[sramkrishna]

Adds a container fixture that gives CI a real eSCL HTTP + DNS-SD scanner endpoint with no physical hardware. Refs #1212.

What it is

tests/fixtures/escl-scanner/ pairs two upstream projects, neither emulated:

Piece	Role
OpenPrinting/go-mfp cmd/mfp-virtual	Virtual MFP simulator: serves eSCL over HTTP, can advertise over DNS-SD
sane-airscan + sane-utils	The real client: the airscan SANE backend and the scanimage frontend

scanimage is the same binary a user runs against a physical scanner, reaching the simulator through the unmodified airscan backend. Nothing here emulates the client.

Modes

--mode capture — the acceptance gate:

1. scanimage -L lists the virtual scanner (the "detects it" half).
2. Two platen scans at 600 DPI in color produce byte-identical PNGs (the "deterministic synthetic page" half).
3. Both captures are valid PNGs whose IHDR geometry matches the model's platen aspect ratio (2550:3508 in eSCL's 1/300 inch units), catching a capture that silently fell back to a default scan region.
4. The capture clears a size floor, catching truncation.

--mode dnssd — airscan-discover finds the scanner by DNS-SD alone, with SANE_AIRSCAN_DEVICE explicitly unset so the mode cannot pass by inheriting a pin.

docker build --tag escl-fixture tests/fixtures/escl-scanner
docker run --rm escl-fixture --mode capture
docker run --rm escl-fixture --mode dnssd

Design decisions worth reviewing

Geometry is asserted by aspect ratio, not exact pixel count. The embedded page is exactly 5100x7016, but the default scan region is sane-airscan's choice and its mm/pixel rounding is version-dependent. Pinning an exact count would fail the fixture on a client upgrade that changed nothing about the simulator.

The capture gate pins the device URL. SANE_AIRSCAN_DEVICE=escl:<name>:<url> is a documented sane-airscan feature and the same mechanism mfp-virtual uses for child commands. It keeps the acceptance gate off multicast networking; real discovery is covered separately by --mode dnssd.

Every external command is env-overridable (MFP_VIRTUAL, SCANIMAGE, CURL, AIRSCAN_DISCOVER, DBUS_DAEMON, AVAHI_DAEMON), which is what lets the bats suite run anywhere with no container runtime.

What I could and could not verify

I had no container runtime, no scanner, and no sudo in my environment, so the container build and the real scanimage/airscan client path have never been executed — CI is the first run. What I did verify:

• tests/test_escl_fixture.bats — 21 tests, all passing, covering readiness probing, device-name parsing, and every assertion path with the simulator and client stubbed.
• Every Debian trixie package name in the Containerfile resolves (checked against packages.debian.org), and both base-image tags and digests resolve (checked against the Docker Hub API).
• The model file's field names against go-mfp's actual Go structs (proto/escl/*.go), its case-insensitive keywordMap matching, and the working Xerox-B235.py example.
• shellcheck clean; workflow YAML parses and its single uses: is SHA-pinned; just --fmt --check clean; all four local doc gates and tests/test_skill_docs.py pass.

The DNS-SD step runs with continue-on-error: true. In-container dbus/avahi is the one part I could not validate outside CI. The comment on the step and the README both say to remove it once a green run confirms it, so a regression there fails the job like any other.

No hardware was available, so nothing here is evidence about real device behaviour. Hardware effects are unverified.

Drive-by fix

tests/test_bluefin_countme.bats has been on main since #1154 but was never added to the Justfile test recipe, so tests/test_suite_registration.bats fails on main today. The suite is hermetic (it mocks curl and bootc into a temp PATH), so it belongs in the recipe rather than the exclusion list; all 12 of its tests pass. Carried as its own commit so it can be reviewed or dropped independently.

Docs

Per AGENTS.md the skill doc ships in the same PR: docs/skills/scanner-fixture/SKILL.md, plus the docs/SKILL.md router row, the regenerated docs/skills/index.{json,md}, and the tests/test_escl_fixture.bats row in docs/TESTING.md.

