Haven't any experience writing recursive functions.(Generally tend to avoid them - not sure if that's a negative). What do you think about the following?

This is also my first time using JUnit, I'd appreciate input if I'm doing something wrong there.

Challenge: Create a digital Root Function.

Specifications:
A digital root is the recursive sum of all the digits in a number.
Given n, take the sum of the digits of n.
If the resulting value has two digits, continue reducing until a single-digit number is produced.
This is only applicable to the natural numbers.

Solution:

public static int getDigitalRoot(int num) {
 if (Integer.toString(num).length() == 1) { return num; }
 int result = 0;
 for (char c : Integer.toString(num).toCharArray()) {
 result += Character.getNumericValue(c);
 }
 
 return getDigitalRoot(result); 
 }

Tests:

@Test
 public void Tests() {
 assertEquals(6 , Utilities.getDigitalRoot(942));
 assertEquals(7, Utilities.getDigitalRoot(16));
 }

Haven't any experience writing recursive functions.(Generally tend to avoid them - not sure if that's a negative). What do you think about the following?

This is also my first time using JUnit, I'd appreciate input if I'm doing something wrong there.

Challenge: Create a digital Root Function.

Specifications:
A digital root is the recursive sum of all the digits in a number.
Given n, take the sum of the digits of n.
If the resulting value has two digits, continue reducing until a single-digit number is produced.
This is only applicable to the natural numbers.

Solution:

public static int getDigitalRoot(int num) {
 if (Integer.toString(num).length() == 1) { return num; }
 int result = 0;
 for (char c : Integer.toString(num).toCharArray()) {
 result += Character.getNumericValue(c);
 }
 
 return getDigitalRoot(result); 
 }

Tests:

@Test
 public void Tests() {
 assertEquals(6 , Utilities.getDigitalRoot(942));
 assertEquals(7, Utilities.getDigitalRoot(16));
 }