diff --git a/tests/test_graph_unit.py b/tests/test_graph_unit.py
new file mode 100644
index 0000000..2e3b14c
--- /dev/null
+++ b/tests/test_graph_unit.py
@@ -0,0 +1,20 @@
+from fastapi.testclient import TestClient
+from app.main import create_app
+import app.core.graph_adapter as ga
+
+def _fake_get_edges_for_sources(client, prefix, source_ids, edge_types=None, limit=2048):
+    note_id = source_ids[0]
+    return [
+        {"source_id":note_id,"target_id":f"{note_id}#c1","kind":"references","weight":0.2},
+        {"source_id":note_id,"target_id":f"{note_id}#c2","kind":"belongs_to","weight":0.1},
+    ]
+
+def test_graph_neighbors(monkeypatch):
+    monkeypatch.setattr(ga, "get_edges_for_sources", _fake_get_edges_for_sources, raising=False)
+    app = create_app()
+    with TestClient(app) as c:
+        r = c.get("/graph/TEST-NOTE?depth=1")
+        assert r.status_code == 200
+        g = r.json()
+        assert g["center_note_id"] == "TEST-NOTE"
+        assert g["stats"]["edge_count"] == 2