refactor(cli): assert the clap env hook is absent without mutating the environment

[sileht]

The two tests that pinned "clap must not read MERGIFY_* itself"
each exported one variable empty and parsed one argv. They were the
last two temp_env calls in mergify-cli, and the only ones whose
reader was a dependency rather than our own code.

They are two tests now, at the two altitudes the rule lives at. A
walk over the built clap::Command tree asserts that no argument
anywhere declares env = "…", which catches the hook at declaration
and covers every argument rather than --config and
--test-exit-code. A parse of each of those two argvs asserts the
observable property the deleted tests asserted, because the walk
only sees that one spelling: default_value_t = std::env::var(…).unwrap_or_default() reproduces monorepo#33423
exactly and declares no hook. Neither test needs an environment.

MERGIFY_BASE_URL joins the rest in treating exported-but-empty as
unset. install.sh already guards the same lever with [ -n … ], so
the two halves of one feature disagreed: an empty value built the URL
/latest-release.json, which reqwest rejects as relative, instead of
falling back to the default host.

The rest is plumbing: MERGIFY_CLI_TESTING_UTF8_MODE, NO_COLOR /
FORCE_COLOR / CLICOLOR_FORCE and self_update's
MERGIFY_BASE_URL read through mergify_core::env. That is the
env in scope in both files now; args() and current_exe() are
spelled std::env::, since neither is the environment.

Co-Authored-By: Claude Opus 5 noreply@anthropic.com

[sileht]

This pull request is part of a Mergify stack:

#	Pull Request	Link
1	refactor(cli): assert the clap env hook is absent without mutating the environment	#1841	👈
2	refactor(auth): read the environment through the funnel	#1842
3	chore(lint): make the next process-environment read fail the build	#1843

[mergify]

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[sileht]

Revision history

#	Type	Changes	Reason	Date
1	initial	7c98c5e		2026-09-18 07:38 UTC
2	content	7c98c5e → 7d63c95		2026-09-18 07:38 UTC
3	content	7d63c95 → 083b61b		2026-09-18 08:13 UTC
4	rebase	083b61b → befb4f4 (rebase only)		2026-09-21 05:43 UTC

[Copilot]

🟡 Changes recommended

Two review comments remain regarding documentation and regression-test coverage.

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Pull request overview

Refactors CLI environment handling through mergify_core::env, removes environment-mutating tests, and treats empty MERGIFY_BASE_URL as unset.

Changes:

• Adds Clap command-tree and parsing assertions.
• Updates environment access in CLI and self-update code.
• Removes the unused temp-env dependency.

File summaries

File	Summary
crates/mergify-cli/src/self_update.rs	Handles empty base URLs; add focused regression tests.
crates/mergify-cli/src/main.rs	Updates environment access and Clap tests; refresh the stale deleted-test reference.
crates/mergify-cli/Cargo.toml	Removes temp-env.
Cargo.lock	Updates dependency metadata.

Review details

• Files reviewed: 3/4 changed files
• Comments generated: 2
• Review effort level: Lite

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[mergify]

@sileht this pull request is now in conflict 😩

Pull request has been modified.

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-09-21 08:21 UTC · Rule: default · triggered by merge protections
• ✅ Checks skipped · PR is already up-to-date
• ✅ Merged — 2026-09-21 08:21 UTC · at c50a1cc7365989ce9f57d81ae23722b34f01aca2 · squash

This pull request spent 20 seconds in the queue, including 2 seconds running CI.

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