test(ariadne): cover storage snapshot edges

tests/test_storage.py

@@ -359,8 +359,27 @@ def test_prune_cluster_state_skips_zero() -> None:
     assert not db.executed
 
 
+def test_prune_cluster_state_executes_with_positive_keep() -> None:
+    db = DummyDB()
+    storage = Storage(db)
+
+    storage.prune_cluster_state(3)
+
+    assert db.executed[-1][1] == (3,)
+
+
 def test_latest_cluster_state_parses_json() -> None:
     db = DummyDB(row={"snapshot": "{\"ok\": true}", "created_at": datetime.now()})
     storage = Storage(db)
     snapshot = storage.latest_cluster_state()
     assert snapshot == {"ok": True}
+
+
+def test_latest_cluster_state_handles_empty_and_native_snapshots() -> None:
+    assert Storage(DummyDB(row=None)).latest_cluster_state() is None
+    assert Storage(DummyDB(row={"snapshot": {"ok": True}, "created_at": datetime.now()})).latest_cluster_state() == {"ok": True}
+
+
+def test_latest_cluster_state_rejects_bad_snapshot_payloads() -> None:
+    assert Storage(DummyDB(row={"snapshot": "{bad", "created_at": datetime.now()})).latest_cluster_state() is None
+    assert Storage(DummyDB(row={"snapshot": 42, "created_at": datetime.now()})).latest_cluster_state() is None