Merge pull request #13549 from sam-gardner/BAEL-5836-Moving-items-in-an-arraylist

BAEL-5836 Add unit tests for moving items in an arraylist

core-java-modules/core-java-collections-list-5/src/test/java/com/baeldung/java/list/MovingItemsInArrayListUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.java.list;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+
+import org.junit.Test;
+
+public class MovingItemsInArrayListUnitTest {
+
+    @Test
+    public void givenAList_whenManuallyReordering_thenOneItemMovesPosition() {
+        ArrayList<String> arrayList = new ArrayList<>(Arrays.asList("one", "two", "three", "four", "five"));
+
+        String removed = arrayList.remove(3);
+        arrayList.add(2, removed);
+
+        ArrayList<String> expectedResult = new ArrayList<>(Arrays.asList("one", "two", "four", "three", "five"));
+        assertEquals(expectedResult, arrayList);
+    }
+
+    @Test
+    public void givenAList_whenUsingSwap_thenItemsSwapPositions() {
+        ArrayList<String> arrayList = new ArrayList<>(Arrays.asList("one", "two", "three", "four", "five"));
+
+        Collections.swap(arrayList, 1, 3);
+
+        ArrayList<String> expectedResult = new ArrayList<>(Arrays.asList("one", "four", "three", "two", "five"));
+        assertEquals(expectedResult, arrayList);
+    }
+
+    @Test
+    public void givenAList_whenUsingRotateWithPositiveDistance_thenItemsMoveToTheRight() {
+        ArrayList<String> arrayList = new ArrayList<>(Arrays.asList("one", "two", "three", "four", "five"));
+
+        Collections.rotate(arrayList, 2);
+
+        ArrayList<String> expectedResult = new ArrayList<>(Arrays.asList("four", "five", "one", "two", "three"));
+        assertEquals(expectedResult, arrayList);
+    }
+
+    @Test
+    public void givenAList_whenUsingRotateWithNegativeDistance_thenItemsMoveToTheLeft() {
+        ArrayList<String> arrayList = new ArrayList<>(Arrays.asList("one", "two", "three", "four", "five"));
+
+        Collections.rotate(arrayList, -2);
+
+        ArrayList<String> expectedResult = new ArrayList<>(Arrays.asList("three", "four", "five", "one", "two"));
+        assertEquals(expectedResult, arrayList);
+    }
+}