Skip tests for subprocess

tests/test_custom_type_setup.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import gc
 import os
+import sys
 import weakref
 
 import pytest
@@ -51,6 +52,10 @@ def test_indirect_cycle(gc_tester):
     gc_tester(obj)
 
 
+@pytest.mark.skipif(
+    env.IOS or sys.platform.startswith("emscripten"),
+    reason="Requires subprocess support",
+)
 @pytest.mark.skipif("env.PYPY or env.GRAALPY")
 def test_py_cast_useable_on_shutdown():
     env.check_script_success_in_subprocess(