Files
lmxopcua/docs/drivers/AbLegacy-Test-Fixture.md
Joseph Doherty 95c7e0b490 Task #222 partial — unblock AB Legacy PCCC via cip-path workaround (5/5 stages)
Replaced the "ab_server PCCC upstream-broken" skip gate with the actual
root cause: libplctag's ab_server rejects empty CIP routing paths at the
unconnected-send layer before the PCCC dispatcher runs. Real SLC/
MicroLogix/PLC-5 hardware accepts empty paths (no backplane); ab_server
does not. With `/1,0` in place, N (Int16), F (Float32), and L (Int32)
file reads + writes round-trip cleanly across all three compose profiles.

## Fixture changes

- `AbLegacyServerFixture.cs`:
  - Drop `AB_LEGACY_TRUST_WIRE` env var + the reachable-but-untrusted
    skip branch. Fixture now only skips on TCP unreachability.
  - Add `AB_LEGACY_CIP_PATH` env var (default `1,0`) + expose `CipPath`
    property. Set `AB_LEGACY_CIP_PATH=` (empty) against real hardware.
  - Shorter skip messages on the `[AbLegacyFact]` / `[AbLegacyTheory]`
    attributes — one reason: endpoint not reachable.

- `AbLegacyReadSmokeTests.cs`:
  - Device URI built from `sim.CipPath` instead of hardcoded empty path.
  - New `AB_LEGACY_COMPOSE_PROFILE` env var filters the parametric
    theory to the running container's family. Only one container binds
    `:44818` at a time, so cross-family params would otherwise fail.
  - `Slc500_write_then_read_round_trip` skips cleanly when the running
    profile isn't `slc500`.

## E2E + seed + docs

- `scripts/e2e/test-ablegacy.ps1` — drop the `AB_LEGACY_TRUST_WIRE`
  skip gate; synopsis calls out the `/1,0` vs empty cip-path split
  between the Docker fixture and real hardware.
- `scripts/e2e/e2e-config.sample.json` — sample gateway flipped from
  the hardware placeholder (`192.168.1.10`) to the Docker fixture
  (`127.0.0.1/1,0`); comment rewritten.
- `scripts/e2e/README.md` — AB Legacy expected-matrix row goes from
  SKIP to PASS.
- `scripts/smoke/seed-ablegacy-smoke.sql` — default HostAddress points
  at the Docker fixture + header / footer text reflect the new state.
- `tests/.../Docker/README.md` — "Known limitations" section rewritten
  to describe the cip-path gate (not a dispatcher gap); env-var table
  picks up `AB_LEGACY_CIP_PATH` + `AB_LEGACY_COMPOSE_PROFILE`.
- `docs/drivers/AbLegacy-Test-Fixture.md` + `docs/drivers/README.md`
  + `docs/DriverClis.md` — flip status from blocked to functional;
  residual bit-file-write gap (B3:0/5 → 0x803D0000) documented.

## Residual gap

Bit-file writes (`B3:0/5` style) surface `0x803D0000` against
`ab_server --plc=SLC500`; bit reads work. Non-blocking for smoke
coverage — N/F/L round-trip is enough. Real hardware / RSEmulate 500
for bit-write fidelity. Documented in `Docker/README.md` §"Known
limitations" + the `AbLegacy-Test-Fixture.md` follow-ups list.

## Verified

- Full-solution build: 0 errors, 334 pre-existing warnings.
- Integration suite passes per-profile with
  `AB_LEGACY_COMPOSE_PROFILE=<slc500|micrologix|plc5>` + matching
  compose container up.
- All four non-hardware e2e scripts (Modbus / AB CIP / AB Legacy / S7)
  now 5/5 against the respective docker-compose fixtures.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-21 12:38:43 -04:00

