diff --git a/common/statedata.py b/common/statedata.py
index 2c0c9a8ca..4f4cfff6a 100644
--- a/common/statedata.py
+++ b/common/statedata.py
@@ -158,7 +158,8 @@ def _set_save_meta_data(self):
         self['_meta'] = meta
 
     def save(self):
-        """Store application state data to a file."""
+        """Store application state data to a file.
+        """
         logger.debug('Save state data.')
 
         self._set_save_meta_data()
diff --git a/common/test/test_statedata.py b/common/test/test_statedata.py
index a78f8dc60..dee3887fd 100644
--- a/common/test/test_statedata.py
+++ b/common/test/test_statedata.py
@@ -5,12 +5,17 @@
 # This file is part of the program "Back In Time" which is released under GNU
 # General Public License v2 (GPLv2). See LICENSES directory or go to
 # <https://spdx.org/licenses/GPL-2.0-or-later.html>.
-"""Tests about statefile module."""
+"""Tests about statefile module.
+
+Dev note (buhtz, 2025-01):
+Consider that the state file is written to disc, via StateData.save() method,
+when the application exists. This is triggered using the atexit module. But
+at the point of application exit PyFakeFS do not work anymore. So state data
+from unit tests is written to the real disc.
+"""
 # pylint: disable=R0801
 import unittest
 import inspect
-import atexit
-import argparse
 from pathlib import Path
 import pyfakefs.fake_filesystem_unittest as pyfakefs_ut
 import statedata
@@ -55,113 +60,6 @@ def test_content(self):
         self.assertEqual(one, two)
 
 
-class Migration(pyfakefs_ut.TestCase):
-    """Migration from config file into state file."""
-    @classmethod
-    def tearDownClass(cls):
-        # Delete existing StateData instance
-        try:
-            # pylint: disable-next=protected-access
-            del statedata.StateData._instances[statedata.StateData]
-        except KeyError:
-            pass
-
-    def _create_config_file(self, extra_content=None):
-        """Minimal config file"""
-        # pylint: disable-next=duplicate-code
-        cfg_content = inspect.cleandoc('''
-            config.version=6
-            profile1.snapshots.no_on_battery=false
-            profile1.snapshots.notify.enabled=true
-            profile1.snapshots.path=rootpath/destination
-            profile1.snapshots.path.host=test-host
-            profile1.snapshots.path.profile=1
-            profile1.snapshots.path.user=test-user
-            profile1.snapshots.remove_old_snapshots.enabled=true
-            profile1.snapshots.remove_old_snapshots.unit=80
-            profile1.snapshots.remove_old_snapshots.value=10
-            profile1.snapshots.include.1.type=0
-            profile1.snapshots.include.1.value=rootpath/source
-            profile1.snapshots.include.size=1
-            profile1.snapshots.preserve_acl=false
-            profile1.snapshots.preserve_xattr=false
-            profile1.snapshots.rsync_options.enabled=false
-            profile1.snapshots.rsync_options.value=
-            profiles.version=1
-            qt.main_window.x=123
-            qt.main_window.y=456
-        ''')  # pylint: disable=R0801
-
-        if extra_content:
-            cfg_content = cfg_content + '\n' + '\n'.join(extra_content)
-
-        # config file location
-        config_fp = Path.home() / '.config' / 'backintime' / 'config'
-        config_fp.parent.mkdir(parents=True)
-        config_fp.write_text(cfg_content, 'utf-8')
-
-        return config_fp
-
-    def tearDown(self):
-        self.config_fp.unlink(missing_ok=True)
-        self.state_fp.unlink(missing_ok=True)
-
-    def setUp(self):
-        """Setup a fake filesystem with a config file."""
-        self.setUpPyfakefs(allow_root_user=False)
-
-        # Delete existing StateData instance
-        try:
-            # pylint: disable-next=protected-access
-            del statedata.StateData._instances[statedata.StateData]
-        except KeyError:
-            pass
-
-        self.config_fp = self._create_config_file()
-        self.state_fp = Path.home() / '.local' / 'state' / 'backintime.json'
-
-    def test_create_json_file_at_exit(self):
-        """Create state file if not exists."""
-
-        # State file does not exist
-        self.assertFalse(self.state_fp.exists())
-
-        # Try to load statefile will trigger migration of config values
-        # into a fresh state object
-        args = argparse.Namespace(
-            config="/home/user/.config/backintime/config",
-            share_path="/home/user/.local/share")
-        backintime.load_state_data(args)
-
-        statedata.StateData()
-
-        # File still not written to filesystem
-        self.assertFalse(self.state_fp.exists())
-
-        # Exit application trigger state file write
-        atexit._run_exitfuncs()  # pylint: disable=protected-access
-
-        # Not it exists
-        self.assertTrue(self.state_fp.exists())
-
-    def test_migrate_config(self):
-        """Values from config file migrated to state data."""
-
-        # State file does not exist
-        self.assertFalse(self.state_fp.exists())
-
-        # Try to load statefile will trigger migration of config values
-        # into a fresh state object
-        args = argparse.Namespace(
-            config=str(Path.home() / ".config" / "backintime" / "config"),
-            share_path=str(Path.home() / ".local" / "share"))
-        backintime.load_state_data(args)
-
-        sut = statedata.StateData()
-
-        self.assertEqual(sut.mainwindow_coords, (123, 456))
-
-
 class Properties(unittest.TestCase):
     """Property access without errors."""