Two CI tests for the new `--yes` update flag (#18261) flaked under
`pytest-xdist` on Linux/Python 3.11 even though they passed every
local run on macOS/Python 3.14.4:
FAILED tests/hermes_cli/test_update_yes_flag.py
::TestUpdateYesConfigMigration::test_no_yes_flag_still_prompts_in_tty
`AssertionError: assert <MagicMock 'input'>.called is False`
FAILED tests/hermes_cli/test_update_yes_flag.py
::TestUpdateYesStashRestore::test_yes_restores_stash_without_prompting
`AssertionError: assert <MagicMock '_restore_stashed_changes'>.called is False`
Captured stdout for the first failure shows `cmd_update` taking the
"Non-interactive session \u2014 skipping config migration prompt." branch
\u2014 i.e. the `sys.stdin.isatty() and sys.stdout.isatty()` check at
`hermes_cli/main.py:7118` evaluated to `False` despite the test doing:
with patch("hermes_cli.main.sys") as mock_sys:
mock_sys.stdin.isatty.return_value = True
mock_sys.stdout.isatty.return_value = True
The whole-module mock is fragile under xdist worker reuse: a sibling
test that imports `hermes_cli.main` first can leave another `sys`
reference resolved inside the function (re-import in a helper, etc.),
and the wholesale module replacement never gets consulted.
Switch to `patch.object(_sys.stdin, "isatty", return_value=True)` (and
the same for `stdout`). That patches the *attribute on the real stream
object* \u2014 every call site, no matter how it reached `sys.stdin`,
hits the patched method. Same fix applied to the stash-restore test
(it took the "non-TTY \u2192 skip restore prompt" branch for the same reason).
Validation:
$ pytest tests/hermes_cli/test_update_yes_flag.py -q
3 passed in 5.47s
No production code change. Fixes the two failures observed on `main`
(run 25250051126):
`tests/hermes_cli/test_update_yes_flag.py::TestUpdateYesConfigMigration::test_no_yes_flag_still_prompts_in_tty`
`tests/hermes_cli/test_update_yes_flag.py::TestUpdateYesStashRestore::test_yes_restores_stash_without_prompting`
Refs: #18261 (added the `--yes` flag + these tests).
Sanjay Santhanam
595bcc89fc