remove abs path

tests/test_io.py

@@ -9,6 +9,7 @@ Modified-History:
     2023-12-15, Bo Zhang, add TestFitsHeaderOps.test_reformat_header
 """
 
+import os
 import unittest
 
 from astropy.io import fits
@@ -144,5 +145,10 @@ class TestFitsHeaderOps(unittest.TestCase):
         self.assertEqual(meta["obs_id"], "123456")
 
     def test_fits_open(self):
-        hl = fits_open("/nfsdata/share/pipeline-unittest/csst_common/test_fits/hl.fits")
+        hl = fits_open(
+            os.path.join(
+                os.environ["UNIT_TEST_DATA_ROOT"],
+                "csst_common/test_fits/hl.fits",
+            )
+        )
         self.assertTrue(isinstance(hl, fits.HDUList))