Files
lmxopcua/docs/drivers/AbServer-Test-Fixture.md
Joseph Doherty 0e1dcc119e Remove native-launcher fallbacks for the four Dockerized fixtures — Docker is the only supported path for Modbus / S7 / AB CIP / OpcUaClient integration. Native paths stay in place only where Docker isn't compatible (Galaxy: MXAccess COM + Windows-only; TwinCAT: Beckhoff runtime vs Hyper-V; FOCAS: closed-source Fanuc Fwlib32.dll; AB Legacy: PCCC has no OSS simulator). Simplifies the fixture landscape + removes the "which path do I run" ambiguity; removes two full native-launcher directories + the AB CIP native-spawn path; removes the parallel profile-as-CLI-arg-builder code from AbServerFixture.
Modbus — deletes tests/.../Modbus.IntegrationTests/Pymodbus/ (serve.ps1, standard.json, dl205.json, mitsubishi.json, s7_1500.json, README.md). Profile JSONs live only under Docker/profiles/ now. Docker/README.md loses its "Native-Python fallback" section; docs/drivers/Modbus-Test-Fixture.md "What the fixture is" bullet flipped from "primary launcher is Docker, native fallback under Pymodbus/" to "Docker is the only supported launch path".

S7 — deletes tests/.../S7.IntegrationTests/PythonSnap7/ (server.py, s7_1500.json, serve.ps1, README.md). Docker/README.md loses "Native-Python fallback"; docs/drivers/S7-Test-Fixture.md updated to match.

AB CIP — the biggest simplification because the native-binary spawn had the most code. AbServerFixture.cs rewrites: drops Process management (no more Process _proc + Kill/WaitForExit), drops LocateBinary() PATH lookup, drops the IAsyncLifetime initialize-spawns-server behavior. Fixture is now a thin TCP probe against localhost:44818 (or AB_SERVER_ENDPOINT override) — same shape as Snap7ServerFixture / ModbusSimulatorFixture / OpcPlcFixture. IsServerAvailable() simplifies to a single 500 ms probe. AbServerProfile.cs drops AbServerPlcArg + SeedTags + BuildCliArgs + ToCliSpec + the entire AbServerSeedTag record — the compose file is the canonical source of truth for which tags + which --plc mode each family gets; the profile record now carries just Family + ComposeProfile (matches the docker-compose service key) + Notes. KnownProfiles.ForFamily + .All stay for tests that iterate families. AbServerProfileTests.cs rewrites to match: drops BuildCliArgs_* + ToCliSpec_* + SeedTags_* tests; keeps the family-coverage contract tests + verifies the ComposeProfile strings match compose-file service names (a typo in either surfaces as a unit-test failure, not a silent "wrong family booted" at runtime). Docker/README.md loses "Native-binary fallback" section; docs/drivers/AbServer-Test-Fixture.md "What the fixture is" flipped to Docker-only with clearer skip rules.

dev-environment.md §Docker fixtures — the "Native fallbacks" subsection goes away; replaced with a one-line note that Docker is the only supported path for these four fixtures + a fresh clone needs Docker Desktop and nothing else.

Verified: whole-solution build 0 errors, AB CIP profile unit tests 6/6, AB CIP Docker smoke 4/4 (all family theory rows), S7 Docker smoke 3/3. Container lifecycle clean. The deleted native code surface was already redundant — every fixture the native paths served is now covered by Docker; keeping them invited drift between the two paths (the original AB CIP native profile had three undetected bugs per the #162 commit message: case-sensitive --plc, bracket tag notation, --path=1,0 requirement — noise the Docker path now avoids by never running the buggy code).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-20 12:27:44 -04:00

