fix(regex): Construct backreferences to ensure entity consistency

tools/schemacode/bidsschematools/rules.py

@@ -69,6 +69,16 @@ def _format_entity(entity, name, pattern, level, directory=False):
     if directory and entity not in DIR_ENTITIES:
         return ""
 
+    # For a directory entity appearing in a filename, match the value
+    # found in the directory name
+    # Note that this makes it impossible to do something like
+    # /ses-1_dwi.json instead of /sub-??/ses-1/sub-??_ses-1_dwi.json
+    # We'll assume this is a negligible use case.
+    # It is possible to create such a regular expression, but doing it
+    # in a piecewise fashion is difficult.
+    if not directory and entity in DIR_ENTITIES:
+        return rf"(?({entity}){name}-(?P={entity})_)"
+
     label = _capture_regex(entity, pattern, not directory and entity in DIR_ENTITIES)
     post = "/" if directory else "_"
 

tools/schemacode/bidsschematools/tests/test_rules.py

@@ -1,3 +1,5 @@
+import re
+
 from bidsschematools import rules
 
 from ..types import Namespace
@@ -13,19 +15,29 @@ def test_entity_rule(schema_obj):
             "extensions": [".nii"],
         }
     )
-    assert rules._entity_rule(rule, schema_obj) == {
+    nii_rule = rules._entity_rule(rule, schema_obj)
+    assert nii_rule == {
         "regex": (
             r"sub-(?P<subject>[0-9a-zA-Z]+)/"
             r"(?:ses-(?P<session>[0-9a-zA-Z]+)/)?"
             r"(?P<datatype>anat)/"
-            r"sub-(?P=subject)_"
-            r"(?:ses-(?P=session)_)?"
+            r"(?(subject)sub-(?P=subject)_)"
+            r"(?(session)ses-(?P=session)_)"
             r"(?P<suffix>T1w)"
             r"(?P<extension>\.nii)\Z"
         ),
         "mandatory": False,
     }
 
+    assert re.match(nii_rule["regex"], "sub-01/anat/sub-01_T1w.nii")
+    assert re.match(nii_rule["regex"], "sub-01/ses-01/anat/sub-01_ses-01_T1w.nii")
+    assert not re.match(nii_rule["regex"], "sub-01/anat/sub-02_T1w.nii")
+    assert not re.match(nii_rule["regex"], "sub-01/sub-01_T1w.nii")
+    assert not re.match(nii_rule["regex"], "sub-01_T1w.nii")
+    assert not re.match(nii_rule["regex"], "sub-01/ses-01/anat/sub-01_T1w.nii")
+    assert not re.match(nii_rule["regex"], "sub-01/anat/sub-01_ses-01_T1w.nii")
+    assert not re.match(nii_rule["regex"], "sub-01/ses-01/anat/sub-01_ses-02_T1w.nii")
+
     # Sidecar entities are optional
     rule = Namespace.build(
         {
@@ -35,18 +47,31 @@ def test_entity_rule(schema_obj):
             "extensions": [".json"],
         }
     )
-    assert rules._entity_rule(rule, schema_obj) == {
+    json_rule = rules._entity_rule(rule, schema_obj)
+    assert json_rule == {
         "regex": (
             r"(?:sub-(?P<subject>[0-9a-zA-Z]+)/)?"
             r"(?:ses-(?P<session>[0-9a-zA-Z]+)/)?"
             r"(?:(?P<datatype>anat)/)?"
-            r"(?:sub-(?P=subject)_)?"
-            r"(?:ses-(?P=session)_)?"
+            r"(?(subject)sub-(?P=subject)_)"
+            r"(?(session)ses-(?P=session)_)"
             r"(?P<suffix>T1w)"
             r"(?P<extension>\.json)\Z"
         ),
         "mandatory": False,
     }
+    assert re.match(json_rule["regex"], "sub-01/anat/sub-01_T1w.json")
+    assert re.match(json_rule["regex"], "sub-01/sub-01_T1w.json")
+    assert re.match(json_rule["regex"], "T1w.json")
+    assert re.match(json_rule["regex"], "sub-01/ses-01/anat/sub-01_ses-01_T1w.json")
+    assert re.match(json_rule["regex"], "sub-01/ses-01/sub-01_ses-01_T1w.json")
+    assert not re.match(json_rule["regex"], "sub-01/anat/sub-02_T1w.json")
+    assert not re.match(json_rule["regex"], "sub-01_T1w.json")
+    assert not re.match(json_rule["regex"], "ses-01_T1w.json")
+    assert not re.match(json_rule["regex"], "sub-01/ses-01/anat/sub-01_T1w.json")
+    assert not re.match(json_rule["regex"], "sub-01/anat/sub-01_ses-01_T1w.json")
+    assert not re.match(json_rule["regex"], "sub-01/ses-01/ses-01_T1w.json")
+    assert not re.match(json_rule["regex"], "sub-01/ses-01/anat/sub-01_ses-02_T1w.json")
 
