Extract the storage layer into core/ (bundled in the integration)

Extract the storage layer into core/ (bundled in the integration)

tests/test_core_isolation.py

@@ -0,0 +1,119 @@
+"""Invariant: the bundled core package is self-contained.
+
+Every module under ``custom_components/nestquest/core/`` must be free of
+Home Assistant and must not climb out of the core package: no
+``homeassistant`` import, no relative import with level > 1, no absolute
+import of ``custom_components.nestquest.<something other than core>``,
+and no bare ``import core`` / ``from core``.  This guards the
+storage-layer extraction (task d0b691d8) from regressing into a
+HA-coupled or integration-coupled bundle.
+"""
+from __future__ import annotations
+
+import ast
+from pathlib import Path
+
+CORE_PKG = Path(
+    __import__(
+        "custom_components.nestquest.core", fromlist=["__file__"]
+    ).__file__
+).parent
+
+
+def _module_chain(base: str, name: str) -> str:
+    """Combined dotted path for ``from <base> import <name>``."""
+    return f"{base}.{name}" if base else name
+
+
+def _is_homeassistant(module: str) -> bool:
+    return module == "homeassistant" or module.startswith("homeassistant.")
+
+
+def _climbs_out_of_core(module: str) -> bool:
+    """An absolute path that reaches the integration package but not core."""
+    if module == "custom_components.nestquest":
+        return True
+    if module.startswith("custom_components.nestquest."):
+        rest = module[len("custom_components.nestquest."):]
+        head = rest.split(".", 1)[0]
+        return head != "core"
+    return False
+
+
+def _is_bare_core(module: str) -> bool:
+    """A bare ``core`` / ``core.*`` absolute reference (not the bundle)."""
+    return module == "core" or module.startswith("core.")
+
+
+def _scan(path: Path) -> list[str]:
+    tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
+    offenders: list[str] = []
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Import):
+            for alias in node.names:
+                mod = alias.name
+                if _is_homeassistant(mod):
+                    offenders.append(
+                        f"{path.name}:{node.lineno} homeassistant import: import {mod}"
+                    )
+                if _is_bare_core(mod):
+                    offenders.append(
+                        f"{path.name}:{node.lineno} bare core import: import {mod}"
+                    )
+                if _climbs_out_of_core(mod):
+                    offenders.append(
+                        f"{path.name}:{node.lineno} climbs out of core: import {mod}"
+                    )
+        elif isinstance(node, ast.ImportFrom):
+            if node.level and node.level > 1:
+                offenders.append(
+                    f"{path.name}:{node.lineno} relative import climbs out "
+                    f"of core (level {node.level})"
+                )
+                continue
+            if node.level:
+                # relative level 1 stays inside core; nothing to check.
+                continue
+            base = node.module or ""
+            if _is_homeassistant(base):
+                offenders.append(
+                    f"{path.name}:{node.lineno} homeassistant import: from {base}"
+                )
+            if _is_bare_core(base):
+                offenders.append(
+                    f"{path.name}:{node.lineno} bare core import: from {base}"
+                )
+            if _climbs_out_of_core(base):
+                offenders.append(
+                    f"{path.name}:{node.lineno} climbs out of core: from {base}"
+                )
+            for alias in node.names:
+                combined = _module_chain(base, alias.name)
+                if _is_homeassistant(combined):
+                    offenders.append(
+                        f"{path.name}:{node.lineno} homeassistant import: "
+                        f"from {base} import {alias.name}"
+                    )
+                if _is_bare_core(combined):
+                    offenders.append(
+                        f"{path.name}:{node.lineno} bare core import: "
+                        f"from {base} import {alias.name}"
+                    )
+                if _climbs_out_of_core(combined):
+                    offenders.append(
+                        f"{path.name}:{node.lineno} climbs out of core: "
+                        f"from {base} import {alias.name}"
+                    )
+    return offenders
+
+
+def test_core_package_is_self_contained() -> None:
+    """No core module imports homeassistant or climbs out of the core package."""
+    py_files = sorted(CORE_PKG.rglob("*.py"))
+    assert py_files, "core package not found under custom_components/nestquest/core"
+    all_offenders: list[str] = []
+    for py_file in py_files:
+        all_offenders.extend(_scan(py_file))
+    assert all_offenders == [], (
+        "core package isolation violated:\n" + "\n".join(all_offenders)
+    )