[lvgl] Memoize obj_schema by widget_type (#16615)

tests/component_tests/lvgl/test_obj_schema_cache.py

@@ -0,0 +1,67 @@
+"""Tests for obj_schema() memoization."""
+
+from __future__ import annotations
+
+from collections.abc import Generator
+
+import pytest
+
+import esphome.components.lvgl  # noqa: F401
+from esphome.components.lvgl import schemas as lvgl_schemas
+from esphome.components.lvgl.schemas import WIDGET_TYPES, obj_schema
+
+
+@pytest.fixture(autouse=True)
+def _clear_obj_schema_cache() -> Generator[None]:
+    cache = getattr(lvgl_schemas, "_OBJ_SCHEMA_CACHE", None)
+    if cache is not None:
+        cache.clear()
+    yield
+    if cache is not None:
+        cache.clear()
+
+
+def _widget_type(name: str = "obj"):
+    wt = WIDGET_TYPES.get(name)
+    assert wt is not None, f"widget type {name!r} not registered"
+    return wt
+
+
+def test_same_widget_type_returns_same_schema() -> None:
+    wt = _widget_type("obj")
+    assert obj_schema(wt) is obj_schema(wt)
+
+
+def test_different_widget_types_return_different_schemas() -> None:
+    assert obj_schema(_widget_type("obj")) is not obj_schema(_widget_type("label"))
+
+
+def test_cache_is_populated_after_first_call() -> None:
+    wt = _widget_type("obj")
+    assert id(wt) not in lvgl_schemas._OBJ_SCHEMA_CACHE
+    obj_schema(wt)
+    assert id(wt) in lvgl_schemas._OBJ_SCHEMA_CACHE
+
+
+def test_cached_schema_produces_equivalent_output() -> None:
+    wt = _widget_type("obj")
+    cached_result = obj_schema(wt)({})
+    lvgl_schemas._OBJ_SCHEMA_CACHE.clear()
+    fresh_result = obj_schema(wt)({})
+    assert cached_result == fresh_result
+
+
+def test_id_recycling_is_caught_by_identity_guard() -> None:
+    wt = _widget_type("obj")
+    real_schema = obj_schema(wt)
+
+    cached_widget_type, _ = lvgl_schemas._OBJ_SCHEMA_CACHE[id(wt)]
+    sentinel_schema = object()
+    lvgl_schemas._OBJ_SCHEMA_CACHE[id(wt)] = (cached_widget_type, sentinel_schema)
+    assert obj_schema(wt) is sentinel_schema
+
+    other = _widget_type("label")
+    lvgl_schemas._OBJ_SCHEMA_CACHE[id(wt)] = (other, sentinel_schema)
+    rebuilt = obj_schema(wt)
+    assert rebuilt is not sentinel_schema
+    assert rebuilt is not real_schema