Fix BIDSPath partially matching a value

doc/whats_new.rst

@@ -26,6 +26,7 @@ The following authors had contributed before. Thank you for sticking around! 
 * `Stefan Appelhoff`_
 * `Daniel McCloy`_
 * `Scott Huberty`_
+* `Pierre Guetschel`_
 
 Detailed list of changes
 ~~~~~~~~~~~~~~~~~~~~~~~~
@@ -57,6 +58,7 @@ Detailed list of changes
 - BIDS dictates that the recording entity should be displayed as "_recording-" in the filename. This PR makes :class:`mne_bids.BIDSPath`  correctly display "_recording-" (instead of "_rec-") in BIDSPath.fpath. By `Scott Huberty`_ (:gh:`1348`)
 - :func:`mne_bids.make_dataset_description` now correctly encodes the dataset description as UTF-8 on disk, by `Scott Huberty`_ (:gh:`1357`)
 - Corrects extension when filtering filenames in :meth:`mne_bids.BIDSPath.match()` and :func:`mne_bids.find_matching_paths()`, by `Arne Gottwald` (:gh:`1355`)
+- Fix :class:`mne_bids.BIDSPath` partially matching a value, by `Pierre Guetschel` (:gh:`1388`)
 
 ⚕️ Code health
 ^^^^^^^^^^^^^^

mne_bids/path.py

@@ -1390,7 +1390,9 @@ def _get_matching_bidspaths_from_filesystem(bids_path):
             search_str = op.join(search_str, datatype)
         else:
             search_str = op.join(search_str, "**")
-        search_str = op.join(search_str, f"{basename}*")
+        # The basename should end with a separator "_" or a period "."
+        # to avoid matching only the beggining of a value.
+        search_str = op.join(search_str, f"{basename}[_.]*")
 
         # Find all matching files in all supported formats.
         valid_exts = ALLOWED_FILENAME_EXTENSIONS

mne_bids/tests/test_path.py

@@ -1648,3 +1648,26 @@ def test_dont_create_dirs_on_fpath_access(tmp_path):
     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()
+
+
+def test_fpath_common_prefix(tmp_path):
+    """Tests that fpath does not match multiple files with the same prefix.
+
+    This might happen if indices are not zero-paddded.
+    """
+    sub_dir = tmp_path / "sub-1" / "eeg"
+    sub_dir.mkdir(exist_ok=True, parents=True)
+    (sub_dir / "sub-1_run-1_raw.fif").touch()
+    (sub_dir / "sub-1_run-2.edf").touch()
+    # Other valid BIDS paths with the same basename prefix:
+    (sub_dir / "sub-1_run-10_raw.fif").touch()
+    (sub_dir / "sub-1_run-20.edf").touch()
+
+    assert (
+        BIDSPath(root=tmp_path, subject="1", run="1").fpath
+        == sub_dir / "sub-1_run-1_raw.fif"
+    )
+    assert (
+        BIDSPath(root=tmp_path, subject="1", run="2").fpath
+        == sub_dir / "sub-1_run-2.edf"
+    )