Create MiddleOfLinkedListTest.java

src/test/java/com/thealgorithms/datastructures/lists/MiddleOfLinkedListTest.java

@@ -0,0 +1,52 @@
+package com.thealgorithms.datastructures.lists;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+public class MiddleOfLinkedListTest {
+
+    @Test
+    void testMiddleNodeOddLength() {
+        MiddleOfLinkedList sol = new MiddleOfLinkedList();
+        int[] values = {1, 2, 3, 4, 5};
+        MiddleOfLinkedList.ListNode head = MiddleOfLinkedList.createList(values);
+
+        MiddleOfLinkedList.ListNode middle = sol.middleNode(head);
+
+        assertEquals(3, middle.val);
+    }
+
+    @Test
+    void testMiddleNodeEvenLength() {
+        MiddleOfLinkedList sol = new MiddleOfLinkedList();
+        int[] values = {1, 2, 3, 4, 5, 6};
+        MiddleOfLinkedList.ListNode head = MiddleOfLinkedList.createList(values);
+
+        MiddleOfLinkedList.ListNode middle = sol.middleNode(head);
+
+        assertEquals(4, middle.val);
+    }
+
+    @Test
+    void testMiddleNodeSingleElement() {
+        MiddleOfLinkedList sol = new MiddleOfLinkedList();
+        int[] values = {1};
+        MiddleOfLinkedList.ListNode head = MiddleOfLinkedList.createList(values);
+
+        MiddleOfLinkedList.ListNode middle = sol.middleNode(head);
+
+        assertEquals(1, middle.val);
+    }
+
+    @Test
+    void testMiddleNodeEmptyList() {
+        MiddleOfLinkedList sol = new MiddleOfLinkedList();
+        int[] values = {};
+        MiddleOfLinkedList.ListNode head = MiddleOfLinkedList.createList(values);
+
+        MiddleOfLinkedList.ListNode middle = sol.middleNode(head);
+
+        assertNull(middle);
+    }
+}