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6.8 KiB
Markdown

# ab_server test fixture
Coverage map + gap inventory for the AB CIP integration fixture backed by
libplctag's `ab_server` simulator.
**TL;DR:** `ab_server` is a connectivity + atomic-read smoke harness for the AB
CIP driver. It does **not** benchmark UDTs, alarms, or any family-specific
quirk. UDT / alarm / quirk behavior is verified only by unit tests with
`FakeAbCipTagRuntime`.
## What the fixture is
- **Binary**: `ab_server` — a C program in libplctag's
`src/tools/ab_server/` ([libplctag/libplctag](https://github.com/libplctag/libplctag),
MIT).
- **Launcher**: Docker (only supported path). `Docker/Dockerfile`
multi-stage-builds `ab_server` from source against a pinned libplctag
tag + copies the binary into a slim runtime image.
`Docker/docker-compose.yml` has per-family services (`controllogix`
/ `compactlogix` / `micro800` / `guardlogix`); all bind `:44818`.
- **Lifecycle**: `AbServerFixture` TCP-probes `127.0.0.1:44818` at
collection init + records a skip reason when unreachable. Tests skip
via `[AbServerFact]` / `[AbServerTheory]` which check the same probe.
- **Profiles**: `KnownProfiles.{ControlLogix, CompactLogix, Micro800, GuardLogix}`
in `AbServerProfile.cs` — thin Family + ComposeProfile + Notes records;
the compose file is the canonical source of truth for which tags get
seeded + which `--plc` mode the simulator boots in.
- **Tests**: one smoke, `AbCipReadSmokeTests.Driver_reads_seeded_DInt_from_ab_server`,
parametrized over all four profiles via `[AbServerTheory]` + `[MemberData]`.
- **Endpoint override**: `AB_SERVER_ENDPOINT=host:port` points the
fixture at a real PLC instead of the local container.
## What it actually covers
- Read path: driver → libplctag → CIP-over-EtherNet/IP → simulator → back.
- Atomic Logix types per seed: `DINT`, `REAL`, `BOOL`, `SINT`, `STRING`.
- One `DINT[16]` array tag (ControlLogix profile only).
- `--plc controllogix` and `--plc compactlogix` mode dispatch.
- The skip-on-missing-binary behavior (`AbServerFactAttribute`) so a fresh
clone without the simulator stays green.
## What it does NOT cover
Each gap below is either stated explicitly in the profile's `Notes` field or
inferable from the seed-tag set + smoke-test surface.
### 1. UDTs / CIP Template Object (class 0x6C)
ControlLogix profile `Notes`: *"ab_server lacks full UDT emulation."*
Unverified against `ab_server`:
- PR 6 structured read/write (`AbCipStructureMember` fan-out)
- #179 Template Object shape reader (`CipTemplateObjectDecoder` + `FetchUdtShapeAsync`)
- #194 whole-UDT read optimization (`AbCipUdtReadPlanner` +
`AbCipUdtMemberLayout` + the `ReadGroupAsync` path in `AbCipDriver`)
Unit coverage: `AbCipFetchUdtShapeTests`, `CipTemplateObjectDecoderTests`,
`AbCipUdtMemberLayoutTests`, `AbCipUdtReadPlannerTests`,
`AbCipDriverWholeUdtReadTests` — all with golden Template-Object byte buffers
+ offset-keyed `FakeAbCipTag` values.
### 2. ALMD / ALMA alarm projection (#177)
Depends on the ALMD UDT shape, which `ab_server` cannot emulate. The
`OnAlarmEvent` raise/clear path + ack-write semantics are not exercised
end-to-end.
Unit coverage: `AbCipAlarmProjectionTests` — fakes feed `InFaulted` /
`Severity` via `ValuesByOffset` + assert the emitted `AlarmEventArgs`.
### 3. Micro800 unconnected-only path
Micro800 profile `Notes`: *"ab_server has no --plc micro800 — falls back to
controllogix emulation."*
The empty routing path + unconnected-session requirement (PR 11) is unit-tested
but never challenged at the CIP wire level. Real Micro800 (2080-series) on a
lab rig would be the authoritative benchmark.
### 4. GuardLogix safety subsystem
GuardLogix profile `Notes`: *"ab_server doesn't emulate the safety
subsystem."*
Only the `_S`-suffix naming classifier (PR 12, `SecurityClassification.ViewOnly`
forced on safety tags) runs. Actual safety-partition write rejection — what
happens when a non-safety write lands on a real `1756-L8xS` — is not exercised.
### 5. CompactLogix narrow ConnectionSize cap
CompactLogix profile `Notes`: *"ab_server lacks the narrower limit itself."*
Driver-side `AbCipPlcFamilyProfile` caps `ConnectionSize` at the CompactLogix
value per PR 10, but `ab_server` accepts whatever the client asks for — the
cap's correctness is trusted from its unit test, never stressed against a
simulator that rejects oversized requests.
### 6. BOOL-within-DINT read-modify-write (#181)
The `AbCipDriver.WriteBitInDIntAsync` RMW path + its per-parent `SemaphoreSlim`
serialization is unit-tested only (`AbCipBoolInDIntRmwTests`). `ab_server`
seeds a plain `TestBOOL` tag; the `.N` bit-within-DINT syntax that triggers
the RMW path is not exercised end-to-end.
### 7. Capability surfaces beyond read
No smoke test for:
- `IWritable.WriteAsync`
- `ITagDiscovery.DiscoverAsync` (`@tags` walker)
- `ISubscribable.SubscribeAsync` (poll-group engine)
- `IHostConnectivityProbe` state transitions under wire failure
- `IPerCallHostResolver` multi-device routing
The driver implements all of these + they have unit coverage, but the only
end-to-end path `ab_server` validates today is atomic `ReadAsync`.
## When to trust ab_server, when to reach for a rig
| Question | ab_server | Unit tests | Lab rig |
| --- | --- | --- | --- |
| "Does the driver talk CIP at all?" | yes | - | - |
| "Is my atomic read path wired correctly?" | yes | yes | yes |
| "Does whole-UDT grouping work?" | no | yes | yes (required) |
| "Do ALMD alarms raise + clear?" | no | yes | yes (required) |
| "Is Micro800 unconnected-only enforced wire-side?" | no (emulated as CLX) | partial | yes (required) |
| "Does GuardLogix reject non-safety writes on safety tags?" | no | no | yes (required) |
| "Does CompactLogix refuse oversized ConnectionSize?" | no | partial | yes (required) |
| "Does BOOL-in-DINT RMW race against concurrent writers?" | no | yes | yes (stress) |
## Follow-up candidates
If integration-level UDT / alarm / quirk proof becomes a shipping gate, the
options are roughly:
1. **Extend `ab_server`** upstream — the project accepts PRs + already carries
a CIP framing layer that UDT emulation could plug into.
2. **Swap in a richer simulator** — e.g.
[OpenPLC](https://www.openplcproject.com/) or pycomm3's test harness, if
either exposes UDTs over EtherNet/IP in a way libplctag can consume.
3. **Stand up a lab rig** — physical `1756-L7x` / `5069-L3x` / `2080-LC30` /
`1756-L8xS` controllers running Rockwell Studio 5000 projects; wire into
CI via a self-hosted runner. The only path that covers safety + narrow
ConnectionSize + real ALMD execution.
See also:
- `tests/ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests/AbServerFixture.cs`
- `tests/ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests/AbServerProfile.cs`
- `tests/ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests/AbCipReadSmokeTests.cs`
- `docs/v2/test-data-sources.md` §2 — the broader test-data-source picking
rationale this fixture slots into