Pylint plugin to check __init__ return type (#50868)

* Pylint plugin to check __init__ return type

* Support *args add **kwargs, type hints

* Use 'in' instead of 'any()'

* Fix last few places

homeassistant/components/harmony/switch.py

@@ -30,7 +30,7 @@ async def async_setup_entry(hass, entry, async_add_entities):
 class HarmonyActivitySwitch(ConnectionStateMixin, SwitchEntity):
     """Switch representation of a Harmony activity."""
 
-    def __init__(self, name: str, activity: dict, data: HarmonyData):
+    def __init__(self, name: str, activity: dict, data: HarmonyData) -> None:
         """Initialize HarmonyActivitySwitch class."""
         super().__init__()
         self._name = name

homeassistant/components/tesla/config_flow.py

@@ -114,7 +114,7 @@ class TeslaConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
 class OptionsFlowHandler(config_entries.OptionsFlow):
     """Handle a option flow for Tesla."""
 
-    def __init__(self, config_entry: config_entries.ConfigEntry):
+    def __init__(self, config_entry: config_entries.ConfigEntry) -> None:
         """Initialize options flow."""
         self.config_entry = config_entry
 

pylint/plugins/hass_constructor.py

@@ -0,0 +1,52 @@
+"""Plugin for constructor definitions."""
+from astroid import ClassDef, Const, FunctionDef
+from pylint.checkers import BaseChecker
+from pylint.interfaces import IAstroidChecker
+from pylint.lint import PyLinter
+
+
+class HassConstructorFormatChecker(BaseChecker):  # type: ignore[misc]
+    """Checker for __init__ definitions."""
+
+    __implements__ = IAstroidChecker
+
+    name = "hass_constructor"
+    priority = -1
+    msgs = {
+        "W0006": (
+            '__init__ should have explicit return type "None"',
+            "hass-constructor-return",
+            "Used when __init__ has all arguments typed "
+            "but doesn't have return type declared",
+        ),
+    }
+    options = ()
+
+    def visit_functiondef(self, node: FunctionDef) -> None:
+        """Called when a FunctionDef node is visited."""
+        if not node.is_method() or node.name != "__init__":
+            return
+
+        # Check that all arguments are annotated.
+        # The first argument is "self".
+        args = node.args
+        annotations = (
+            args.posonlyargs_annotations
+            + args.annotations
+            + args.kwonlyargs_annotations
+        )[1:]
+        if args.vararg is not None:
+            annotations.append(args.varargannotation)
+        if args.kwarg is not None:
+            annotations.append(args.kwargannotation)
+        if not annotations or None in annotations:
+            return
+
+        # Check that return type is specified and it is "None".
+        if not isinstance(node.returns, Const) or node.returns.value != None:
+            self.add_message("hass-constructor-return", node=node)
+
+
+def register(linter: PyLinter) -> None:
+    """Register the checker."""
+    linter.register_checker(HassConstructorFormatChecker(linter))

pylint/plugins/hass_logger.py

@@ -1,18 +1,18 @@
+"""Plugin for logger invocations."""
 import astroid
 from pylint.checkers import BaseChecker
 from pylint.interfaces import IAstroidChecker
+from pylint.lint import PyLinter
 
 LOGGER_NAMES = ("LOGGER", "_LOGGER")
 LOG_LEVEL_ALLOWED_LOWER_START = ("debug",)
 
-# This is our checker class.
+
-# Checkers should always inherit from `BaseChecker`.
+class HassLoggerFormatChecker(BaseChecker):  # type: ignore[misc]
-class HassLoggerFormatChecker(BaseChecker):
+    """Checker for logger invocations."""
-    """Add class member attributes to the class locals dictionary."""
 
     __implements__ = IAstroidChecker
 
-    # The name defines a custom section of the config for this checker.
     name = "hass_logger"
     priority = -1
     msgs = {
@@ -27,24 +27,10 @@ class HassLoggerFormatChecker(BaseChecker):
             "All logger messages must start with a capital letter",
         ),
     }
-    options = (
+    options = ()
-        (
-            "hass-logger",
-            {
-                "default": "properties",
-                "help": (
-                    "Validate _LOGGER or LOGGER messages conform to Home Assistant standards."
-                ),
-            },
-        ),
-    )
 
-    def visit_call(self, node):
+    def visit_call(self, node: astroid.Call) -> None:
-        """Called when a :class:`.astroid.node_classes.Call` node is visited.
+        """Called when a Call node is visited."""
-        See :mod:`astroid` for the description of available nodes.
-        :param node: The node to check.
-        :type node: astroid.node_classes.Call
-        """
         if not isinstance(node.func, astroid.Attribute) or not isinstance(
             node.func.expr, astroid.Name
         ):
@@ -67,19 +53,16 @@ class HassLoggerFormatChecker(BaseChecker):
             return
 
         if log_message[-1] == ".":
-            self.add_message("hass-logger-period", args=node.args, node=node)
+            self.add_message("hass-logger-period", node=node)
 
         if (
             isinstance(node.func.attrname, str)
             and node.func.attrname not in LOG_LEVEL_ALLOWED_LOWER_START
             and log_message[0].upper() != log_message[0]
         ):
-            self.add_message("hass-logger-capital", args=node.args, node=node)
+            self.add_message("hass-logger-capital", node=node)
 
 
-def register(linter):
+def register(linter: PyLinter) -> None:
-    """This required method auto registers the checker.
+    """Register the checker."""
-    :param linter: The linter to register the checker to.
-    :type linter: pylint.lint.PyLinter
-    """
     linter.register_checker(HassLoggerFormatChecker(linter))

pyproject.toml

@@ -27,7 +27,8 @@ init-hook='from pylint.config.find_default_config_files import find_default_conf
 load-plugins = [
     "pylint.extensions.typing",
     "pylint_strict_informational",
-    "hass_logger"
+    "hass_constructor",
+    "hass_logger",
 ]
 persistent = false
 extension-pkg-whitelist = [