Pyrefly typing tests

CONTRIBUTING.md

@@ -121,13 +121,14 @@ To run a subset of tests:
 $ just test tests/test_unstructure.py
 ```
 
-Static typing tests live in `tests/test_typing_structure.md` and run through `pytest-typing` with Mypy on CPython 3.14.
+Static typing tests live in `tests/test_typing_structure.md` and run through `pytest-typing` with Mypy and Pyrefly on CPython 3.14.
 To run them on their own:
 
 ```shell
 $ just --set python python3.14 test tests/test_typing_structure.md
 ```
 
-The test dependencies include a Mypy version with `TypeForm` support enabled by default.
+The test dependencies pin both checkers in `uv.lock`, including a Mypy version with `TypeForm` support enabled by default.
+`pytest-typing` is configured to use Pyrefly's `strict` preset for the temporary test snippets.
 
 [llm]: https://github.com/python-attrs/cattrs/blob/main/.github/AI_POLICY.md

pyproject.toml

@@ -7,6 +7,7 @@ test = [
     "pytest>=8.4.1",
     "pytest-typing; python_version == '3.14' and implementation_name == 'cpython'",
     "mypy; python_version == '3.14' and implementation_name == 'cpython'",
+    "pyrefly; python_version == '3.14' and implementation_name == 'cpython'",
     "pytest-benchmark>=5.1.0",
     "immutables>=0.21",
     "coverage>=7.9.2",
@@ -39,7 +40,8 @@ addopts = [
     "--benchmark-warmup-iterations=5",
     "--benchmark-group-by=fullname",
 ]
-typing_checkers = ["mypy"]
+typing_checkers = ["mypy", "pyrefly"]
+typing_pyrefly_preset = "strict"
 
 [project]
 name = "cattrs"

tests/test_typing_structure.md

@@ -6,6 +6,7 @@ These tests exercise the static return types for the structuring APIs.
 
 ```python
 from attrs import define
+from typing_extensions import assert_type
 
 from cattrs import structure
 
@@ -17,7 +18,7 @@ class User:
 
 
 user = structure({"id": 1, "name": "Ada"}, User)
-reveal_type(user)  # revealed: test_snippet.User
+assert_type(user, User)
 
 name: str = user.name
 ```
@@ -27,6 +28,8 @@ name: str = user.name
 ```python
 from dataclasses import dataclass
 
+from typing_extensions import assert_type
+
 from cattrs import Converter
 
 
@@ -38,7 +41,7 @@ class Point:
 
 converter = Converter()
 point = converter.structure({"x": 1, "y": 2}, Point)
-reveal_type(point)  # revealed: test_snippet.Point
+assert_type(point, Point)
 
 x: int = point.x
 ```
@@ -48,6 +51,8 @@ x: int = point.x
 ```python
 from typing import TypedDict
 
+from typing_extensions import assert_type
+
 from cattrs import Converter
 
 
@@ -58,33 +63,37 @@ class Movie(TypedDict):
 
 converter = Converter()
 movie = converter.structure({"title": "Alien", "year": 1979}, Movie)
-reveal_type(movie)  # revealed: TypedDict(test_snippet.Movie, {"title": str, "year": int})
+assert_type(movie, Movie)
 
 title: str = movie["title"]
 ```
 
 ## Converter structure returns homogeneous tuples
 
 ```python
+from typing_extensions import assert_type
+
 from cattrs import Converter
 
 
 converter = Converter()
 numbers = converter.structure([1, 2, 3], tuple[int, ...])
-reveal_type(numbers)  # revealed: tuple[int, ...]
+assert_type(numbers, tuple[int, ...])
 
 first: int = numbers[0]
 ```
 
 ## Converter structure returns heterogeneous tuples
 
 ```python
+from typing_extensions import assert_type
+
 from cattrs import Converter
 
 
 converter = Converter()
 row = converter.structure(["Ada", 37, True], tuple[str, int, bool])
-reveal_type(row)  # revealed: tuple[str, int, bool]
+assert_type(row, tuple[str, int, bool])
 
 name: str = row[0]
 age: int = row[1]
@@ -100,7 +109,9 @@ from cattrs import Converter
 converter = Converter()
 
 value: int = converter.structure("1", int)
-bad: str = converter.structure("1", int)  # mypy-error: [assignment]
+# mypy-error: [assignment]
+# pyrefly-error: [bad-assignment]
+bad: str = converter.structure("1", int)
 ```
 
 ## Hook factory decorators preserve factory types
@@ -109,6 +120,8 @@ bad: str = converter.structure("1", int)  # mypy-error: [assignment]
 from collections.abc import Callable
 from typing import Any
 
+from typing_extensions import assert_type
+
 from cattrs import Converter
 
 
@@ -129,8 +142,15 @@ def structure_factory(cl: type[int]) -> Callable[[str, type[int]], int]:
     return lambda value, _: int(value)
 
 
-reveal_type(unstructure_factory)  # revealed: def (cl: type[int]) -> def (int) -> str
-reveal_type(structure_factory)  # revealed: def (cl: type[int]) -> def (str, type[int]) -> int
+assert_type(unstructure_factory(cl=int), Callable[[int], str])
+assert_type(structure_factory(cl=int), Callable[[str, type[int]], int])
+
+# mypy-error: [arg-type]
+# pyrefly-error: [bad-argument-type]
+unstructure_factory(str)
+# mypy-error: [arg-type]
+# pyrefly-error: [bad-argument-type]
+structure_factory(str)
 ```
 
 ## Structure accepts type forms and preserves their result types
@@ -181,8 +201,12 @@ def convert(value: object, target: TypeForm[T]) -> T:
 
 assert_type(convert("1", int | None), int | None)
 
-bad: str = converter.structure("1", int | None)  # mypy-error: [assignment]
-converter.structure("1", 42)  # mypy-error: [arg-type]
+# mypy-error: [assignment]
+# pyrefly-error: [bad-assignment]
+bad: str = converter.structure("1", int | None)
+# mypy-error: [arg-type]
+# pyrefly-error: [bad-argument-type]
+converter.structure("1", 42)
 ```
 
 ## Structure hook lookup preserves type forms