tests: Skip subinterpreter tests on iOS, add pytest timeout

- Add `IOS` platform constant to `tests/env.py` for consistency with
  existing `ANDROID`, `LINUX`, `MACOS`, `WIN`, `FREEBSD` constants.

- Skip `test_multiple_interpreters.py` module on iOS. Subinterpreters
  are not supported in the iOS simulator environment. These tests were
  previously skipped implicitly because the modules weren't installed
  in the wheel; now that they are (commit 6ed6d5a), we need an
  explicit skip.

- Change pytest timeout from 0 (disabled) to 120 seconds. This provides
  a safety net to catch hanging tests before the CI job times out after
  hours. Normal test runs complete in 33-55 seconds total (~1100 tests),
  so 120 seconds per test is very generous.

- Add `-v` flag for verbose output to help diagnose any future issues.

Author: rwgk

tests/env.py

@@ -5,6 +5,7 @@
 import sysconfig
 
 ANDROID = sys.platform.startswith("android")
+IOS = sys.platform.startswith("ios")
 LINUX = sys.platform.startswith("linux")
 MACOS = sys.platform.startswith("darwin")
 WIN = sys.platform.startswith("win32") or sys.platform.startswith("cygwin")

tests/pyproject.toml

@@ -27,7 +27,7 @@ PYBIND11_FINDPYTHON = true
 
 [tool.cibuildwheel]
 test-sources = ["tests", "pyproject.toml"]
-test-command = "python -m pytest -v -o timeout=0 -p no:cacheprovider tests"
+test-command = "python -m pytest -v -o timeout=120 -p no:cacheprovider tests"
 environment.PIP_ONLY_BINARY = "numpy"
 environment.PIP_PREFER_BINARY = "1"
 

tests/test_multiple_interpreters.py

@@ -9,8 +9,12 @@
 
 import pytest
 
+import env
 import pybind11_tests
 
+if env.IOS:
+    pytest.skip("Subinterpreters not supported on iOS", allow_module_level=True)
+
 # 3.14.0b3+, though sys.implementation.supports_isolated_interpreters is being added in b4
 # Can be simplified when we drop support for the first three betas
 CONCURRENT_INTERPRETERS_SUPPORT = (