added initial test suite and fixed pytest env problems

tests/conftest.py

@@ -0,0 +1,62 @@
+"""Pytest configuration and fixtures."""
+
+import pytest
+import sys
+import os
+
+# Add src directory to path for imports
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'src'))
+
+
+@pytest.fixture
+def mock_tkinter_root():
+    """Create a mock Tkinter root window for GUI tests."""
+    import unittest.mock
+    return unittest.mock.MagicMock()
+
+
+@pytest.fixture(autouse=True)
+def mock_tkinter_imports():
+    """Mock tkinter imports to avoid GUI dependencies in tests."""
+    import unittest.mock
+    
+    # Mock tkinter modules
+    mock_tk = unittest.mock.MagicMock()
+    mock_messagebox = unittest.mock.MagicMock()
+    mock_filedialog = unittest.mock.MagicMock()
+    
+    modules_to_mock = {
+        'tkinter': mock_tk,
+        'tkinter.messagebox': mock_messagebox,
+        'tkinter.filedialog': mock_filedialog,
+        'tkinter.ttk': unittest.mock.MagicMock(),
+    }
+    
+    with unittest.mock.patch.dict('sys.modules', modules_to_mock):
+        yield
+
+
+@pytest.fixture
+def temp_directory():
+    """Create a temporary directory for testing."""
+    import tempfile
+    import shutil
+    
+    temp_dir = tempfile.mkdtemp()
+    yield temp_dir
+    shutil.rmtree(temp_dir)
+
+
+@pytest.fixture
+def temp_file():
+    """Create a temporary file for testing."""
+    import tempfile
+    import os
+    
+    fd, temp_path = tempfile.mkstemp()
+    os.close(fd)
+    yield temp_path
+    try:
+        os.unlink(temp_path)
+    except FileNotFoundError:
+        pass