Add: BinaryTreePathsTest.java for unit testing

Author: konduri-lakshmi-prasanna

src/test/java/com/thealgorithms/backtracking/BinaryTreePathsTest.java

@@ -0,0 +1,41 @@
+package com.thealgorithms.backtracking;
+
+import org.junit.jupiter.api.Test;
+import java.util.List;
+import static org.junit.jupiter.api.Assertions.*;
+
+public class BinaryTreePathsTest {
+
+    @Test
+    void testBinaryTreePathsBasic() {
+        BinaryTreePaths.TreeNode root = new BinaryTreePaths.TreeNode(1);
+        root.left = new BinaryTreePaths.TreeNode(2);
+        root.right = new BinaryTreePaths.TreeNode(3);
+        root.left.right = new BinaryTreePaths.TreeNode(5);
+
+        BinaryTreePaths solver = new BinaryTreePaths();
+        List<String> result = solver.binaryTreePaths(root);
+
+        assertEquals(2, result.size());
+        assertTrue(result.contains("1->2->5"));
+        assertTrue(result.contains("1->3"));
+    }
+
+    @Test
+    void testSingleNodeTree() {
+        BinaryTreePaths.TreeNode root = new BinaryTreePaths.TreeNode(42);
+
+        BinaryTreePaths solver = new BinaryTreePaths();
+        List<String> result = solver.binaryTreePaths(root);
+
+        assertEquals(List.of("42"), result);
+    }
+
+    @Test
+    void testEmptyTree() {
+        BinaryTreePaths solver = new BinaryTreePaths();
+        List<String> result = solver.binaryTreePaths(null);
+
+        assertTrue(result.isEmpty());
+    }
+}