fix(bids): apply CodeRabbit feedback

- Update setup.py to include nibabel in BIDS extra
- Update docs to clarify nibabel is included
- Add nibabel availability check in _info()
- Move os import to module level
- Update test skipif to check both pybids and nibabel

Author: The-Obstacle-Is-The-Way

docs/source/bids_dataset.mdx

@@ -4,7 +4,7 @@
 
 <Tip>
 
-To use the BIDS loader, you need to install the `bids` extra:
+To use the BIDS loader, you need to install the `bids` extra (which installs `pybids` and `nibabel`):
 
 ```bash
 pip install datasets[bids]

setup.py

@@ -210,7 +210,7 @@
 
 NIBABEL_REQUIRE = ["nibabel>=5.3.2", "ipyniivue==2.4.2"]
 
-PYBIDS_REQUIRE = ["pybids>=0.21.0"]
+PYBIDS_REQUIRE = ["pybids>=0.21.0"] + NIBABEL_REQUIRE
 
 EXTRAS_REQUIRE = {
     "audio": AUDIO_REQUIRE,

src/datasets/packaged_modules/bids/bids.py

@@ -1,4 +1,5 @@
 import json
+import os
 from dataclasses import dataclass
 from typing import Optional
 
@@ -28,6 +29,8 @@ class Bids(datasets.GeneratorBasedBuilder):
     def _info(self):
         if not config.PYBIDS_AVAILABLE:
             raise ImportError("To load BIDS datasets, please install pybids: pip install pybids")
+        if not config.NIBABEL_AVAILABLE:
+            raise ImportError("To load BIDS datasets, please install nibabel: pip install nibabel")
 
         return datasets.DatasetInfo(
             features=datasets.Features(
@@ -46,8 +49,6 @@ def _info(self):
         )
 
     def _split_generators(self, dl_manager):
-        import os
-
         from bids import BIDSLayout
 
         if not self.config.data_dir:

tests/packaged_modules/test_bids.py

@@ -75,7 +75,6 @@ def test_bids_module_imports():
 
 def test_bids_requires_pybids(monkeypatch):
     """Test helpful error when pybids not installed."""
-    import datasets.config
     from datasets.packaged_modules.bids.bids import Bids
 
     monkeypatch.setattr(datasets.config, "PYBIDS_AVAILABLE", False)
@@ -84,7 +83,10 @@ def test_bids_requires_pybids(monkeypatch):
         Bids()
 
 
-@pytest.mark.skipif(not datasets.config.PYBIDS_AVAILABLE, reason="pybids not installed")
+@pytest.mark.skipif(
+    not datasets.config.PYBIDS_AVAILABLE or not datasets.config.NIBABEL_AVAILABLE,
+    reason="pybids or nibabel not installed",
+)
 def test_bids_loads_single_subject(minimal_bids_dataset):
     from datasets import load_dataset
 
@@ -100,7 +102,10 @@ def test_bids_loads_single_subject(minimal_bids_dataset):
     assert sample["session"] is None
 
 
-@pytest.mark.skipif(not datasets.config.PYBIDS_AVAILABLE, reason="pybids not installed")
+@pytest.mark.skipif(
+    not datasets.config.PYBIDS_AVAILABLE or not datasets.config.NIBABEL_AVAILABLE,
+    reason="pybids or nibabel not installed",
+)
 def test_bids_multi_subject(multi_subject_bids):
     from datasets import load_dataset