fix: handle empty inputs in CircleSort (TheAlgorithms#5121)

* fix: handle empty inputs in `CircleSort`

* style: remove `main` method

Author: vil02

src/main/java/com/thealgorithms/sorts/CircleSort.java

@@ -10,6 +10,9 @@ public class CircleSort implements SortAlgorithm {
     @Override
     public <T extends Comparable<T>> T[] sort(T[] array) {
         int n = array.length;
+        if (n == 0) {
+            return array;
+        }
         while (doSort(array, 0, n - 1)) {
         }
         return array;
@@ -50,21 +53,4 @@ private <T extends Comparable<T>> Boolean doSort(T[] array, int left, int right)
 
         return swapped || leftHalf || rightHalf;
     }
-
-    /* Driver code*/
-    public static void main(String[] args) {
-        CircleSort CSort = new CircleSort();
-
-        Integer[] arr = {4, 23, 6, 78, 1, 54, 231, 9, 12};
-        CSort.sort(arr);
-        for (int i = 0; i < arr.length - 1; ++i) {
-            assert arr[i] <= arr[i + 1];
-        }
-
-        String[] stringArray = {"c", "a", "e", "b", "d"};
-        CSort.sort(stringArray);
-        for (int i = 0; i < stringArray.length - 1; ++i) {
-            assert arr[i].compareTo(arr[i + 1]) <= 0;
-        }
-    }
 }

src/test/java/com/thealgorithms/sorts/CircleSortTest.java

@@ -0,0 +1,8 @@
+package com.thealgorithms.sorts;
+
+class CircleSortTest extends SortingAlgorithmTest {
+    @Override
+    SortAlgorithm getSortAlgorithm() {
+        return new CircleSort();
+    }
+}