Use import-mode=importlib

pyproject.toml

@@ -54,6 +54,7 @@ minversion = "7.0"
 addopts = """
 --strict-config
 --strict-markers
+--import-mode=importlib
 -ra
 -v
 -m 'not externalfile'

tests/conftest.py

@@ -2,13 +2,17 @@
 # Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
 
 import os
+import sys
+from pathlib import Path
 from typing import Any, List
 
 import pytest
 import scipp as sc
 
 # Silence warning from Jupyter
 os.environ['JUPYTER_PLATFORM_DIRS'] = '1'
+# To import helper modules
+sys.path.insert(0, str(Path(__file__).resolve().parent))
 
 pytest.register_assert_rewrite('scipp.testing.assertions')
 

tests/load_files_test.py

@@ -2,13 +2,12 @@
 # Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
 from typing import Any, Dict, Optional, Union
 
+import externalfile
 import pytest
 import scipp as sc
 
 import scippnexus as snx
 
-externalfile = pytest.importorskip('externalfile')
-
 all_files = [
     '2023/DREAM_baseline_all_dets.nxs',
     '2023/BIFROST_873855_00000015.hdf',