ty as yet another type checker

.pre-commit-config.yaml

@@ -121,6 +121,11 @@ repos:
           - "types-docutils"
           - "types-lxml"
 
+  - repo: https://github.com/astral-sh/ty-pre-commit
+    rev: v0.0.59
+    hooks:
+      - id: ty
+
   - repo: https://github.com/python-jsonschema/check-jsonschema
     rev: "0.37.3"
     hooks:

pyproject.toml

@@ -298,6 +298,39 @@ reportPrivateUsage = false
 reportUnknownMemberType = false
 reportUnnecessaryCast = false  # Unnecessary "cast" call; type is already...
 
+[tool.ty]
+environment.root = ["./tmt"]
+
+[tool.ty.rules]
+# TODO: ty is very much in its Beta stage, not ready for production.
+# Disabling all rules that fail, for the sake of experiment, and will
+# enable them one by one when the tool becomes ready.
+unresolved-attribute = "ignore"
+unknown-argument = "ignore"
+unresolved-reference = "ignore"
+invalid-argument-type = "ignore"
+invalid-return-type = "ignore"
+no-matching-overload = "ignore"
+invalid-type-form = "ignore"
+not-subscriptable = "ignore"
+unsupported-operator = "ignore"
+possibly-missing-attribute = "ignore"
+invalid-assignment = "ignore"
+unresolved-import = "ignore"
+invalid-method-override = "ignore"
+unsupported-base = "ignore"
+invalid-key = "ignore"
+redundant-cast = "ignore"
+deprecated = "ignore"
+missing-argument = "ignore"
+too-many-positional-arguments = "ignore"
+invalid-yield = "ignore"
+possibly-missing-submodule = "ignore"
+invalid-generic-class = "ignore"
+call-top-callable = "ignore"
+inconsistent-mro = "ignore"
+invalid-legacy-type-variable = "ignore"
+
 [tool.ruff]
 line-length = 99
 src = ["tmt", "tests"]

tmt/guest/__init__.py

@@ -2462,7 +2462,7 @@ def execute(
         on_process_end: Optional[OnProcessEndCallback] = None,
         sourced_files: Optional[list[Path]] = None,
         **kwargs: Any,
-    ) -> tmt.utils.CommandOutput:
+    ) -> Optional[tmt.utils.CommandOutput]:
         """
         Execute a command on the guest.