test: retain process.env when overriding NETLIFY vars

[43081j]

The previous code was nuking the entire process.env which meant some built-in tools like os.tmpdir() would be undefined on Windows (as it depends on env.TEMP or some such thing existing).

We should be able to safely extend the existing env instead of overwriting it.

I suspect this will fix:
https://github.com/netlify/cli/actions/runs/31727425876/job/94549735809#step:10:286

Since that error happens when joining an undefined tmpdir.

---

For us to review and ship your PR efficiently, please perform the following steps:

• Open a bug/issue before writing your code 🧑‍💻. This ensures we
  can discuss the changes and get feedback from everyone that should be involved. If you`re fixing a typo or
  something that`s on fire 🔥 (e.g. incident related), you can skip this step.
• Read the contribution guidelines 📖. This ensures your code follows our style guide and
  passes our tests.
• Update or add tests (if any source code was changed or added) 🧪
• Update or add documentation (if features were changed or added) 📝
• Make sure the status checks below are successful ✅

A picture of a cute animal (not mandatory, but encouraged)

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 3a9503e1-d57d-4244-84ce-05505f6cc6f1

📥 Commits

Reviewing files that changed from the base of the PR and between 66797b6 and ae9b63e.

📒 Files selected for processing (1)

• tests/integration/commands/build/build-program.test.ts

🔗 Linked repositories identified

CodeRabbit considers these linked repositories for cross-repo context during reviews:

• netlify/blueprints (manual)

---

📝 Walkthrough

Summary by CodeRabbit

• Tests

  • Improved build validation to retain existing environment settings while applying test-specific API configuration.
  • This strengthens test reliability and reduces the risk of environment-related inconsistencies during build verification.

• User Impact

  • No direct user-facing changes are included in this update.

Walkthrough

The build integration test now merges the original process environment with mock API variables before running the build. It no longer replaces the complete environment.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Mergeability Score: ⚪ Minimal · up to ae9b6

This is a localized test-only change with no actionable merge-blocking risk remaining after normal checks and review.

Suggested reviewers: amun-sihra

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly identifies the test change that retains process.env while overriding NETLIFY variables.
Description check	✅ Passed	The description explains the process.env issue, its Windows impact, and the test change that addresses it.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/netlify-cli@8412

commit: ae9b63e

[serhalp]

🙏🏼 thank you!