Merge branch 'main' into min-mne-1.3

doc/whats_new.rst

@@ -57,6 +57,7 @@ Detailed list of changes
 - Fix ``raw_to_bids`` CLI tool to properly recognize boolean and numeric values for the ``line_freq`` and ``overwrite`` parameters, by `Stefan Appelhoff`_ (:gh:`1125`)
 - Fix :func:`~mne_bids.copyfiles.copyfile_eeglab` to prevent data type conversion leading to an ``eeg_checkset`` failure when trying to load the file in EEGLAB, by `Laetitia Fesselier`_ (:gh:`1122`)
 - Improve compatibility with latest MNE-Python, by `Eric Larson`_ (:gh:`1128`)
+- Working with :class:`~mne_bids.BIDSPath` would sometimes inadvertently create new directories, contaminating the BIDS dataset, by `Richard Höchenberger`_ (:gh:`1139`)
 
 :doc:`Find out what was new in previous releases <whats_new_previous_releases>`
 

mne_bids/path.py

@@ -1059,8 +1059,9 @@ def _get_matching_bidspaths_from_filesystem(bids_path):
         datatype = _infer_datatype(root=bids_root,
                                    sub=sub, ses=ses)
 
-    data_dir = BIDSPath(subject=sub, session=ses, datatype=datatype,
-                        root=bids_root).mkdir().directory
+    data_dir = BIDSPath(
+        subject=sub, session=ses, datatype=datatype, root=bids_root
+    ).directory
 
     # For BTI data, just return the directory with a '.pdf' extension
     # to facilitate reading in mne-bids

mne_bids/tests/test_path.py

@@ -1,5 +1,6 @@
 """Test for the MNE BIDSPath functions."""
 # Authors: Adam Li <[email protected]>
+#          Richard Höchenberger <[email protected]>
 #
 # License: BSD-3-Clause
 import os
@@ -1258,3 +1259,10 @@ def test_deprecation():
     """Test deprecated behavior."""
     with pytest.warns(FutureWarning, match='This will raise an exception'):
         BIDSPath(extension='vhdr')  # no leading period
+
+
+def test_dont_create_dirs_on_fpath_access(tmp_path):
+    """Regression test: don't create directories when accessing .fpath."""
+    bp = BIDSPath(subject='01', datatype='eeg', root=tmp_path)
+    bp.fpath  # accessing .fpath is required for this regression test
+    assert not (tmp_path / 'sub-01').exists()