[lvgl] Memoize and lazily build container_schema (#16567)

tests/component_tests/lvgl/test_container_schema_cache.py

@@ -0,0 +1,87 @@
+"""Tests for container_schema() memoization and lazy build."""
+
+from __future__ import annotations
+
+from collections.abc import Generator
+from unittest.mock import patch
+
+import pytest
+
+from esphome import config_validation as cv
+import esphome.components.lvgl  # noqa: F401
+from esphome.components.lvgl import schemas as lvgl_schemas
+from esphome.components.lvgl.schemas import WIDGET_TYPES, container_schema
+
+
+@pytest.fixture(autouse=True)
+def _clear_container_schema_cache() -> Generator[None]:
+    cache = getattr(lvgl_schemas, "_CONTAINER_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_args_return_same_validator() -> None:
+    wt = _widget_type("obj")
+    assert container_schema(wt) is container_schema(wt)
+
+
+def test_extras_none_vs_truthy_get_different_validators() -> None:
+    wt = _widget_type("obj")
+    no_extras = container_schema(wt)
+    extras = {cv.Optional("custom_extra"): cv.string}
+    assert no_extras is not container_schema(wt, extras)
+
+
+def test_different_widget_types_get_different_validators() -> None:
+    assert container_schema(_widget_type("obj")) is not container_schema(
+        _widget_type("label")
+    )
+
+
+def test_schema_build_is_deferred_until_first_validation() -> None:
+    wt = _widget_type("obj")
+    with patch.object(
+        lvgl_schemas, "obj_schema", wraps=lvgl_schemas.obj_schema
+    ) as obj_schema_mock:
+        validator = container_schema(wt)
+        assert obj_schema_mock.call_count == 0
+        validator({})
+        assert obj_schema_mock.call_count == 1
+        validator({})
+        assert obj_schema_mock.call_count == 1
+
+
+def test_cached_validator_produces_equivalent_output() -> None:
+    wt = _widget_type("obj")
+    cached = container_schema(wt)
+    cached_result = cached({})
+    lvgl_schemas._CONTAINER_SCHEMA_CACHE.clear()
+    reference = container_schema(wt)
+    assert cached is not reference
+    assert cached_result == reference({})
+
+
+def test_id_recycling_is_caught_by_identity_guard() -> None:
+    wt = _widget_type("obj")
+    real_extras = {cv.Optional("a"): cv.int_}
+    validator_a = container_schema(wt, real_extras)
+
+    cache_key = (id(wt), id(real_extras))
+    cached_entry = lvgl_schemas._CONTAINER_SCHEMA_CACHE[cache_key]
+    sentinel = {cv.Optional("a"): cv.int_}
+    lvgl_schemas._CONTAINER_SCHEMA_CACHE[cache_key] = (
+        cached_entry[0],
+        sentinel,
+        cached_entry[2],
+    )
+
+    assert container_schema(wt, real_extras) is not validator_a