Refactor: adding check to swap method in SortUtils

Author: Alex Klymenko

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

@@ -17,9 +17,11 @@ private SortUtils() {
      * @param <T>   the type of elements in the array
      */
     public static <T> void swap(T[] array, int i, int j) {
-        T temp = array[i];
-        array[i] = array[j];
-        array[j] = temp;
+        if (i != j) {
+            T temp = array[i];
+            array[i] = array[j];
+            array[j] = temp;
+        }
     }
 
     /**

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

@@ -1,10 +1,17 @@
 package com.thealgorithms.sorts;
 
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.List;
+import java.util.stream.Stream;
+
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
 
 class SortUtilsTest {
 
@@ -67,4 +74,24 @@ void isSortedListFalse() {
         List<Integer> array3 = List.of(5, 4, 3, 2, 1);
         assertFalse(SortUtils.isSorted(array3));
     }
+
+    @ParameterizedTest
+    @MethodSource("provideArraysForSwap")
+    public <T> void testSwap(T[] array, int i, int j, T[] expected, String message) {
+        SortUtils.swap(array, i, j);
+        assertArrayEquals(expected, array, message);
+    }
+
+    private static Stream<Arguments> provideArraysForSwap() {
+        return Stream.of(Arguments.of(new Integer[]{1, 2, 3, 4}, 1, 2, new Integer[]{1, 3, 2, 4}, "Swapping adjacent elements should work correctly."), Arguments.of(new Integer[]{1, 2, 3, 4}, 0, 3, new Integer[]{4, 2, 3, 1}, "Swapping non-adjacent elements should work correctly."), Arguments.of(new Integer[]{1, 2, 3, 4}, 2, 2, new Integer[]{1, 2, 3, 4}, "Swapping the same index should not change the array."),
+            Arguments.of(new String[]{"a", "b", "c", "d"}, 0, 3, new String[]{"d", "b", "c", "a"}, "Swapping first and last elements should work correctly."), Arguments.of(new String[]{null, "b", "c", null}, 0, 3, new String[]{null, "b", "c", null}, "Swapping null elements should work correctly."), Arguments.of(new Integer[]{}, 0, 0, new Integer[]{}, "Swapping in an empty array should not throw an error."));
+    }
+
+    @Test
+    public void testSwapOutOfBounds() {
+        Integer[] array = {1, 2, 3, 4};
+        assertThrows(ArrayIndexOutOfBoundsException.class, () -> {
+            SortUtils.swap(array, -1, 4);
+        }, "Swapping out of bounds should throw an ArrayIndexOutOfBoundsException.");
+    }
 }