[quality] test: unit coverage for scripts/compose-e2e-image.sh (new tests/unit/test_compose_e2e_image.py)

[kubestellar-hive]

Test Improvement

Adds tests/unit/test_compose_e2e_image.py — 18 behavioural tests for scripts/compose-e2e-image.sh, which previously had zero coverage.

Claimed ground (for open-PR disjointness checks)

• Adds: tests/unit/test_compose_e2e_image.py (new file, only file in the diff)
• Covers: scripts/compose-e2e-image.sh only
• Touches no production code, no shared module, no other test file.

Disjoint from every open testsuite PR: #766 (generate_skill_index.py, update_coverage_snapshot.py), #768 (offline_boot_steps.py, sudo_rs_steps.py, bctl_steps.py, update_failure_steps.py), #765 (environment.py quarantine contract), #773 (SSH transport / ssh_config.py), #771 (Containerfile.runner), #751 (screenshot_steps.py), #757 (input-remapper QEMU).

Why this script matters

compose-e2e-image.sh builds the E2E overlay layer FROM the image under test and pushes the composed ref that every suite job boots. It runs only inside e2e.yml, so a regression in it surfaces as a red E2E lane that reads like a product regression rather than a tooling bug.

What is asserted

The script is executed in a hermetic sandbox (fake podman/sudo shims on PATH, throwaway E2E_OVERLAY_DIR, no registry contact), and assertions are on observed argv/exit codes rather than source text:

• argument-count guards exit 2 without invoking podman
• a missing overlay Containerfile exits 1 before any build
• --build-arg carries the base ref; -t carries the composed ref
• -f and the build context both resolve to the overlay directory
• build strictly precedes push; a failed build never reaches the registry
• a failed push is not swallowed into a success
• the composed ref is the final stdout line e2e.yml consumes
• the PODMAN default expands as words to sudo podman (root image store)
• refs containing shell metacharacters pass through unexpanded

Verification

python3 -m pytest tests/unit/test_compose_e2e_image.py -q   # 18 passed

Mutation-checked — each of these breaks at least one test: self-referential BASE_IMAGE, dropping set -e, removing the final echo, dropping sudo from the PODMAN default, loosening $# -ne 2.

Full tests/unit/ run is unchanged apart from the new file (pre-existing failures/errors in this environment come from missing behave/selenium, untouched by this PR).

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Filed by quality agent (hold-gated mode). Human review required — do not merge automatically.

— hive: agent=quality backend=copilot model=claude-opus-5

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 99.39024% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
tests/unit/test_compose_e2e_image.py	99.39%	1 Missing ⚠️

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