Add a test for nix ps

[edolstra]

Motivation

Context

Summary by CodeRabbit

Release Notes

• Tests
  • Added functional tests for the nix ps command to validate reporting of running derivations and their associated process information in both standard and JSON output formats.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: be7a27b2-1983-418c-9e37-9e4c8cd11a15

📥 Commits

Reviewing files that changed from the base of the PR and between ec9440d and 95aad5b.

📒 Files selected for processing (2)

• tests/functional/meson.build
• tests/functional/ps.sh

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📝 Walkthrough

Walkthrough

This pull request adds a new functional test for the nix ps command. The test script validates both plain and JSON output formats when a derivation is running, then confirms the command returns empty results after the build completes. The test is registered in the Meson build system to ensure it runs as part of the functional test suite.

Changes

nix ps functional test

Layer / File(s)	Summary
nix ps functional test implementation tests/functional/ps.sh	Bash test script that coordinates a blocked Nix build via FIFOs, asserts nix ps reports the running derivation with correct process argv and JSON structure, then unblocks the build and verifies empty output afterward.
Register ps.sh in build system tests/functional/meson.build	Adds the ps.sh script to the main test suite's tests array for Meson integration.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 A test hops into the night,
Watching processes in their flight,
FIFOs block and then release,
JSON fields bring the peace,
Nix ps now shines so bright!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Add a test for nix ps' directly and clearly describes the main changes in the pull request, which adds a new functional test script for the nix ps command.
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.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch nix-ps-test

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[github-actions]

🚀 Deployed on https://6a21cff56df3d9e9f9378203--determinate-nix.netlify.app