test: add pytest coverage for plugin utilities

tests/test_registry.py

@@ -0,0 +1,24 @@
+from __future__ import annotations
+
+from pathlib import Path
+
+from afs_scawful.registry import build_dataset_registry
+
+
+def test_build_dataset_registry(tmp_path: Path) -> None:
+    datasets_root = tmp_path / "datasets"
+    dataset_dir = datasets_root / "alpha"
+    dataset_dir.mkdir(parents=True)
+
+    (dataset_dir / "train.jsonl").write_text("{}\n", encoding="utf-8")
+    (dataset_dir / "stats.json").write_text("{\"samples\": 1}\n", encoding="utf-8")
+    (dataset_dir / "metadata.json").write_text("{\"source\": \"test\"}\n", encoding="utf-8")
+
+    registry = build_dataset_registry(datasets_root)
+    datasets = registry["datasets"]
+
+    assert len(datasets) == 1
+    entry = datasets[0]
+    assert entry["name"] == "alpha"
+    assert entry["stats"]["samples"] == 1
+    assert entry["metadata"]["source"] == "test"