import static org.junit.jupiter.api.Assertions.$*$;

import org.junit.jupiter.api.Test;

public class RecursionTest $\{$

@Test

public void testFactorial$()\{$

assertEquals$(1,$ Recursion.factorial$(0))$;

assertEquals$(1,$ Recursion.factorial$(1))$;

assertEquals$(2,$ Recursion.factorial$(2))$;

assertEquals$(6,$ Recursion.factorial$(3))$;

assertEquals$(24,$ Recursion.factorial$(4))$;

assertEquals$(120,$ Recursion.factorial$(5))$;

$\}$

@Test

public void testSumOfDigits$()\{$

assertEquals$(0,$ Recursion.sumOfDigits$(0))$;

assertEquals$(4,$ Recursion.sumOfDigits$(4))$;

assertEquals$(10,$ Recursion.sumOfDigits$(1234))$;

assertEquals$(15,$ Recursion.sumOfDigits$(555))$;

$\}$

@Test

public void testGreatestCommonDivisor$()\{$

assertEquals$(6,$ Recursion.greatestCommonDivisor$(54,24))$;

assertEquals$(6,$ Recursion.greatestCommonDivisor$(54,-24))$;

assertEquals$(6,$ Recursion.greatestCommonDivisor$(-54,24))$;

assertEquals$(6,$ Recursion.greatestCommonDivisor$(-54,-24))$;

assertEquals$(14,$ Recursion.greatestCommonDivisor$(42,56))$;

assertEquals$(21,$ Recursion.greatestCommonDivisor$(1071,462))$;

$\}$

@Test

public void testIsPalindrome$()\{$

assertTrue$($Recursion$.$isPalindrome$("$racecar$"))$;

assertTrue$($Recursion$.$isPalindrome$("$noon$"))$;

assertFalse$($Recursion$.$isPalindrome$("$java$"))$;

assertFalse$($Recursion$.$isPalindrome$("$recursion$"))$;

assertTrue$($Recursion$.$isPalindrome$("$a$"))$;

assertTrue$($Recursion$.$isPalindrome$(""))$;

$\}$

$\}$