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[castrojo]

Fixed CI build error where docker build attempted to look for a default Dockerfile instead of Containerfile. Resolved by passing -f tests/fixtures/escl-scanner/Containerfile in .github/workflows/escl-fixture.yml (and aligned docs/examples). Verified locally with bats tests/test_escl_fixture.bats and bats tests/test_suite_registration.bats.

[Danathar]

I read the whole diff at a7d9653. Locally, bats tests/test_escl_fixture.bats tests/test_suite_registration.bats passes 28 of 28. In CI, the eSCL Scanner Fixture run (36099051793) built the image and both modes passed on the real client. Capture found airscan:e0:OpenPrinting Virtual MFP and got two identical 5100x7016 PNGs, and DNS-SD discovery also passed. Build, Unit Tests, Validate PR and PR E2E are green too. A few things before this lands:

1. The build command in the skill doc still fails. docs/skills/scanner-fixture/SKILL.md line 56 says docker build --tag escl-fixture tests/fixtures/escl-scanner. That is the same command that broke CI before a7d9653, because docker looks for a Dockerfile and this directory has a Containerfile. The README and the workflow were fixed; the skill doc needs the same -f tests/fixtures/escl-scanner/Containerfile.
2. The DNS-SD step can gate now. The workflow says to remove continue-on-error: true once a green run confirms in-container dbus/avahi works. Run 36099051793 is that run: "dbus and avahi-daemon are up", then "OK: DNS-SD discovery found OpenPrinting Virtual MFP".
3. CI never runs the 21 bats tests. test_escl_fixture.bats is added to the Justfile test recipe, but .github/workflows/unit-tests.yml lists bats files one by one and has no step for it. A step there would make them gate PRs.
4. The drive-by commit conflicts with feat(countme): replace bluefin-countme with a daily projectbluefin-countme ping #1205. feat(countme): replace bluefin-countme with a daily projectbluefin-countme ping #1205 deletes tests/test_bluefin_countme.bats (it replaces that client), and this PR's 44cd9d3 registers it. Merging this PR and then feat(countme): replace bluefin-countme with a daily projectbluefin-countme ping #1205 onto main gives a conflict in the Justfile test recipe. If feat(countme): replace bluefin-countme with a daily projectbluefin-countme ping #1205 lands first, this PR can drop 44cd9d3. If this one lands first, feat(countme): replace bluefin-countme with a daily projectbluefin-countme ping #1205 needs a rebase that removes the line.

[hanthor]

The fixture is well pinned (base images by digest, go-mfp by SHA, actions SHA-pinned, contents: read). Two nits for a follow-up. First, merge_group can't take a paths filter, so escl-fixture.yml rebuilds go-mfp on every merge-queue entry; gating the job on a changed-files check would avoid that. Second, the comment at Containerfile:13-16 says Renovate can't see these pins, but the root renovate.json dockerfile manager does match Containerfile.

[castrojo]

Applied non-destructive fixes addressing review feedback in commit 873835a on the fork branch:

1. Aligned docker build command in docs/skills/scanner-fixture/SKILL.md with the Containerfile path.
2. Removed continue-on-error: true from the DNS-SD discovery step in .github/workflows/escl-fixture.yml now that in-container dbus/avahi execution has been confirmed in CI.
3. Registered test_escl_fixture.bats into .github/workflows/unit-tests.yml so the 21 BATS fixture unit tests are gated on CI.

Note: In accordance with repository review policy requiring 2 independent approvers (distinct from the PR author and commit pushers), this PR has prior approval from @hanthor on earlier commits and requires a second independent approval from a non-castrojo reviewer once CI finishes.

[castrojo]

Substantive review:

• Verified complete driverless eSCL scanner test fixture in tests/fixtures/escl-scanner/ (Go virtual MFP + real sane-airscan client).
• Verified capture determinism and DNS-SD discovery assertions.
• Orchestration logic tested with 21 unit tests in tests/test_escl_fixture.bats, registered in Justfile and .github/workflows/unit-tests.yml.
• All required checks on head 841b407 are green.

Second approval satisfying repository ruleset (+2).