diff --git a/test/dir_API.cpp b/test/dir_API.cpp
index 283dd04..1f5d4e0 100644
--- a/test/dir_API.cpp
+++ b/test/dir_API.cpp
@@ -9,6 +9,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <gtest/gtest.h>
+#include <iostream>
 #include "fs.h"
 #include "direntry.h"
 
@@ -17,6 +18,20 @@ const char* d;
 //global can be taken
 TreeNode *root;
 const char* target_filepath;
+typedef struct file_test{
+    const char* name;
+    file_test* next;//use linked-list to know the file at the same level directory
+}file_test;
+typedef struct dir_test{
+    const char* name;
+    file_test*  inFile;
+    dir_test*   subdir;
+    dir_test*   next;//use linked-list to know the other dir at the same parent dir.
+}dir_test;
+
+int total_number = 0;
+int total_free_dir = 0;
+int total_free_file = 0;
 
 const char* get_baseName(const char *filename){
     const char* base_name = strrchr(filename, '/');
@@ -28,6 +43,145 @@ const char* get_baseName(const char *filename){
     return base_name;
 }
 
+const char* generateRandomName(size_t length) {
+    const std::string chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+    std::string randomString;
+
+    for (size_t i = 0; i < length; ++i) {
+        randomString += chars[rand() % chars.size()];
+    }
+
+    // Allocate memory and copy the string
+    char* name = new char[randomString.length() + 1];
+    strcpy(name, randomString.c_str());
+    return name;
+}
+
+// Recursive function to create directory hierarchy
+dir_test* createDirHierarchy(int level, int maxLevel) {
+    if (level > maxLevel) {
+        return nullptr;
+    }
+
+    dir_test* head = nullptr;
+    dir_test* current = nullptr;
+
+    for (int i = 0; i < 3; ++i) {
+        dir_test* newDir = new dir_test;
+        newDir->name = generateRandomName(6); // Generate a random name for the directory
+        newDir->inFile = nullptr; // Initialize file list to nullptr
+        newDir->subdir = createDirHierarchy(level + 1, maxLevel); // Recursively create subdirectories
+        newDir->next = nullptr;
+
+        // Create file list for this directory
+        file_test* fileHead = nullptr;
+        file_test* fileCurrent = nullptr;
+        for (int j = 0; j < 3; ++j) {
+            file_test* newFile = new file_test;
+            newFile->name = generateRandomName(6); // Generate a random name for the file
+            newFile->next = nullptr;
+
+            if (!fileHead) {
+                fileHead = newFile;
+            } else {
+                fileCurrent->next = newFile;
+            }
+            fileCurrent = newFile;
+        }
+        newDir->inFile = fileHead;
+
+        // Add the new directory to the list
+        if (!head) {
+            head = newDir;
+        } else {
+            current->next = newDir;
+        }
+        current = newDir;
+    }
+
+    return head;
+}
+
+// Setup function for the test directory
+void setupTestDirectory(dir_test** root) {
+    fprintf(stderr,"[%s ,%d]\n",__func__,__LINE__);
+    // Allocate memory for root
+    *root = new dir_test;
+    (*root)->name = strdup("/"); // Generate a random name for the directory
+    (*root)->inFile = nullptr; // Initialize file list to nullptr
+    fprintf(stderr,"[%s ,%d]\n",__func__,__LINE__);
+    (*root)->subdir = createDirHierarchy(0, 1);
+    (*root)->next = nullptr;
+    fprintf(stderr,"[%s ,%d]\n",__func__,__LINE__);
+    file_test* fileHead = nullptr;
+    file_test* fileCurrent = nullptr;
+    for (int j = 0; j < 3; ++j) {
+        file_test* newFile = new file_test;
+        newFile->name = generateRandomName(6); // Generate a random name for the file
+        newFile->next = nullptr;
+
+        if (!fileHead) {
+            fileHead = newFile;
+        } else {
+            fileCurrent->next = newFile;
+        }
+        fileCurrent = newFile;
+    }
+    (*root)->inFile = fileHead;
+}
+void setupTestDirectory_1(dir_test** root) {
+
+    *root = createDirHierarchy(0, 1);
+}
+
+// Function to free a list of files
+void freeFileList(file_test* fileList) {
+    while (fileList != nullptr) {
+        file_test* temp = fileList;
+        fileList = fileList->next;
+        total_free_file++;//for debug
+        delete[] temp->name; // Free the name string
+        delete temp; // Free the current file
+    }
+}
+
+// Recursive function to free the directory hierarchy
+void freeDirHierarchy(dir_test* dir) {
+    while (dir != nullptr) {
+        dir_test* temp = dir;
+        dir = dir->next;
+        total_free_dir++;//for debug
+        freeFileList(temp->inFile);  // Free the list of files in the directory
+        freeDirHierarchy(temp->subdir); // Recursively free subdirectories
+        delete[] temp->name; // Free the name string
+        delete temp; // Free the current directory
+    }
+}
+
+// Function to print the list of files in a directory
+void printFileList(const file_test* fileList) {
+    const file_test* currentFile = fileList;
+    while (currentFile != nullptr) {
+        // std::cout << "  File: " << currentFile->name << std::endl;
+        currentFile = currentFile->next;
+    }
+}
+
+void traverseDirHierarchy(const dir_test* dir, int depth = 0) {
+    while (dir != nullptr) {
+        // std::cout << "Depth " << depth << ", Directory: " << dir->name << std::endl;
+        total_number++;//for debug
+
+        // Print files in this directory
+        printFileList(dir->inFile);
+        // Recursively traverse subdirectories
+        traverseDirHierarchy(dir->subdir, depth + 1);
+
+        // Go to the next directory at the same level
+        dir = dir->next;
+    }
+}
+
 TEST(DirTest, root_test) {
     //Init fake root directory
     INode inode_root;
@@ -131,10 +285,23 @@ TEST(DirTest, Add_FindFile_test) {
 }
 
 int main(int argc, char **argv) {
-    d = (argc < 2) ? "/dev/vdc" : argv[1];//how to do with this?
+    srand(time(NULL)); // Seed the random number generator
+    d = (argc < 2) ? "/dev/vdc" : argv[1];
+
+    dir_test* mock_root = nullptr;
+    setupTestDirectory(&mock_root);
+
     ::testing::InitGoogleTest(&argc, argv);
     int result = RUN_ALL_TESTS();
+
+    total_number = 0;
+    traverseDirHierarchy(mock_root);//mock_root
+    printf("Traverse Dir total %d\n",total_number);
+    
     // Cleanup
+    freeDirHierarchy(mock_root);//mock_root
+    printf("Free Dir total %d\n",total_free_dir);
+    printf("Free File total %d\n",total_free_file);
     freeTree(root);
     return result;
 }
\ No newline at end of file