refactor: extract ocf/ — fold sensors.index_links into StateCache.index_device_tree

tests/test_state_cache.py

@@ -0,0 +1,40 @@
+# tests/test_state_cache.py
+from ocf.state_cache import StateCache
+
+
+class _FakeDescriptor:
+    on_observation = None
+
+
+def test_index_device_tree_skips_device_level_entry_at_index_zero():
+    tree = [
+        {'href': '/device/0', 'rep': {'n': 'Dryer'}},   # device-level, skipped
+        {'href': '/mode/vs/0', 'rep': {'x': 1}},
+        {'href': '/power/vs/0', 'rep': {'y': 2}},
+    ]
+    indexed = StateCache.index_device_tree(tree)
+    assert indexed == {'/mode/vs/0': {'x': 1}, '/power/vs/0': {'y': 2}}
+    assert '/device/0' not in indexed
+
+
+def test_index_device_tree_stub_entry_becomes_empty_dict():
+    tree = [
+        {'href': '/device/0', 'rep': {}},
+        {'href': '/oven/vs/0'},   # no 'rep' key at all — a stub resource
+    ]
+    indexed = StateCache.index_device_tree(tree)
+    assert indexed == {'/oven/vs/0': {}}
+
+
+def test_index_device_tree_non_list_input_returns_empty():
+    assert StateCache.index_device_tree({'not': 'a list'}) == {}
+    assert StateCache.index_device_tree(None) == {}
+
+
+def test_apply_rep_reports_change_and_updates_cache():
+    cache = StateCache(_FakeDescriptor())
+    changed = cache.apply_rep('/mode/vs/0', {'x': 1}, source='poll')
+    assert changed is True
+    assert cache.get('/mode/vs/0') == {'x': 1}
+    unchanged = cache.apply_rep('/mode/vs/0', {'x': 1}, source='poll')
+    assert unchanged is False