Corrected datahandling test case

pystencils_tests/test_datahandling.py

 import os
 from tempfile import TemporaryDirectory
+from pathlib import Path
 
 import numpy as np
 
@@ -12,6 +13,9 @@ except ImportError:
     import unittest.mock
     pytest = unittest.mock.MagicMock()
 
+SCRIPT_FOLDER = Path(__file__).parent
+INPUT_FOLDER = SCRIPT_FOLDER / "test_data"
+
 
 def basic_iteration(dh):
     dh.add_array('basic_iter_test_gl_default')
@@ -321,7 +325,7 @@ def test_save_data():
     dh.add_array("dst", values_per_cell=9)
     dh.fill("dst", 1.0, ghost_layers=True)
 
-    dh.save_all('test_data/datahandling_save_test')
+    dh.save_all(INPUT_FOLDER.name + '/datahandling_save_test')
 
 
 def test_load_data():
@@ -333,7 +337,7 @@ def test_load_data():
     dh.add_array("dst", values_per_cell=9)
     dh.fill("dst", 0.0, ghost_layers=True)
 
-    dh.load_all('test_data/datahandling_load_test')
+    dh.load_all(INPUT_FOLDER.name + '/datahandling_load_test')
     assert np.all(dh.cpu_arrays['src']) == 1
     assert np.all(dh.cpu_arrays['dst']) == 1
 
@@ -347,7 +351,7 @@ def test_load_data():
     dh.add_array("dst2", values_per_cell=9)
     dh.fill("dst2", 0.0, ghost_layers=True)
 
-    dh.load_all('test_data/datahandling_load_test')
+    dh.load_all(INPUT_FOLDER.name + '/datahandling_load_test')
     assert np.all(dh.cpu_arrays['src']) == 0
     assert np.all(dh.cpu_arrays['dst']) == 0
     assert np.all(dh.cpu_arrays['dst2']) == 0