refactor: replace black, isort and pylint with ruff

.github/workflows/formatting.yml

@@ -3,18 +3,27 @@ name: "Formatting"
 on: [push]
 jobs:
   black:
+    # job id and matrix "tool" values are kept as black/isort on purpose: they're the required
+    # status check names configured in the repo's branch ruleset ("black (black)", "black
+    # (isort)"). The command each value runs is now ruff, not the tool the label names -
+    # renaming the labels requires updating the ruleset's required-check list in the same change.
+    name: "black (${{ matrix.tool }})"
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        tool: ["black", "isort"]
+        include:
+          - tool: black
+            command: "ruff format --check ."
+          - tool: isort
+            command: "ruff check --select I ."
     steps:
       - uses: actions/checkout@v7
       - name: Install uv
         uses: astral-sh/setup-uv@v9.0.0
         with:
           python-version: "3.14"
       - name: Install dependencies
-        run: uv sync --group formatting
+        run: uv sync --group linting
       - name: ${{ matrix.tool }} Code Formatter
         run: |
-          uv run --group formatting ${{ matrix.tool }} . --check
+          uv run --group linting ${{ matrix.command }}

.github/workflows/pythonlint.yml

@@ -19,8 +19,7 @@ jobs:
       - name: Run linting
         if: matrix.linter-env == 'linting'
         run: |
-          uv run --group linting pylint src/generics
-          uv run --group linting pylint unittests --rcfile=unittests/.pylintrc
+          uv run --group linting ruff check src/generics unittests
       - name: Run type_check
         if: matrix.linter-env == 'type_check'
         run: |

.pre-commit-config.yaml

@@ -10,19 +10,10 @@ repos:
       - id: check-yaml
       - id: end-of-file-fixer
       - id: trailing-whitespace
-  - repo: https://github.com/psf/black
-    rev: 26.5.1
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.16.0
     hooks:
-      - id: black
-        language_version: python3
-  - repo: https://github.com/pycqa/isort
-    rev: 8.0.1
-    hooks:
-      - id: isort
-        name: isort (python)
-      - id: isort
-        name: isort (cython)
-        types: [cython]
-      - id: isort
-        name: isort (pyi)
-        types: [pyi]
+      - id: ruff-check
+        args: [--fix]
+        files: ^(src/generics|unittests)/
+      - id: ruff-format

README.md

@@ -3,7 +3,7 @@
 ![Unittests status badge](https://github.com/Hochfrequenz/python-generics/workflows/Unittests/badge.svg)
 ![Coverage status badge](https://github.com/Hochfrequenz/python-generics/workflows/Coverage/badge.svg)
 ![Linting status badge](https://github.com/Hochfrequenz/python-generics/workflows/Linting/badge.svg)
-![Black status badge](https://github.com/Hochfrequenz/python-generics/workflows/Formatting/badge.svg)
+![Formatting status badge](https://github.com/Hochfrequenz/python-generics/workflows/Formatting/badge.svg)
 
 Ever wondered how to do something like this?
 

pyproject.toml

@@ -26,17 +26,30 @@ dynamic = ["readme", "version"]
 Changelog = "https://github.com/Hochfrequenz/python-generics/releases"
 Homepage = "https://github.com/Hochfrequenz/python-generics"
 
-[tool.black]
+[tool.ruff]
 line-length = 120
-target_version = ["py310", "py311", "py312", "py313", "py314"]
+target-version = "py310"
+extend-exclude = ["*.md"]
 
-[tool.isort]
-line_length = 120
-profile = "black"
+[tool.ruff.per-file-target-version]
+"unittests/test_py_312.py" = "py312"
 
-[tool.pylint."MESSAGES CONTROL"]
-max-line-length = 120
-disable = "fixme,too-few-public-methods"
+[tool.ruff.lint]
+select = ["E", "W", "F", "I", "UP", "B", "N", "PL", "RUF"]
+ignore = [
+    "PLR0912", # too-many-branches
+    "PLR0913", # too-many-arguments
+    "PLR0915", # too-many-statements
+    "PLR0917", # too-many-positional-arguments
+    "PLR2004", # magic-value-comparison
+]
+
+[tool.ruff.lint.per-file-ignores]
+# unittests/.pylintrc disabled invalid-name repo-wide for this directory: tests use single
+# uppercase letters (A, B, C, ...) as class/type-alias names to mirror TypeVar conventions.
+"unittests/*" = ["N"]
+
+[tool.ruff.format]
 
 [tool.codespell]
 skip = "uv.lock"
@@ -51,7 +64,7 @@ coverage = [
     {include-group = "tests"}
 ]
 linting = [
-    "pylint==4.0.6",
+    "ruff==0.16.0",
     {include-group = "tests"}
 ]
 type_check = [
@@ -61,17 +74,12 @@ type_check = [
 spellcheck = [
     "codespell==2.4.3"
 ]
-formatting = [
-    "black==26.5.1",
-    "isort==8.0.1"
-]
 dev = [
     {include-group = "tests"},
     {include-group = "coverage"},
     {include-group = "linting"},
     {include-group = "type_check"},
     {include-group = "spellcheck"},
-    {include-group = "formatting"},
     "pre-commit"
 ]
 

src/generics/__init__.py

@@ -6,11 +6,9 @@
 is no need to support this edge case.
 """
 
-from typing import Any, Generic
+from typing import Any, Generic, Protocol, TypeVar, get_args, get_origin
 from typing import GenericAlias as TypesGenericAlias  # type: ignore[attr-defined]
-from typing import Optional, Protocol, TypeVar, Union
 from typing import _GenericAlias as TypingGenericAlias  # type: ignore[attr-defined]
-from typing import get_args, get_origin
 
 
 class GenericType(Protocol):
@@ -22,7 +20,7 @@ class GenericType(Protocol):
     __orig_bases__: tuple[type, ...]
 
