adds a simple test for remote s3 datasets

Checks the number of files in an example openneuro s3 dataset. Also adds
s3fs as a test dependency.

bids/layout/tests/test_remote_bids.py

@@ -0,0 +1,26 @@
+""" Tests runs layout on bids examples and make sure all files are caught"""
+
+""" TODO
+- add more 'vanilla' datasets
+- missing files in micr?
+"""
+
+import pytest
+
+from bids.layout import BIDSLayout
+
+# Values for the number of files by downloading dataset first
+
+@pytest.mark.parametrize(
+    "dataset, nb_files",
+    [
+        ("s3://openneuro.org/ds000102", 136),
+    ],
+)
+def test_layout_on_s3_datasets_no_derivatives(dataset, nb_files):
+    layout = BIDSLayout(dataset)
+    files = layout.get()
+    assert len(files) == nb_files
+
+
+

pyproject.toml

@@ -52,6 +52,7 @@ test = [
   "coverage[toml]",
   "altair",
   "pytest-xdist",
+  "s3fs" #for testing remote uri
 ]
 model_reports = [
   "jinja2",