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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Some tests fail when __pycache__ prefix is set","articleBody":"# Bug report\n\n### Bug description:\n\nSome tests that check .pyc files creation are failing when `sys.pycache_prefix` is set.\n\nList of tests that failed on Arm64 MacOS (maybe there's more in skipped ones):\n- [ ] `test.test_inspect.test_inspect.TestModuleCLI.test_details_option_with_package`\n- [ ] `test.test_import.PycacheTests.test_import_pyc_path`\n- [ ] `test.test_import.PycacheTests.test_unwritable_directory`\n- [ ] `test.test_importlib.test_util.PEP3147Tests.test_cache_from_source`\n- [ ] `test.test_importlib.test_util.PEP3147Tests.test_cache_from_source_cwd`\n- [ ] `test.test_importlib.test_util.PEP3147Tests.test_cache_from_source_no_dot`\n- [ ] `test.test_importlib.test_util.PEP3147Tests.test_cache_from_source_optimization_None`\n- [ ] `test.test_importlib.test_util.PEP3147Tests.test_cache_from_source_optimization_empty_string`\n- [ ] `test.test_importlib.test_util.PEP3147Tests.test_cache_from_source_optimization_set`\n- [ ] `test.test_importlib.test_util.PEP3147Tests.test_cache_from_source_path_like_arg`\n- [ ] `test.test_py_compile.PyCompileCLITestCase.test_with_files`\n- [ ] `test.test_py_compile.PyCompileTestsBase.test_double_dot_no_clobber`\n- [ ] `test.test_compileall.CompileallTestsBase.test_include_on_stdin`\n- [ ] `test.test_compileall.CompileallTestsBase.test_multiple_runs`\n- [ ] `test.test_compileall.CompileallTestsBase.test_symlink_loop`\n\nexample: `PYTHONPYCACHEPREFIX=\"$HOME/__pycache__\" ./python.exe -m test test.test_compileall test.test_import test.test_importlib.test_util test.test_inspect.test_inspect test.test_py_compile -v`\n\noutput (edited for clarity and length): [testres.txt](https://github.com/user-attachments/files/29077902/testres.txt)\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nmacOS\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-151952\n* gh-152736\n* gh-152744\n* gh-152748\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/ringobanana-3900","@type":"Person","name":"ringobanana-3900"},"datePublished":"2026-06-18T07:46:29.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/151626/cpython/issues/151626"}