Add tests for PowerSum (#3603)

src/main/java/com/thealgorithms/backtracking/PowerSum.java

@@ -10,25 +10,6 @@ import java.util.Scanner;
  */
 public class PowerSum {
 
-    public static void main(String[] args) {
-        Scanner sc = new Scanner(System.in);
-        System.out.println("Enter the number and the power");
-        int N = sc.nextInt();
-        int X = sc.nextInt();
-        PowerSum ps = new PowerSum();
-        int count = ps.powSum(N, X);
-        //printing the answer.
-        System.out.println(
-            "Number of combinations of different natural number's raised to " +
-            X +
-            " having sum " +
-            N +
-            " are : "
-        );
-        System.out.println(count);
-        sc.close();
-    }
-
     private int count = 0, sum = 0;
 
     public int powSum(int N, int X) {

src/test/java/com/thealgorithms/backtracking/PowerSumTest.java

@@ -0,0 +1,28 @@
+package com.thealgorithms.backtracking;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+public class PowerSumTest {
+
+    @Test
+    void testNumberZeroAndPowerZero() {
+        PowerSum powerSum = new PowerSum();
+        int result = powerSum.powSum(0, 0);
+        assertEquals(1, result);
+    }
+
+    @Test
+    void testNumberHundredAndPowerTwo() {
+        PowerSum powerSum = new PowerSum();
+        int result = powerSum.powSum(100, 2);
+        assertEquals(3, result);
+    }
+  
+    @Test
+    void testNumberHundredAndPowerThree() {
+        PowerSum powerSum = new PowerSum();
+        int result = powerSum.powSum(100, 3);
+        assertEquals(1, result);
+    }
+    
+}