add basic functionality and corresponding tests

tests/conftest.py

@@ -0,0 +1,12 @@
+from pathlib import Path
+
+import pytest
+
+
+@pytest.fixture(scope="session")
+def root_data_folder() -> Path:
+    pth = Path.cwd() / "tests/_test_data/"
+    assert pth.exists()
+    assert pth.is_dir()
+
+    return pth