Optional pytype install on Windows (no CI) (#12669)

tests/README.md

@@ -71,9 +71,7 @@ for this script.
 
 ## pytype\_test.py
 
-Note: this test cannot be run on Windows
-systems unless you are using Windows Subsystem for Linux.
-It also requires a Python version < 3.13 as pytype does not yet support
+Note: This test cannot be run on Python version < 3.13 as pytype does not yet support
 Python 3.13 and above.
 
 Run using:

tests/pytype_test.py

@@ -14,30 +14,32 @@ will also discover incorrect usage of imported modules.
 
 from __future__ import annotations
 
+import sys
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    assert sys.platform != "win32", "pytype isn't yet installed in CI, but wheels can be built on Windows"
+if sys.version_info >= (3, 13):
+    print("pytype does not support Python 3.13+ yet.", file=sys.stderr)
+    sys.exit(1)
+
+
 import argparse
 import importlib.metadata
 import inspect
 import os
-import sys
 import traceback
 from collections.abc import Iterable, Sequence
 
 from packaging.requirements import Requirement
 
-from _metadata import read_dependencies
-from _utils import SupportedVersionsDict, parse_stdlib_versions_file, supported_versions_for_module
-
-if sys.platform == "win32":
-    print("pytype does not support Windows.", file=sys.stderr)
-    sys.exit(1)
-if sys.version_info >= (3, 13):
-    print("pytype does not support Python 3.13+ yet.", file=sys.stderr)
-    sys.exit(1)
-
 # pytype is not py.typed https://github.com/google/pytype/issues/1325
 from pytype import config as pytype_config, load_pytd  # type: ignore[import]
 from pytype.imports import typeshed  # type: ignore[import]
 
+from _metadata import read_dependencies
+from _utils import SupportedVersionsDict, parse_stdlib_versions_file, supported_versions_for_module
+
 TYPESHED_SUBDIRS = ["stdlib", "stubs"]
 TYPESHED_HOME = "TYPESHED_HOME"
 _LOADERS = {}

tests/runtests.py

@@ -7,6 +7,7 @@ import os
 import re
 import subprocess
 import sys
+from importlib.util import find_spec
 from pathlib import Path
 from typing import Any
 
@@ -127,11 +128,11 @@ def main() -> None:
     else:
         print(colored("\nSkipping stubtest since mypy failed.", "yellow"))
 
-    if sys.platform == "win32":
-        print(colored("\nSkipping pytype on Windows. You can run the test with WSL.", "yellow"))
-    else:
+    if find_spec("pytype"):
         print("\nRunning pytype...")
         pytype_result = subprocess.run([sys.executable, "tests/pytype_test.py", path])
+    else:
+        print(colored("\nSkipping pytype on Windows. You need to install it first: `pip install pytype`.", "yellow"))
 
     cases_path = test_cases_path(stub if folder == "stubs" else "stdlib")
     if not cases_path.exists():

tests/typecheck_typeshed.py

@@ -69,8 +69,6 @@ def run_mypy_as_subprocess(directory: str, platform: str, version: str) -> Retur
         "--custom-typeshed-dir",
         ".",
     ]
-    if directory == "tests" and platform == "win32":
-        command.extend(["--exclude", "tests/pytype_test.py"])
     result = subprocess.run(command, capture_output=True, text=True)
     if result.stderr:
         print_error(result.stderr)