How to write a JUnit when the values I wanna test come from user input? [duplicate]

This question already has an answer here:

• JUnit test for console input and output 1 answer
• junit testing for user input using Scanner 4 answers

I have a homework on testing and I am asked to implement a test class for the following code, which was given to us from our teacher:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Test {
static double value;
static double output;
static double multiplyWith;

public static void main(String[] args) {
    // TODO Auto-generated method stub
    BufferedReader in = 
            new BufferedReader(new InputStreamReader(System.in));
     System.out.println("Enter a value between 2 and 11");
     try {
          value = Double.parseDouble(in.readLine());
        } catch (NumberFormatException e1) {
            e1.printStackTrace();
        } catch (IOException e1) {
            e1.printStackTrace();
        }
     if(value<2 || value > 11) {
         System.out.println("Wrong input, please restart");
         System.exit(-1);
     }

     System.out.println("With which positive digit would you like to multiply your input in case it can be divided by 2 ?");
     try {
            String s = in.readLine();
            multiplyWith  = Integer.valueOf(s).intValue();
        } catch (IOException e) {
            e.printStackTrace();
        }
//check if value is positive
       if (multiplyWith <= 0) {
          System.out.println("Please restart and input a positive number");
          System.exit (-1);
          }
//       compute output

     if (value % 2 == 0.0) {
         output = value*multiplyWith; }
     else        {
         output = value;
     }

     System.out.println ("Your result is " + output);
  }

 }

My question is how can I test the above code since it is dependent on the input stream and not on parameters and the output is always printed on runtime? I do not understand how I should test something like this. I would apreciate an explanation not just code, as I want to understand how this works. Thanks in advance!