Pylint plugin to check that relative imports are used (#50937)

* Pylint plugin to check that relative imports are used

* Fix existing sites

* Update description message

* Fix typo

pylint/plugins/hass_constructor.py

@@ -1,5 +1,5 @@
 """Plugin for constructor definitions."""
-from astroid import ClassDef, Const, FunctionDef
+from astroid import Const, FunctionDef
 from pylint.checkers import BaseChecker
 from pylint.interfaces import IAstroidChecker
 from pylint.lint import PyLinter
@@ -43,7 +43,7 @@ class HassConstructorFormatChecker(BaseChecker):  # type: ignore[misc]
             return
 
         # Check that return type is specified and it is "None".
-        if not isinstance(node.returns, Const) or node.returns.value != None:
+        if not isinstance(node.returns, Const) or node.returns.value is not None:
             self.add_message("hass-constructor-return", node=node)
 
 

pylint/plugins/hass_imports.py

@@ -0,0 +1,52 @@
+"""Plugin for checking imports."""
+from __future__ import annotations
+
+from astroid import Import, ImportFrom, Module
+from pylint.checkers import BaseChecker
+from pylint.interfaces import IAstroidChecker
+from pylint.lint import PyLinter
+
+
+class HassImportsFormatChecker(BaseChecker):  # type: ignore[misc]
+    """Checker for imports."""
+
+    __implements__ = IAstroidChecker
+
+    name = "hass_imports"
+    priority = -1
+    msgs = {
+        "W0011": (
+            "Relative import should be used",
+            "hass-relative-import",
+            "Used when absolute import should be replaced with relative import",
+        ),
+    }
+    options = ()
+
+    def __init__(self, linter: PyLinter | None = None) -> None:
+        super().__init__(linter)
+        self.current_module: str | None = None
+
+    def visit_module(self, node: Module) -> None:
+        """Called when a Import node is visited."""
+        self.current_module = node.name
+
+    def visit_import(self, node: Import) -> None:
+        """Called when a Import node is visited."""
+        for module, _alias in node.names:
+            if module.startswith(f"{self.current_module}."):
+                self.add_message("hass-relative-import", node=node)
+
+    def visit_importfrom(self, node: ImportFrom) -> None:
+        """Called when a ImportFrom node is visited."""
+        if node.level is not None:
+            return
+        if node.modname == self.current_module or node.modname.startswith(
+            f"{self.current_module}."
+        ):
+            self.add_message("hass-relative-import", node=node)
+
+
+def register(linter: PyLinter) -> None:
+    """Register the checker."""
+    linter.register_checker(HassImportsFormatChecker(linter))