MRG: Fix bug with writing ctc/cal for emptyroom (#1189)

doc/whats_new.rst

@@ -46,6 +46,7 @@ Detailed list of changes
 ^^^^^^^^^^^^
 
 - Fix reading when the channel order differs between ``*_channels.tsv`` and the raw data file, which would previously throw an error, by `Richard Höchenberger`_ (:gh:`1171`)
+- Fix bug with writing crosstalk and calibration files when subject is ``"emptyroom"``, by `Eric Larson`_ (:gh:`1189`)
 - Make ``recording`` entity available for :func:`mne_bids.get_entity_vals`, by `Stefan Appelhoff`_ (:gh:`1182`)
 
 :doc:`Find out what was new in previous releases <whats_new_previous_releases>`

mne_bids/path.py

@@ -1073,8 +1073,16 @@ def _check(self):
 
         # perform deeper check if user has it turned on
         if self.check:
-            if self.subject == "emptyroom":
-                _check_empty_room_basename(self)
+            _check_empty_room_basename(self)
+
+            if (
+                self.acquisition in ("calibration", "crosstalk")
+                and self.task is not None
+            ):
+                raise ValueError(
+                    f'task must be None if the acquisition is "calibration" or '
+                    f'"crosstalk", but received: {self.task}'
+                )
 
             # ensure extension starts with a '.'
             extension = self.extension

mne_bids/tests/test_write.py

@@ -2660,6 +2660,10 @@ def test_write_meg_calibration(_bids_validate, tmp_path):
     write_meg_calibration(calibration=calibration, bids_path=bids_path)
     _bids_validate(bids_root)
 
+    # subject emptyroom
+    bids_path_erm = bids_path.copy().update(subject="emptyroom", task="noise")
+    write_meg_calibration(calibration=fine_cal_fname, bids_path=bids_path_erm)
+
     # Test passing in incompatible dict.
     calibration = mne.preprocessing.read_fine_calibration(fine_cal_fname)
     del calibration["locs"]
@@ -2686,7 +2690,7 @@ def test_write_meg_calibration(_bids_validate, tmp_path):
 def test_write_meg_crosstalk(_bids_validate, tmp_path):
     """Test writing of the Elekta/Neuromag fine-calibration file."""
     bids_root = tmp_path / "bids1"
-    bids_path = _bids_path.copy().update(root=bids_root)
+    bids_path = _bids_path.copy().update(root=bids_root, suffix="meg")
 
     raw_fname = op.join(data_path, "MEG", "sample", "sample_audvis_trunc_raw.fif")
     raw = _read_raw_fif(raw_fname, verbose=False)
@@ -2697,6 +2701,13 @@ def test_write_meg_crosstalk(_bids_validate, tmp_path):
     write_meg_crosstalk(fname=crosstalk_fname, bids_path=bids_path)
     _bids_validate(bids_root)
 
+    # subject emptyroom
+    bids_path_erm = bids_path.copy().update(subject="emptyroom", task="noise")
+    write_meg_crosstalk(fname=crosstalk_fname, bids_path=bids_path_erm)
+
+    # bad path when task is provided for crosstalk
+    with pytest.raises(ValueError, match="task must be None if the acquisition is"):
+        assert bids_path_erm.copy().update(acquisition="crosstalk").task == "noise"
     # subject not set.
     bids_path = bids_path.copy().update(root=bids_root, subject=None)
     with pytest.raises(ValueError, match="must have root and subject set"):

mne_bids/utils.py

@@ -329,20 +329,19 @@ def _scale_coord_to_meters(coord, unit):
         return coord
 
 
-def _check_empty_room_basename(bids_path, on_invalid_er_task="raise"):
+def _check_empty_room_basename(bids_path):
+    if bids_path.subject != "emptyroom":
+        return
     # only check task entity for emptyroom when it is the sidecar/MEG file
-    if bids_path.suffix == "meg":
-        if bids_path.task != "noise":
-            msg = (
-                f'task must be "noise" if subject is "emptyroom", but '
-                f"received: {bids_path.task}"
-            )
-            if on_invalid_er_task == "raise":
-                raise ValueError(msg)
-            elif on_invalid_er_task == "warn":
-                logger.critical(msg)
-            else:
-                pass
+    if bids_path.suffix != "meg":
+        return
+    if bids_path.acquisition in ("calibration", "crosstalk"):
+        return
+    if bids_path.task != "noise":
+        raise ValueError(
+            f'task must be "noise" if subject is "emptyroom", but '
+            f"received: {bids_path.task}"
+        )
 
 
 def _check_anonymize(anonymize, raw, ext):