tests: Port test-switch-zstd-chunked to Rust

[andrewdunndev]

First port for #2547. test-switch-zstd-chunked.nu becomes bootc-integration-tests booted switch-zstd-chunked, and its tmt entry runs that instead of nu. I picked it because it builds an image on the target, pushes it, switches to it and reboots, so it brings over pieces many other tests share: TAP output, dispatch on TMT_REBOOT_COUNT, bootc status --json and the UKI Containerfile helper from tap.nu.

Ported tests are modules under a new booted subcommand in tests-integration. The bootc-tests subpackage already installs that binary in the test image, so packaging doesn't change. Your issue suggests a separate bootc-tests binary; would you rather have that?

cargo xtask update-generated now also reads the number/tmt/extra header from // comments in crates/tests-integration/src/booted/*.rs, so plan-50 keeps its name, summary, duration and skip_if_ostree (for #2402). Every failure exits 1, which tmt reports as a failure: checks return errors instead of panicking (a panic's 101 is a tmt error), and a failing command no longer passes its own exit code through as nushell did (podman's 125 was a tmt error).

Packit

Packit, and gating runs using the same prepare steps, boot an image built from Containerfile.packit, which doesn't install bootc-tests, and Packit's Copr build doesn't pass --with tests. So the plan is now disabled outside running_env=image_mode, with the same rule as test-27. Only cargo xtask run-tmt applies skip_if_ostree, so today plan-50 runs and passes on Packit's ostree images (all four tier-1 targets on #2314); this drops those runs, and gating's, until bootc-tests is built there. Every later port hits the same gap, so I'd look at getting bootc-tests into the Packit image next.

flowchart TD
    header["header comments in booted/switch_zstd_chunked.rs"] -->|cargo xtask update-generated| plan["plan-50 runs<br/>bootc-integration-tests booted switch-zstd-chunked"]
    plan --> env{running_env}
    env -->|image_mode| bcvk["run-tmt boots the Dockerfile image,<br/>which installs bootc-tests"]
    env -->|Packit and gating| off["plan disabled:<br/>Containerfile.packit has no bootc-tests"]

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Testing

In a Fedora 44 container, make validate, cargo xtask update-generated direct --check and the tests-integration and xtask unit tests pass. With bootc, podman, skopeo and tmt-reboot stubbed out, the port and the nushell original print the same TAP lines on both boots and when each check fails, pass and fail in the same cases, and generate the same UKI stages. In a test VM, just test-tmt switch-zstd-chunked passes on composefs BLS and unsealed UKI.

[cgwalters]

Neat! Thanks for starting the ball rolling on this. I personally think this looks nicer indeed.

[cgwalters]

Actually though what we want to do is create e.g. bootc-tests.rpm or so.

[cgwalters]

I think this is ok for now but as a followup since we're porting anyways let's require some structured metadata here. I think YAML frontmatter would be appropriate, we could perhaps extract that from rustdoc and avoid parsing rust code on our own?

Or just require

// # tmt-begin
...
/// # tmt-end

or so?