 
-def get_type_vars(type_: Union[type, GenericType]) -> tuple[TypeVar, ...]:
+def get_type_vars(type_: type | GenericType) -> tuple[TypeVar, ...]:
     """
     For a given generic type, return a tuple of its type variables. The type variables are collected through the
     supertypes arguments `Generic` if present.
@@ -73,7 +71,7 @@ def get_type_vars(type_: Union[type, GenericType]) -> tuple[TypeVar, ...]:
     return tuple(type_vars)
 
 
-def _generic_metaclass_executed_on_type(type_: Union[type, GenericType]) -> bool:
+def _generic_metaclass_executed_on_type(type_: type | GenericType) -> bool:
     """
     This function determines if the type was processed by a `_GenericAlias` with all its `__mro_entries__` magic.
     I.e. if the type has `Generic` as supertype or something like `A[T]` in its supertypes.
@@ -93,25 +91,25 @@ def _generic_metaclass_executed_on_type(type_: Union[type, GenericType]) -> bool
     # variables.
 
 
-def _find_super_type_trace(type_: type, search_for_type: type) -> Optional[list[type]]:
+def _find_super_type_trace(type_: type, search_for_type: type) -> list[type] | None:
     """
     This function returns a list of ancestors tracing from `type_` to `search_for_type`.
     The list is ordered from `type_` to `search_for_type`. If `search_for_type` is not a supertype of
     `type_`, `None` is returned.
     """
     if type_ == search_for_type:
         return [type_]
-    if type_ == object:
+    if type_ is object:
         return None
     for base in type_.__bases__:
         super_type_trace = _find_super_type_trace(base, search_for_type)
         if super_type_trace is not None:
-            return [type_] + super_type_trace
+            return [type_, *super_type_trace]
     return None
 
 
 def _process_inputs_of_get_filled_type(
-    type_or_instance: Any, type_var_defining_super_type: type, type_var_or_position: Union[TypeVar, int]
+    type_or_instance: Any, type_var_defining_super_type: type, type_var_or_position: TypeVar | int
 ) -> tuple[type, type, int]:
     """
     This function processes the inputs of `get_filled_type`. It returns a tuple of the filled type, the super type and
@@ -142,7 +140,7 @@ def _process_inputs_of_get_filled_type(
 
 # pylint: disable=too-many-branches, too-many-locals
 def get_filled_type(
-    type_or_instance: Any, type_var_defining_super_type: type, type_var_or_position: Union[TypeVar, int]
+    type_or_instance: Any, type_var_defining_super_type: type, type_var_or_position: TypeVar | int
 ) -> Any:
     """
     Determines the type of the `type_var_or_position` defined by the type `type_var_defining_super_type`.
@@ -190,10 +188,9 @@ def get_filled_type(
         for orig_base in type_.__orig_bases__:  # type: ignore[attr-defined]
             if get_origin(orig_base) == type_trace[-reversed_index + 1]:
                 orig_base_args = get_args(orig_base)
-                if len(orig_base_args) < type_var_index:
+                if len(orig_base_args) <= type_var_index:
                     raise TypeError(
-                        f"Could not determine the type in {filled_type!r}: "
-                        f"{orig_base!r} has not enough type arguments"
+                        f"Could not determine the type in {filled_type!r}: {orig_base!r} has not enough type arguments"
                     )
                 type_var_replacement = orig_base_args[type_var_index]
                 if not isinstance(type_var_replacement, TypeVar):
@@ -206,9 +203,9 @@ def get_filled_type(
         raise TypeError(f"Could not determine the type in {filled_type!r}: The value of the TypeVar is undefined")
 
     filled_type_args = get_args(filled_type)
-    if len(filled_type_args) < type_var_index:
+    if len(filled_type_args) <= type_var_index:
         raise TypeError(
-            f"Could not determine the type in {filled_type!r}: " f"{filled_type!r} has not enough type arguments"
+            f"Could not determine the type in {filled_type!r}: {filled_type!r} has not enough type arguments"
         )
 
     return filled_type_args[type_var_index]

unittests/test_get_filled_type.py

@@ -2,7 +2,7 @@
 A module with unit tests for the `get_filled_type` function.
 """
 
-from typing import Any, Generic, List, TypeVar
+from typing import Any, Generic, TypeVar
 
 import pytest
 from pydantic import BaseModel
@@ -68,7 +68,7 @@ class B(A[T]):
         class C(Generic[U]):
             pass
 
-        class D(B[Z], C[int], List[U], Generic[U, Z]):
+        class D(B[Z], C[int], list[U], Generic[U, Z]):
             pass
 
         assert get_filled_type(D[int, str], A, T) is str
@@ -121,7 +121,7 @@ class B(A[T]):
         class C(Generic[U]):
             pass
 
-        class D(B[Z], C[int], List[U], Generic[U, Z]):
+        class D(B[Z], C[int], list[U], Generic[U, Z]):
             pass
 
         d = D[int, str]()
@@ -146,7 +146,7 @@ class B(A[T]):
         class C(Generic[U]):
             pass
 
-        class D(B[Z], C[int], List[U], Generic[U, Z]):
+        class D(B[Z], C[int], list[U], Generic[U, Z]):
             pass
 
         E = D[int, T]
@@ -258,7 +258,7 @@ def get_type(self) -> Any:
         class MySubType(MySuperType[str]):
             pass
 
-        assert MySubType().get_type() == str
+        assert MySubType().get_type() is str
 
     def test_builtin_list_as_supertype(self):
         """