Sorted Linked List Added (#5519)

* Sorted Linked List added with Javadoc and tests

* "Added comments to SortedLinkedList.java to describe the implementation and provide a reference link."

* Upgraded test from junit 4 to junit 5

* Added space before braces of functions

* Rename SortedlinkedListTest.java to SortedLinkedListTest.java

* made to string null safe

* Updated tail

* "Added assignment of `this.tail` to `newNode` in `SortedLinkedList` class."

* Remove assertions for minValue and maxValue in empty list test

* tried to get link updated

* "Fixed whitespace and formatting issues in SortedLinkedList.java and SortedLinkedListTest.java"

* formatting of test file corrected

* Removed few whitespaces

* Addressed comments by alxkm

* "Updated toString method to include brackets and removed default Node constructor."

* tests updated

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

@@ -0,0 +1,67 @@
+package com.thealgorithms.datastructures.lists;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+public class SortedLinkedListTest {
+
+    @Test
+    public void testInsert() {
+        SortedLinkedList list = new SortedLinkedList();
+        list.insert(5);
+        list.insert(3);
+        list.insert(7);
+        assertEquals("[3, 5, 7]", list.toString());
+    }
+
+    @Test
+    public void testDelete() {
+        SortedLinkedList list = new SortedLinkedList();
+        list.insert(5);
+        list.insert(3);
+        list.insert(7);
+        assertTrue(list.delete(5));
+        assertEquals("[3, 7]", list.toString());
+        assertFalse(list.delete(10));
+    }
+
+    @Test
+    public void testSearch() {
+        SortedLinkedList list = new SortedLinkedList();
+        list.insert(5);
+        list.insert(3);
+        list.insert(7);
+        assertTrue(list.search(5));
+        assertFalse(list.search(10));
+    }
+    @Test
+    public void testEmptyList() {
+        SortedLinkedList list = new SortedLinkedList();
+        assertEquals("[]", list.toString());
+        assertFalse(list.delete(5));
+        assertFalse(list.search(5));
+    }
+    @Test
+    public void testIsEmptyOnEmptyList() {
+        SortedLinkedList list = new SortedLinkedList();
+        assertTrue(list.isEmpty());
+    }
+
+    @Test
+    public void testIsEmptyOnNonEmptyList() {
+        SortedLinkedList list = new SortedLinkedList();
+        list.insert(10);
+        assertFalse(list.isEmpty());
+    }
+
+    @Test
+    public void testIsEmptyAfterDeletion() {
+        SortedLinkedList list = new SortedLinkedList();
+        list.insert(10);
+        list.delete(10);
+        assertTrue(list.isEmpty());
+    }
+}