From d3f320e0cb3b4c74c29a2af8c1bd8d37ca724ed5 Mon Sep 17 00:00:00 2001
From: Hynek Schlawack <hs@ox.cx>
Date: Sun, 15 Dec 2024 06:45:26 +0100
Subject: [PATCH] typing: allow union types for instance_of (#1385)

* typing: allow union types for instance_of

fixes #1336

* Make hint meaningful albeit broken

* Stop running mypy on 3.9

* Declare bankruptcy

* Testing types only on 3.10+ now
---
 .github/workflows/ci.yml   | 2 +-
 changelog.d/1385.change.md | 2 ++
 pyproject.toml             | 4 ++--
 src/attr/validators.pyi    | 3 +++
 tests/typing_example.py    | 3 +++
 tox.ini                    | 2 +-
 6 files changed, 12 insertions(+), 4 deletions(-)
 create mode 100644 changelog.d/1385.change.md

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6b025d69c..339569881 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -66,7 +66,7 @@ jobs:
         run: |
           DO_MYPY=1
 
-          if [[ "$V" == "3.8" ]]; then
+          if [[ "$V" == "3.8" || "$V" == "3.9" ]]; then
             DO_MYPY=0
           fi
 
diff --git a/changelog.d/1385.change.md b/changelog.d/1385.change.md
new file mode 100644
index 000000000..cccfe5243
--- /dev/null
+++ b/changelog.d/1385.change.md
@@ -0,0 +1,2 @@
+`attrs.validators.instance_of()`'s type hints now allow for union types.
+For example: `instance_of(str | int)`
diff --git a/pyproject.toml b/pyproject.toml
index 0c981e3d0..0b598099f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -30,10 +30,10 @@ dynamic = ["version", "readme"]
 
 [project.optional-dependencies]
 tests-mypy = [
-  'pytest-mypy-plugins; platform_python_implementation == "CPython" and python_version >= "3.9"',
+  'pytest-mypy-plugins; platform_python_implementation == "CPython" and python_version >= "3.10"',
   # Since the mypy error messages keep changing, we have to keep updating this
   # pin.
-  'mypy>=1.11.1; platform_python_implementation == "CPython" and python_version >= "3.9"',
+  'mypy>=1.11.1; platform_python_implementation == "CPython" and python_version >= "3.10"',
 ]
 tests = [
   # For regression test to ensure cloudpickle compat doesn't break.
diff --git a/src/attr/validators.pyi b/src/attr/validators.pyi
index a04d43e14..a0fdda7c8 100644
--- a/src/attr/validators.pyi
+++ b/src/attr/validators.pyi
@@ -1,3 +1,4 @@
+from types import UnionType
 from typing import (
     Any,
     AnyStr,
@@ -44,6 +45,8 @@ def instance_of(
 ) -> _ValidatorType[_T1 | _T2 | _T3]: ...
 @overload
 def instance_of(type: tuple[type, ...]) -> _ValidatorType[Any]: ...
+@overload
+def instance_of(type: UnionType) -> _ValidatorType[Any]: ...
 def optional(
     validator: (
         _ValidatorType[_T]
diff --git a/tests/typing_example.py b/tests/typing_example.py
index cfeb95188..b8d414ba8 100644
--- a/tests/typing_example.py
+++ b/tests/typing_example.py
@@ -228,6 +228,9 @@ class Validated:
     k: int | str | C = attr.ib(
         validator=attrs.validators.instance_of((int, C, str))
     )
+    kk: int | str | C = attr.ib(
+        validator=attrs.validators.instance_of(int | C | str)
+    )
 
     l: Any = attr.ib(
         validator=attr.validators.not_(attr.validators.in_("abc"))
diff --git a/tox.ini b/tox.ini
index b1250f06c..4ccf8fe23 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,7 +3,7 @@ min_version = 4
 env_list =
     pre-commit,
     py3{8,9,10,11,12,13}-tests,
-    py3{9,10,11,12,13}-mypy,
+    py3{10,11,12,13}-mypy,
     pypy3,
     pyright,
     docs{,-sponsors},