diff --git a/tests/test_flagController.py b/tests/test_flagController.py
index 11a844e..97f2d30 100644
--- a/tests/test_flagController.py
+++ b/tests/test_flagController.py
@@ -1,7 +1,10 @@
 import pytest
-from unittest.mock import patch, MagicMock
+import os
+from pathlib import Path
+from unittest.mock import patch, MagicMock, mock_open
 from twinTrim.flagController import handleAllFlag
 from twinTrim.dataStructures.fileFilter import FileFilter
+from twinTrim.flagController import find_duplicates
 
 @patch('os.walk')
 @patch('twinTrim.flagController.add_or_update_file')
@@ -70,3 +73,67 @@ def test_handle_all_flag_success(mock_progress_bar, mock_add_or_update_file, moc
     # Assertions
     assert mock_add_or_update_file.call_count == 3  # All 3 files should be processed
     mock_progress_bar.assert_called_once()  # Progress bar should still be created
+
+
+def count_files(directory):
+    if not isinstance(directory, (str, Path)):
+        raise TypeError("Directory path must be a string or Path object")
+        
+    if not os.path.exists(directory):
+        raise FileNotFoundError(f"Directory '{directory}' does not exist")
+        
+    if not os.path.isdir(directory):
+        raise NotADirectoryError(f"'{directory}' is not a directory")
+    
+    total_files = 0
+    for root, _, files in os.walk(directory):
+        total_files += len(files)
+    
+    return total_files
+
+def test_count_files_empty_directory(tmp_path):
+    assert count_files(str(tmp_path)) == 0
+
+def test_count_files_single_file(tmp_path):
+    file_path = tmp_path / "test.txt"
+    file_path.write_text("test content")
+    assert count_files(str(tmp_path)) == 1
+
+def test_count_files_multiple_files(tmp_path):
+    for i in range(3):
+        file_path = tmp_path / f"test{i}.txt"
+        file_path.write_text(f"content {i}")
+    
+    assert count_files(str(tmp_path)) == 3
+
+def test_count_files_with_subdirectories(tmp_path):
+    (tmp_path / "file1.txt").write_text("content")
+    (tmp_path / "file2.txt").write_text("content")
+    
+    subdir = tmp_path / "subdir"
+    subdir.mkdir()
+    (subdir / "file3.txt").write_text("content")
+    (subdir / "file4.txt").write_text("content")
+    
+    assert count_files(str(tmp_path)) == 4
+
+def test_count_files_nonexistent_directory():
+    with pytest.raises(FileNotFoundError):
+        count_files("/nonexistent/directory")
+
+def test_count_files_invalid_input():
+    with pytest.raises(TypeError):
+        count_files(123)
+
+def test_count_files_file_as_input(tmp_path):
+    file_path = tmp_path / "test.txt"
+    file_path.write_text("test content")
+    
+    with pytest.raises(NotADirectoryError):
+        count_files(str(file_path))
+
+def test_count_files_with_hidden_files(tmp_path):
+    (tmp_path / "visible.txt").write_text("content")
+    (tmp_path / ".hidden").write_text("content")
+    
+    assert count_files(str(tmp_path)) == 2
\ No newline at end of file