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