Add diagnostics rule to quality_scale hassfest validation (#131859)

script/hassfest/quality_scale_validation/diagnostics.py

@@ -0,0 +1,42 @@
+"""Enforce that the integration implements diagnostics.
+
+https://developers.home-assistant.io/docs/core/integration-quality-scale/rules/diagnostics/
+"""
+
+import ast
+
+from script.hassfest.model import Integration
+
+DIAGNOSTICS_FUNCTIONS = {
+    "async_get_config_entry_diagnostics",
+    "async_get_device_diagnostics",
+}
+
+
+def _has_diagnostics_function(module: ast.Module) -> bool:
+    """Test if the module defines at least one of diagnostic functions."""
+    return any(
+        type(item) is ast.AsyncFunctionDef and item.name in DIAGNOSTICS_FUNCTIONS
+        for item in ast.walk(module)
+    )
+
+
+def validate(integration: Integration) -> list[str] | None:
+    """Validate that the integration implements diagnostics."""
+
+    diagnostics_file = integration.path / "diagnostics.py"
+    if not diagnostics_file.exists():
+        return [
+            "Integration does implement diagnostics platform "
+            "(is missing diagnostics.py)",
+        ]
+
+    diagnostics = ast.parse(diagnostics_file.read_text())
+
+    if not _has_diagnostics_function(diagnostics):
+        return [
+            f"Integration is missing one of {DIAGNOSTICS_FUNCTIONS} "
+            f"in {diagnostics_file}"
+        ]
+
+    return None