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Fix flaky editable install tests: stale .pyc due to integer-second mtime race #5253

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Merged
jaraco merged 4 commits into from
Jul 4, 2026
Merged

Fix flaky editable install tests: stale .pyc due to integer-second mtime race #5253

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c095eec
Initial plan
Copilot Jul 4, 2026
c045461
Fix flaky editable tests: bump mtime after source writes to avoid sta…
Copilot Jul 4, 2026
3d86108
Remove redundant inline comment; docstring covers the context
Copilot Jul 4, 2026
45c53ba
👹 Feed the hobgoblins (delint).
jaraco Jul 4, 2026
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23 changes: 20 additions & 3 deletions setuptools/tests/test_editable_install.py
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Original file line number Diff line number Diff line change
Expand Up @@ -120,7 +120,6 @@ def editable_opts(request):
SETUP_SCRIPT_STUB = "__import__('setuptools').setup()"


@pytest.mark.xfail(sys.platform == "darwin", reason="pypa/setuptools#4328")
@pytest.mark.parametrize(
"files",
[
Expand Down Expand Up @@ -148,8 +147,10 @@ def test_editable_with_pyproject(tmp_path, venv, files, editable_opts):
cmd = ["python", "-m", "mypkg"]
assert venv.run(cmd).strip() == "3.14159.post0 Hello World"

mod_py = project / "src/mypkg/mod.py"
mod_py.write_text("x = 42", encoding="utf-8")
_advance_mtime(mod_py)
(project / "src/mypkg/data.txt").write_text("foobar", encoding="utf-8")
(project / "src/mypkg/mod.py").write_text("x = 42", encoding="utf-8")
assert venv.run(cmd).strip() == "3.14159.post0 foobar 42"


Expand Down Expand Up @@ -896,7 +897,6 @@ class TestOverallBehaviour:
},
}

@pytest.mark.xfail(sys.platform == "darwin", reason="pypa/setuptools#4328")
@pytest.mark.parametrize("layout", EXAMPLES.keys())
def test_editable_install(self, tmp_path, venv, layout, editable_opts):
project, _ = install_project(
Expand Down Expand Up @@ -939,6 +939,8 @@ def test_editable_install(self, tmp_path, venv, layout, editable_opts):
mod1.write_text("var = 17", encoding="utf-8")
mod2.write_text("var = 781", encoding="utf-8")
resource_file.write_text("resource 374", encoding="utf-8")
_advance_mtime(mod1)
_advance_mtime(mod2)

out = venv.run(["python", "-c", dedent(cmd_get_vars)])
assert "42 13" not in out
Expand Down Expand Up @@ -1259,3 +1261,18 @@ def assert_link_to(file: Path, other: Path) -> None:

def comparable_path(str_with_path: str) -> str:
return str_with_path.lower().replace(os.sep, "/").replace("//", "/")


def _advance_mtime(path: Path) -> None:
"""Advance a file's mtime by 2 seconds.

Python's .pyc bytecode-cache validation compares mtimes as integer seconds.
When a source file is written within the same wall-clock second that its
.pyc was compiled, the stored mtime equals the new mtime and Python reuses
the stale bytecode. Advancing the mtime by 2 seconds (rather than just 1)
provides a safety margin against rounding at second boundaries and
guarantees the .pyc is seen as out-of-date on the next import.
See pypa/setuptools#4328.
"""
st = path.stat()
os.utime(path, (st.st_atime + 2, st.st_mtime + 2))
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