python-attrs · hynek · Sep 28, 2025 · Sep 28, 2025 · Sep 28, 2025 · Sep 28, 2025
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -179,8 +179,8 @@ jobs:
 
       - run: uvx --with=tox-uv tox run -e docs-doctests,changelog
 
-  pyright:
-    name: Check types using pyright
+  typing:
+    name: Check types using supported type checkers
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
@@ -191,7 +191,7 @@ jobs:
       - run: >
           uvx --with=tox-uv
           --python $(cat .python-version-default)
-          tox run -e pyright
+          tox run -f typing
 
   install-dev:
     name: Verify dev env
@@ -222,7 +222,7 @@ jobs:
       - tests-pypy
       - docs
       - install-dev
-      - pyright
+      - typing
 
     runs-on: ubuntu-latest
 

diff --git a/pyproject.toml b/pyproject.toml
@@ -51,6 +51,8 @@ tests = [
 ]
 cov = [{ include-group = "tests" }, "coverage[toml]"]
 pyright = ["pyright", { include-group = "tests" }]
+ty = ["ty", { include-group = "tests" }]
+pyrefly = ["pyrefly", { include-group = "tests" }]
 benchmark = [
   { include-group = "tests" },
   "pytest-codspeed",
@@ -254,11 +256,12 @@ ignore = [
 
 "src/*/*.pyi" = ["ALL"] # TODO
 "tests/test_annotations.py" = ["FA100"]
-"tests/typing_example.py" = [
-  "E741",  # ambiguous variable names don't matter in type checks
-  "B018",  # useless expressions aren't useless in type checks
-  "B015",  # pointless comparison in type checks aren't pointless
-  "UP037", # we test some older syntaxes on purpose
+"typing-examples/*" = [
+  "INP001", # not for imports
+  "E741",   # ambiguous variable names don't matter in type checks
+  "B018",   # useless expressions aren't useless in type checks
+  "B015",   # pointless comparison in type checks aren't pointless
+  "UP037",  # we test some older syntaxes on purpose
 ]
 
 [tool.ruff.lint.isort]

diff --git a/tox.ini b/tox.ini
@@ -1,11 +1,14 @@
+# SPDX-License-Identifier: MIT
+
 [tox]
 min_version = 4
 env_list =
     pre-commit,
     py3{9,10,11,12,13,14}-tests,
     py3{10,11,12,13,14}-mypy,
     pypy3-tests,
-    pyright,
+    # Mypy needs to run within the respective Python version
+    typing-{pyright,ty,pyrefly}
     docs-{sponsors,doctests},
     changelog,
     coverage-combine,
@@ -26,7 +29,7 @@ dependency_groups =
 commands =
     tests: pytest {posargs:-n auto}
     mypy: pytest -k test_mypy
-    mypy: mypy tests/typing_example.py
+    mypy: mypy typing-examples
     mypy: mypy src/attrs/__init__.pyi src/attr/__init__.pyi src/attr/_typing_compat.pyi src/attr/_version_info.pyi src/attr/converters.pyi src/attr/exceptions.pyi src/attr/filters.pyi src/attr/setters.pyi src/attr/validators.pyi
 
 [testenv:pypy3-tests]
@@ -121,9 +124,19 @@ commands =
     towncrier build --version main --draft
 
 
-[testenv:pyright]
+[testenv:typing-pyright]
 dependency_groups = pyright
-commands = pytest tests/test_pyright.py -vv
+commands =
+    pyright typing-examples/baseline_examples.py
+    pytest tests/test_pyright.py -vv
+
+[testenv:typing-ty]
+dependency_groups = ty
+commands = ty check typing-examples/baseline_examples.py
+
+[testenv:typing-pyrefly]
+dependency_groups = pyrefly
+commands = pyrefly check typing-examples/baseline_examples.py
 