 
 def test_split_inheritance_rules():

tools/schemacode/bidsschematools/tests/test_validator.py

@@ -29,6 +29,42 @@ def test_inheritance_examples():
     assert result["path_tracking"] == incorrect_inheritance
 
 
+def test_regression_examples():
+    """Tests that failed on pybids when switching to bst-regex-based validation"""
+    examples = [
+        "/sub-01/ses-ses/sub-01_dwi.bval",  # redundant dir /ses-ses/
+        "/sub-01/01_dwi.bvec",  # missed subject suffix
+        "/sub-01/sub_dwi.json",  # missed subject id
+        "/sub-01/sub-01_23_run-01_dwi.bval",  # wrong _23_
+        "/sub-01/sub-01_run-01_dwi.vec",  # wrong extension
+        "/sub-01/sub-01_run-01_dwi.jsn",  # wrong extension
+        "/sub-01/sub-01_acq_dwi.bval",  # missed suffix value
+        "/sub-01/sub-01_acq-23-singleband_dwi.bvec",  # redundant -23-
+        "/sub-01/anat/sub-01_acq-singleband_dwi.json",  # redundant /anat/
+        "/sub-01/sub-01_recrod-record_acq-singleband_run-01_dwi.bval",  # redundant record-record_
+        "/sub_01/sub-01_acq-singleband_run-01_dwi.bvec",  # wrong /sub_01/
+        "/sub-01/sub-01_acq-singleband__run-01_dwi.json",  # wrong __
+        "/sub-01/ses-test/sub-01_ses_test_dwi.bval",  # wrong ses_test
+        "/sub-01/ses-test/sb-01_ses-test_dwi.bvec",  # wrong sb-01
+        "/sub-01/ses-test/sub-01_ses-test_dw.json",  # wrong modality
+        "/sub-01/ses-test/sub-01_ses-test_run-01_dwi.val",  # wrong extension
+        "/sub-01/ses-test/sub-01_run-01_dwi.bvec",  # missed session in the filename
+        # This validator adds a .*/ to the regex, so this will be a false negative
+        # If I cared about this validator, I would dig into it, but it doesn't seem worth it.
+        # -cjm 2024.08.14
+        # "/sub-01/ses-test/ses-test_run-01_dwi.json",  # missed subject in the filename
+        "/sub-01/ses-test/sub-01_ses-test_acq-singleband.bval",  # missed modality
+        "/sub-01/ses-test/sub-01_ses-test_acq-singleband_dwi",  # missed extension
+        "/ses-test/sub-01/sub-01_ses-test_acq-singleband_dwi.json",  # wrong dirs order
+        "/sub-01/ses-test/sub-02_ses-test_acq-singleband_run-01_dwi.bval",  # wrong sub id
+        "/sub-01/sub-01_ses-test_acq-singleband_run-01_dwi.bvec",  # ses dir missed
+        "/ses-test/sub-01_ses-test_acq-singleband_run-01_dwi.json",  # sub id dir missed
+    ]
+
+    result = validate_bids(examples, dummy_paths=True)
+    assert result["path_tracking"] == examples
+
+
 def test_write_report(tmp_path):
     from bidsschematools.validator import write_report