Format using ruff

.github/workflows/main.yml

@@ -108,7 +108,7 @@ jobs:
       - uses: hynek/setup-cached-uv@757bedc3f972eb7227a1aa657651f15a8527c817
 
       - name: "Build package"
-        run: "uvx pdm build"
+        run: "uv build"
       - name: "List result"
         run: "ls -l dist"
       - name: "Check wheel contents"

.gitignore

@@ -67,4 +67,3 @@ settings.json
 .editorconfig
 .mypy_cache
 .pytest_cache
-.pdm-python

HISTORY.md

@@ -20,6 +20,8 @@ Our backwards-compatibility policy can be found [here](https://github.com/python
   ([#728](https://github.com/python-attrs/cattrs/pull/728))
 - Fix the `detailed_validation` parameter being passed under the wrong name in {func}`namedtuple_dict_structure_factory <cattrs.cols.namedtuple_dict_structure_factory>`, causing it to be silently ignored.
   ([#723](https://github.com/python-attrs/cattrs/pull/723))
+- _cattrs_ is now autoformatted using Ruff.
+  ([#732](https://github.com/python-attrs/cattrs/pull/732))
 
 ## 26.1.0 (2026-02-18)
 

Justfile

@@ -7,7 +7,7 @@ sync version="":
 
 lint:
 	uv run -p python3.14 --group lint ruff check src/ tests bench
-	uv run -p python3.14 --group lint black --check src tests docs/conf.py
+	uv run -p python3.14 --group lint ruff format --check src tests docs/conf.py
 
 test *args="-x --ff -n auto tests":
     uv run {{ if python != '' { '-p ' + python } else { '' } }} --all-extras --group test --group lint pytest {{args}}

pyproject.toml

@@ -1,9 +1,5 @@
-[tool.black]
-skip-magic-trailing-comma = true
-
 [dependency-groups]
 lint = [
-    "black>=25.1.0",
     "ruff>=0.12.2",
 ]
 test = [
@@ -148,7 +144,7 @@ select = [
     "I",   # isort
 ]
 ignore = [
-    "E501",   # line length is handled by black
+    "E501",   # line length is handled by the formatter
     "RUF001", # leave my smart characters alone
     "S101",   # assert
     "S307",   # hands off my eval
@@ -161,14 +157,19 @@ ignore = [
     "UP006",  # We support old typing constructs at runtime
     "UP007",  # We support old typing constructs at runtime
     "UP035",  # We support old typing constructs at runtime
-    "UP038",  # Dubious rule
     "UP045",  # We support old typing constructs at runtime
 ]
 
 [tool.ruff.lint.pyupgrade]
 # Preserve types, even if a file imports `from __future__ import annotations`.
 keep-runtime-typing = true
 
+[tool.ruff.lint.isort]
+split-on-trailing-comma = false
+
+[tool.ruff.format]
+skip-magic-trailing-comma = true
+
 [tool.hatch.version]
 source = "vcs"
 raw-options = { local_scheme = "no-local-version" }

src/cattrs/cols.py

@@ -178,7 +178,6 @@ def structure_tuple(obj: Iterable[T], _: type = type) -> tuple[T, ...]:
         handler = converter.structure
 
     if converter.detailed_validation:
-
         # We have to structure into a list first anyway.
         list_structure = list_structure_factory(type, converter)
 

tests/preconf/test_pyyaml.py

@@ -16,7 +16,6 @@
 
 @given(everythings())
 def test_pyyaml(everything: Everything):
-
     converter = make_converter()
     unstructured = converter.unstructure(everything)
     raw = safe_dump(unstructured)

tests/test_disambiguators.py

@@ -162,7 +162,7 @@ class A:
 def test_disambiguation(cl_and_vals_a, cl_and_vals_b):
     """Disambiguation should work when there are unique required fields."""
     cl_a, vals_a, kwargs_a = cl_and_vals_a
-    cl_b, vals_b, kwargs_b = cl_and_vals_b
+    cl_b, _, _ = cl_and_vals_b
     c = Converter()
 
     req_a = {a.name for a in fields(cl_a)}

tests/test_generics.py

@@ -175,7 +175,7 @@ def test_raises_if_no_generic_params_supplied(
 
     with pytest.raises(
         StructureHandlerNotFoundError,
-        match="Unsupported type: ~T. Register a structure hook for it.|Missing type for generic argument T, specify it when structuring.",
+        match=r"Unsupported type: ~T. Register a structure hook for it.|Missing type for generic argument T, specify it when structuring.",
     ) as exc:
         converter.structure(asdict(data), TClass)
 
@@ -320,7 +320,6 @@ class Outer(Generic[T]):
 
 @pytest.mark.skipif(not is_py311_plus, reason="3.11+ only")
 def test_generate_typeddict_mapping() -> None:
-
     T = TypeVar("T")
     U = TypeVar("U")
 

tests/test_preconf.py

@@ -798,7 +798,6 @@ class A:
     booleans(),
 )
 def test_tomllib_converter(everything: Everything, detailed_validation: bool):
-
     converter = tomllib_make_converter(detailed_validation=detailed_validation)
     raw = converter.dumps(everything)
 

tests/test_structure.py

@@ -211,7 +211,7 @@ def test_structuring_dicts_opts(dict_and_type, data):
 @given(dicts_of_primitives)
 def test_stringifying_dicts(dict_and_type):
     converter = BaseConverter()
-    d, t = dict_and_type
+    d, _ = dict_and_type
 
     converted = converter.structure(d, Dict[str, str])
 
@@ -267,7 +267,7 @@ def test_structuring_lists_of_opt(list_and_type, detailed_validation: bool) -> N
 def test_stringifying_lists_of_opt(list_and_type):
     """Test structuring Optional primitive types into strings."""
     converter = BaseConverter()
-    lst, t = list_and_type
+    lst, _ = list_and_type
 
     lst.append(None)
 

tests/test_structure_attrs.py

@@ -86,7 +86,7 @@ def test_structure_union(cl_and_vals_a, cl_and_vals_b):
     """Structuring of automatically-disambiguable unions works."""
     converter = BaseConverter()
     cl_a, vals_a, kwargs_a = cl_and_vals_a
-    cl_b, vals_b, kwargs_b = cl_and_vals_b
+    cl_b, _, _ = cl_and_vals_b
     a_field_names = {a.name for a in fields(cl_a)}
     b_field_names = {a.name for a in fields(cl_b)}
     assume(a_field_names)
@@ -126,7 +126,7 @@ def test_structure_union_explicit(cl_and_vals_a, cl_and_vals_b):
     """Structuring of manually-disambiguable unions works."""
     converter = BaseConverter()
     cl_a, vals_a, kwargs_a = cl_and_vals_a
-    cl_b, vals_b, kwargs_b = cl_and_vals_b
+    cl_b, _, _ = cl_and_vals_b
 
     def dis(obj, _):
         return converter.structure(obj, cl_a)

tests/typeddicts.py

@@ -237,7 +237,7 @@ def generic_typeddicts(draw: DrawFn, total: bool = True) -> tuple[TypedDictType,
     actual_types = []
     for ix, (attr_name, attr_type) in enumerate(list(attrs_dict.items())):
         if ix in generic_attrs:
-            typevar = TypeVar(f"T{ix+1}")
+            typevar = TypeVar(f"T{ix + 1}")
             generics.append(typevar)
             if total and draw(booleans()):
                 # We might decide to make these NotRequired