 
 [testenv:docset]

diff --git a/typing-examples/README.md b/typing-examples/README.md
@@ -0,0 +1,7 @@
+# Typing examples
+
+The files in this directory are **not** meant to be executed.
+
+They are type-checked using various type checkers to ensure our type stubs are correct.
+
+See the environments starting with `typing-` in [`tox.ini`](../tox.ini).
diff --git a/typing-examples/baseline_examples.py b/typing-examples/baseline_examples.py
@@ -0,0 +1,177 @@
+# SPDX-License-Identifier: MIT
+
+"""
+Baseline features that should be supported by all type checkers.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+import attrs
+
+
+@attrs.define(order=True)
+class NGClass:
+    x: int = attrs.field(default=42)
+
+
+ngc = NGClass(1)
+
+
+@attrs.mutable(slots=False)
+class NGClass2:
+    x: int
+
+
+ngc2 = NGClass2(1)
+
+
+@attrs.frozen(str=True)
+class NGFrozen:
+    x: int
+
+
+ngf = NGFrozen(1)
+
+attrs.fields(NGFrozen).x.evolve(eq=False)
+a = attrs.fields(NGFrozen).x
+a.evolve(repr=False)
+
+
+@attrs.define
+class C:
+    a: int
+
+
+c = C(1)
+c.a
+
+
+@attrs.frozen
+class D:
+    a: int
+
+
+D(1).a
+
+
+@attrs.define
+class Derived(C):
+    b: int
+
+
+Derived(1, 2).a
+Derived(1, 2).b
+
+
+@attrs.define
+class Error(Exception):
+    x: int
+
+
+try:
+    raise Error(1)
+except Error as e:
+    e.x
+    e.args
+    str(e)
+
+
+@attrs.define
+class AliasExample:
+    without_alias: int
+    _with_alias: int = attrs.field(alias="_with_alias")
+
+
+attrs.fields(AliasExample).without_alias.alias
+attrs.fields(AliasExample)._with_alias.alias
+
+
+@attrs.define
+class Validated:
+    num: int = attrs.field(validator=attrs.validators.ge(0))
+
+
+attrs.validators.set_disabled(True)
+attrs.validators.set_disabled(False)
+
+
+with attrs.validators.disabled():
+    Validated(num=-1)
+
+
+@attrs.define
+class WithCustomRepr:
+    a: int = attrs.field(repr=True)
+    b: str = attrs.field(repr=False)
+    c: str = attrs.field(repr=lambda value: "c is for cookie")
+    d: bool = attrs.field(repr=str)
+
+
+@attrs.define(on_setattr=attrs.setters.validate)
+class ValidatedSetter2:
+    a: int
+    b: str = attrs.field(on_setattr=attrs.setters.NO_OP)
+    c: bool = attrs.field(on_setattr=attrs.setters.frozen)
+    d: int = attrs.field(
+        on_setattr=[attrs.setters.convert, attrs.setters.validate]
+    )
+    e: bool = attrs.field(
+        on_setattr=attrs.setters.pipe(
+            attrs.setters.convert, attrs.setters.validate
+        )
+    )
+
+
+@attrs.define(eq=True, order=True)
+class OrderFlags:
+    a: int = attrs.field(eq=False, order=False)
+    b: int = attrs.field(eq=True, order=True)
+
+
+# field_transformer
+def ft_hook2(
+    cls: type, attribs: list[attrs.Attribute]
+) -> list[attrs.Attribute]:
+    return attribs
+
+
+@attrs.define(field_transformer=ft_hook2)
+class TransformedAttrs2:
+    x: int
+
+
+@attrs.define
+class FactoryTest:
+    a: list[int] = attrs.field(default=attrs.Factory(list))
+    b: list[Any] = attrs.field(default=attrs.Factory(list, False))
+    c: list[int] = attrs.field(default=attrs.Factory((lambda s: s.a), True))
+
+
+attrs.asdict(FactoryTest())
+attrs.asdict(FactoryTest(), retain_collection_types=False)
+
+
+@attrs.define(match_args=False)
+class MatchArgs2:
+    a: int
+    b: int
+
+
+# NG versions of asdict/astuple
+attrs.asdict(MatchArgs2(1, 2))
+attrs.astuple(MatchArgs2(1, 2))
+
+
+def accessing_from_attrs() -> None:
+    """
+    Use a function to keep the ns clean.
+    """
+    attrs.converters.optional
+    attrs.exceptions.FrozenError
+    attrs.filters.include
+    attrs.filters.exclude
+    attrs.setters.frozen
+    attrs.validators.and_
+    attrs.cmp_using