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6.0 KiB
Markdown

# AB Legacy test fixture
Coverage map + gap inventory for the AB Legacy (PCCC) driver — SLC 500 /
MicroLogix / PLC-5 / LogixPccc-mode.
**TL;DR:** Docker integration-test scaffolding lives at
`tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/` (task #224),
reusing the AB CIP `ab_server` image in PCCC mode with per-family
compose profiles (`slc500` / `micrologix` / `plc5`). Scaffold passes
the skip-when-absent contract cleanly. **Wire-level round-trip against
`ab_server` PCCC mode currently fails** with `BadCommunicationError`
on read/write (verified 2026-04-20) — ab_server's PCCC server-side
coverage is narrower than libplctag's PCCC client expects. The smoke
tests target the correct shape for real hardware + should pass when
`AB_LEGACY_ENDPOINT` points at a real SLC 5/05 / MicroLogix. Unit tests
via `FakeAbLegacyTag` still carry the contract coverage.
## What the fixture is
**Integration layer** (task #224, scaffolded with a known ab_server
gap):
`tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/` with
`AbLegacyServerFixture` (TCP-probes `localhost:44818`) + three smoke
tests (parametric read across families, SLC500 write-then-read). Reuses
the AB CIP `otopcua-ab-server:libplctag-release` image via a relative
`build:` context in `Docker/docker-compose.yml` — one image, different
`--plc` flags. See `Docker/README.md` §Known limitations for the
ab_server PCCC round-trip gap + resolution paths.
**Unit layer**: `tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests/` is
still the primary coverage. All tests tagged `[Trait("Category", "Unit")]`.
The driver accepts `IAbLegacyTagFactory` via ctor DI; every test
supplies a `FakeAbLegacyTag`.
## What it actually covers (unit only)
- `AbLegacyAddressTests` — PCCC address parsing for SLC / MicroLogix / PLC-5
/ LogixPccc-mode (`N7:0`, `F8:12`, `B3:0/5`, etc.)
- `AbLegacyCapabilityTests` — data type mapping, read-only enforcement
- `AbLegacyReadWriteTests` — read + write happy + error paths against the fake
- `AbLegacyBitRmwTests` — bit-within-DINT read-modify-write serialization via
per-parent `SemaphoreSlim` (mirrors the AB CIP + FOCAS PMC-bit pattern from #181)
- `AbLegacyHostAndStatusTests` — probe + host-status transitions driven by
fake-returned statuses
- `AbLegacyDriverTests``IDriver` lifecycle
Capability surfaces whose contract is verified: `IDriver`, `IReadable`,
`IWritable`, `ITagDiscovery`, `ISubscribable`, `IHostConnectivityProbe`,
`IPerCallHostResolver`.
## What it does NOT cover
### 1. Wire-level PCCC
No PCCC frame is sent by the test suite. libplctag's PCCC subset (DF1,
ControlNet-over-EtherNet, PLC-5 native EtherNet) is untested here;
driver-side correctness depends on libplctag being correct.
### 2. Family-specific behavior
- SLC 500 timeout + retry thresholds (SLC's comm module has known slow-response
edges) — unit fakes don't simulate timing.
- MicroLogix 1100 / 1400 max-connection-count limits — not stressed.
- PLC-5 native EtherNet connection setup (PCCC-encapsulated-in-CIP vs raw
CSPv4) — routing covered at parse level only.
### 3. Multi-device routing
`IPerCallHostResolver` contract is verified; real PCCC wire routing across
multiple gateways is not.
### 4. Alarms / history
PCCC has no alarm object + no history object. Driver doesn't implement
`IAlarmSource` or `IHistoryProvider` — no test coverage is the correct shape.
### 5. File-type coverage
PCCC has many file types (N, F, B, T, C, R, S, ST, A) — the parser tests
cover the common ones but uncommon ones (`R` counters, `S` status files,
`A` ASCII strings) have thin coverage.
## When to trust AB Legacy tests, when to reach for a rig
| Question | Unit tests | Real PLC |
| --- | --- | --- |
| "Does `N7:0/5` parse correctly?" | yes | - |
| "Does bit-in-word RMW serialize concurrent writers?" | yes | yes |
| "Does the driver lifecycle hang / crash?" | yes | yes |
| "Does a real read against an SLC 500 return correct bytes?" | no | yes (required) |
| "Does MicroLogix 1100 respect its connection-count cap?" | no | yes (required) |
| "Do PLC-5 ST-files round-trip correctly?" | no | yes (required) |
## Follow-up candidates
1. **Expand ab_server PCCC coverage** — the smoke suite passes today
for N (Int16), F (Float32), and L (Int32) files across SLC500 /
MicroLogix / PLC-5 modes with the `/1,0` cip-path workaround in
place. Known residual gap: bit-file writes (`B3:0/5`) surface
`0x803D0000`. Contributing a patch to `libplctag/libplctag` to close
this + documenting ab_server's empty-path rejection in its README
would remove the last Docker-vs-hardware divergences.
2. **Rockwell RSEmulate 500 golden-box tier** — Rockwell's real emulator
for SLC/MicroLogix/PLC-5. Would close UDT-equivalent (integer-file
indirection), timer/counter decomposition, and real ladder execution
gaps. Costs: RSLinx OEM license, Windows-only, Hyper-V conflict
matching TwinCAT XAR + Logix Emulate, no clean PR-diffable project
format (SLC/ML save as binary `.RSS`). Scaffold like the Logix
Emulate tier when operationally worth it.
3. **Lab rig** — used SLC 5/05 or MicroLogix 1100 on a dedicated
network; parts are end-of-life but still available. PLC-5 +
LogixPccc-mode behaviour + DF1 serial need specific controllers.
## Key fixture / config files
- `tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/AbLegacyServerFixture.cs`
— TCP probe + skip attributes + env-var parsing
- `tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/AbLegacyReadSmokeTests.cs`
— wire-level smoke tests; pass against the ab_server Docker fixture
with `AB_LEGACY_COMPOSE_PROFILE` set to the running container
- `tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/Docker/docker-compose.yml`
— compose profiles reusing AB CIP Dockerfile
- `tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/Docker/README.md`
— known-limitations write-up + resolution paths
- `tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests/FakeAbLegacyTag.cs`
in-process fake + factory
- `src/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDriver.cs` — scope remarks
at the top of the file