Integer array incrementer

Incrementer.java

public class Incrementer {
    public static int[] increment(int[] input) {
        int index = input.length -1;
        while(++input[index] % 10 == 0) {
            input[index] = input[index] % 10;
            if(index == 0) {
                int[] result = new int[input.length + 1];
                result[0] = 1;
                return result;
            }
            index--;
        }
        return input;
    }
}

IncrementerTest.java

public class IncrementerTest extends TestCase {

    public void test_incrementSingleFromZero() {
        assertEquals(new int[] { 1 }, Incrementer.increment(new int[] { 0 }));
    }

    public void test_incrementSingleFromNine() {
        assertEquals(new int[] { 1, 0 }, Incrementer.increment(new int[] { 9 }));
    }

}