Arabic to Roman

src_Ruler.java

/**
 * Created by thiago on 12/04/15.
 */
public class Ruler {
    String[] indexRomans = {"M", "D", "C", "L", "X", "V", "I"};
       int[] indexArabic = {1000, 500, 100, 50, 10, 5, 1};

    public String convertToRoman(int number){
        String result = "";
        int index = 0;
        // find index
        while (indexArabic[index] <= number) {
            index++;
        }

        while (number >= indexArabic[index]) {
            result += indexRomans[index];
            number -= indexArabic[index];
        }


        return result;
    }
}

test_RulerTest.java

import org.junit.Test;

import static org.junit.Assert.assertEquals;

public class RulerTest {

    @Test
    public void TestRetornaIVQuandoRecebe4(){
        Ruler arabic = new Ruler();
        String roman = arabic.convertToRoman(4);
        assertEquals("IV", roman);
    }

    @Test
    public void TestRetornaIVQuandoRecebe5(){
        Ruler arabic = new Ruler();
        String roman = arabic.convertToRoman(5);
        assertEquals("V", roman);
    }

}