Enhance docs, remove main, add tests in `SearchSinglyLink… (#6012)

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

@@ -0,0 +1,89 @@
+package com.thealgorithms.datastructures.lists;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class SearchSinglyLinkedListRecursionTest {
+
+    private SearchSinglyLinkedListRecursion list;
+
+    @BeforeEach
+    public void setUp() {
+        list = new SearchSinglyLinkedListRecursion();
+    }
+
+    @Test
+    public void testSearchInEmptyList() {
+        // Test searching for a value in an empty list (should return false)
+        assertFalse(list.search(1));
+    }
+
+    @Test
+    public void testSearchSingleElementListFound() {
+        // Insert a single element and search for it
+        list.insert(5);
+        assertTrue(list.search(5));
+    }
+
+    @Test
+    public void testSearchSingleElementListNotFound() {
+        // Insert a single element and search for a non-existent value
+        list.insert(5);
+        assertFalse(list.search(10));
+    }
+
+    @Test
+    public void testSearchMultipleElementsListFound() {
+        // Insert multiple elements and search for a middle value
+        for (int i = 1; i <= 10; i++) {
+            list.insert(i);
+        }
+        assertTrue(list.search(5));
+    }
+
+    @Test
+    public void testSearchMultipleElementsListFirstElement() {
+        // Insert multiple elements and search for the first element
+        for (int i = 1; i <= 10; i++) {
+            list.insert(i);
+        }
+        assertTrue(list.search(1));
+    }
+
+    @Test
+    public void testSearchMultipleElementsListLastElement() {
+        // Insert multiple elements and search for the last element
+        for (int i = 1; i <= 10; i++) {
+            list.insert(i);
+        }
+        assertTrue(list.search(10));
+    }
+
+    @Test
+    public void testSearchMultipleElementsListNotFound() {
+        // Insert multiple elements and search for a non-existent element
+        for (int i = 1; i <= 10; i++) {
+            list.insert(i);
+        }
+        assertFalse(list.search(15));
+    }
+
+    @Test
+    public void testSearchNegativeValues() {
+        // Insert positive and negative values and search for a negative value
+        list.insert(-5);
+        list.insert(-10);
+        list.insert(5);
+        assertTrue(list.search(-10));
+        assertFalse(list.search(-3));
+    }
+
+    @Test
+    public void testSearchZeroValue() {
+        list.insert(0);
+        assertTrue(list.search(0));
+    }
+}