diff --git a/packages/essnmx/tests/conftest.py b/packages/essnmx/tests/conftest.py
index 8710000b..b968fce6 100644
--- a/packages/essnmx/tests/conftest.py
+++ b/packages/essnmx/tests/conftest.py
@@ -2,3 +2,4 @@
 # Copyright (c) 2024 Scipp contributors (https://github.com/scipp)
 # These fixtures cannot be found by pytest,
 # if they are not defined in `conftest.py` under `tests` directory.
+
diff --git a/packages/essnmx/tests/mcstas/mcstas_description_examples.py b/packages/essnmx/tests/mcstas/conftest.py
similarity index 82%
rename from packages/essnmx/tests/mcstas/mcstas_description_examples.py
rename to packages/essnmx/tests/mcstas/conftest.py
index 40315ead..1cac3ffc 100644
--- a/packages/essnmx/tests/mcstas/mcstas_description_examples.py
+++ b/packages/essnmx/tests/mcstas/conftest.py
@@ -1,6 +1,15 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2026 Scipp contributors (https://github.com/scipp)
+# These fixtures are only for mcstas related tests.
+# They are mcstas descriptions to be parsed by essnmx mcstas helper functions.
 # flake8: noqa: E501
 
-no_detectors = """
+import pytest
+
+
+@pytest.fixture
+def no_detectors_desc() -> str:
+    return """
 SPLIT 999 COMPONENT Xtal = Single_crystal(
                 order = 1,
                 p_transmit=0.001,
@@ -23,7 +32,10 @@
 AT (0, 0, deltaz) RELATIVE armSample
 """
 
-two_detectors_two_filenames = """
+
+@pytest.fixture
+def two_detectors_two_filenames_desc() -> str:
+    return """
 COMPONENT nD_Mantid_0 = Monitor_nD(
         options ="mantid square x limits=[0 0.512] bins=1280 y limits=[0 0.512] bins=1280, neutron pixel min=1 t, list all neutrons",
     xmin = 0,
@@ -47,7 +59,10 @@
   ROTATED (0, 90, 0) RELATIVE armSample
 """
 
-one_detector_no_filename = """
+
+@pytest.fixture
+def one_detector_no_filename_desc() -> str:
+    return """
 COMPONENT nD_Mantid_2 = Monitor_nD(
         options ="mantid square x limits=[0 0.512] bins=1280 y limits=[0 0.512] bins=1280, neutron pixel min=2000000 t, list all neutrons",
     xmin = 0,
@@ -59,7 +74,10 @@
   ROTATED (0, 90, 0) RELATIVE armSample
 """
 
-two_detectors_same_filename = """
+
+@pytest.fixture
+def two_detectors_same_filename_desc() -> str:
+    return """
 COMPONENT nD_Mantid_0 = Monitor_nD(
         options ="mantid square x limits=[0 0.512] bins=1280 y limits=[0 0.512] bins=1280, neutron pixel min=1 t, list all neutrons",
     xmin = 0,
diff --git a/packages/essnmx/tests/mcstas/loader_test.py b/packages/essnmx/tests/mcstas/loader_test.py
index c9d090d3..803c09eb 100644
--- a/packages/essnmx/tests/mcstas/loader_test.py
+++ b/packages/essnmx/tests/mcstas/loader_test.py
@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright (c) 2024 Scipp contributors (https://github.com/scipp)
 import pathlib
-import sys
 from collections.abc import Generator
 
 import pytest
@@ -19,14 +18,6 @@
     NMXRawEventCountsDataGroup,
 )
 
-sys.path.insert(0, str(pathlib.Path(__file__).resolve().parent))
-from mcstas_description_examples import (
-    no_detectors,
-    one_detector_no_filename,
-    two_detectors_same_filename,
-    two_detectors_two_filenames,
-)
-
 
 def check_nmxdata_properties(
     dg: NMXRawEventCountsDataGroup, fast_axis, slow_axis
@@ -133,25 +124,25 @@ def test_missing_rotation(rotation_mission_tmp_file: FilePath) -> None:
         # McStasInstrument is not used due to error in the file.
 
 
-def test_bank_names_to_detector_names_two_detectors():
-    res = bank_names_to_detector_names(two_detectors_two_filenames)
+def test_bank_names_to_detector_names_two_detectors(two_detectors_two_filenames_desc):
+    res = bank_names_to_detector_names(two_detectors_two_filenames_desc)
     assert len(res) == 2
     assert all(len(v) == 1 for v in res.values())
 
 
-def test_bank_names_to_detector_names_same_filename():
-    res = bank_names_to_detector_names(two_detectors_same_filename)
+def test_bank_names_to_detector_names_same_filename(two_detectors_same_filename_desc):
+    res = bank_names_to_detector_names(two_detectors_same_filename_desc)
     assert len(res) == 1
     assert all(len(v) == 2 for v in res.values())
 
 
-def test_bank_names_to_detector_names_no_detectors():
-    res = bank_names_to_detector_names(no_detectors)
+def test_bank_names_to_detector_names_no_detectors(no_detectors_desc):
+    res = bank_names_to_detector_names(no_detectors_desc)
     assert len(res) == 0
 
 
-def test_bank_names_to_detector_names_no_filename():
-    res = bank_names_to_detector_names(one_detector_no_filename)
+def test_bank_names_to_detector_names_no_filename(one_detector_no_filename_desc):
+    res = bank_names_to_detector_names(one_detector_no_filename_desc)
     assert len(res) == 1
     ((bank, (detector,)),) = res.items()
     assert bank == detector