Add admin-only versus open service policy registry

One mapping in service_policy.py: complete_quest is open, every other
registered nestquest service is admin_only.

tests/test_service_policy.py

@@ -0,0 +1,32 @@
+"""Tests for the Feature 09 admin-only versus open service registry."""
+from __future__ import annotations
+
+from custom_components.nestquest.const import (
+    DOMAIN_SERVICES,
+    SERVICE_COMPLETE_QUEST,
+)
+from custom_components.nestquest.service_policy import (
+    ADMIN_ONLY,
+    OPEN,
+    SERVICE_POLICY,
+)
+
+
+def test_policy_covers_exactly_the_registered_services() -> None:
+    assert frozenset(SERVICE_POLICY) == frozenset(DOMAIN_SERVICES)
+
+
+def test_only_complete_quest_is_open() -> None:
+    open_services = {
+        name for name, access in SERVICE_POLICY.items() if access == OPEN
+    }
+    assert open_services == {SERVICE_COMPLETE_QUEST}
+    assert all(
+        access == ADMIN_ONLY
+        for name, access in SERVICE_POLICY.items()
+        if name != SERVICE_COMPLETE_QUEST
+    )
+
+
+def test_policy_values_are_only_open_or_admin_only() -> None:
+    assert set(SERVICE_POLICY.values()) <= {OPEN, ADMIN_ONLY}