole code

I can not take input from console as it's set to /dev/null by golang while testing.

1. Is there any way I can make golang tests wait for my input?
2. Is mocking third party, the only way. If no, how else should I go about that?

I care about testing it in a functional way, if possible with third party api. preferably in golang. Every input is welcome.

I always accept answer Leave a comment for more clarity.