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S7 integration — AbCip/Modbus already have real-simulator integration suites; S7 had zero wire-level coverage despite being a Tier-A driver (all unit tests mocked IS7Client). Picked python-snap7's `snap7.server.Server` over raw Snap7 C library because `pip install` beats per-OS binary-pin maintenance, the package ships a Python __main__ shim that mirrors our existing pymodbus serve.ps1 + *.json pattern structurally, and the python-snap7 project is actively maintained. New project `tests/ZB.MOM.WW.OtOpcUa.Driver.S7.IntegrationTests/` with four moving parts: (a) `Snap7ServerFixture` — collection-scoped TCP probe on `localhost:1102` that sets `SkipReason` when the simulator's not running, matching the `ModbusSimulatorFixture` shape one directory over (same S7_SIM_ENDPOINT env var override convention for pointing at a real S7 CPU on port 102); (b) `PythonSnap7/` — `serve.ps1` wrapper + `server.py` shim + `s7_1500.json` seed profile + `README.md` documenting install / run / known limitations; (c) `S7_1500/S7_1500Profile.cs` — driver-side `S7DriverOptions` whose tag addresses map 1:1 to the JSON profile's seed offsets (DB1.DBW0 u16, DB1.DBW10 i16, DB1.DBD20 i32, DB1.DBD30 f32, DB1.DBX50.3 bool, DB1.DBW100 scratch); (d) `S7_1500SmokeTests` — three tests proving typed reads + write-then-read round-trip work through real S7netplus + real ISO-on-TCP + real snap7 server. Picked port 1102 default instead of S7-standard 102 because 102 is privileged on Linux + triggers Windows Firewall prompt; S7netplus 0.20 has a 5-arg `Plc(CpuType, host, port, rack, slot)` ctor that lets the driver honour `S7DriverOptions.Port`, but the existing driver code called the 4-arg overload + silently hardcoded 102. One-line driver fix (S7Driver.cs:87) threads `_options.Port` through — the S7 unit suite (58/58) still passes unchanged because every unit test uses a fake IS7Client that never sees the real ctor. Server seed-type matrix in `server.py` covers u8 / i8 / u16 / i16 / u32 / i32 / f32 / bool-with-bit / ascii (S7 STRING with max_len header). register_area takes the SrvArea enum value, not the string name — a 15-minute debug after the first test run caught that; documented inline. Per-driver test-fixture coverage docs — eight new files in `docs/drivers/` laying out what each driver's harness actually benchmarks vs. what's trusted from field deployments. Pattern mirrors the AbServer-Test-Fixture.md doc that shipped earlier in this arc: TL;DR → What the fixture is → What it actually covers → What it does NOT cover → When-to-trust table → Follow-up candidates → Key files. Ugly truth the survey made visible: Galaxy + Modbus + (now) S7 + AB CIP have real wire-level coverage; AB Legacy / TwinCAT / FOCAS / OpcUaClient are still contract-only because their libraries ship no fake + no open-source simulator exists (AB Legacy PCCC), no public simulator exists (FOCAS), the vendor SDK has no in-process fake (TwinCAT/ADS.NET), or the test wiring just hasn't happened yet (OpcUaClient could trivially loopback against this repo's own server — flagged as #215). Each doc names the specific follow-up route: Snap7 server for S7 (done), TwinCAT 3 developer-runtime auto-restart for TwinCAT, Tier-C out-of-process Host for FOCAS, lab rigs for AB Legacy + hardware-gated bits of the others. `docs/drivers/README.md` gains a coverage-map section linking all eight. Tracking tasks #215-#222 filed for each PR-able follow-up. Build clean (driver + integration project + docs); S7.Tests 58/58 (unchanged); S7.IntegrationTests 3/3 (new, verified end-to-end against a live python-snap7 server: `driver_reads_seeded_u16_through_real_S7comm`, `driver_reads_seeded_typed_batch`, `driver_write_then_read_round_trip_on_scratch_word`). Next fixture follow-up is #215 (OpcUaClient loopback against own server) — highest ROI of the remaining set, zero external deps. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
140 lines
6.0 KiB
Markdown
140 lines
6.0 KiB
Markdown
# OPC UA Client test fixture
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Coverage map + gap inventory for the OPC UA Client (gateway / aggregation)
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driver.
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**TL;DR: there is no integration fixture.** Tests mock the OPC UA SDK's
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`Session` + `Subscription` types directly; there is no upstream OPC UA
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server standup in CI. The irony is not lost — this repo *is* an OPC UA
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server, and the integration fixtures for `OpcUaApplicationHost`
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(`tests/ZB.MOM.WW.OtOpcUa.Server.Tests/OpcUaServerIntegrationTests.cs` +
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`OpcUaEquipmentWalkerIntegrationTests.cs`) stand up the server-side stack
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end-to-end. The client-side driver could in principle wire against one of
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those, but doesn't today.
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## What the fixture is
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Nothing at the integration layer.
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`tests/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests/` is unit-only. Tests
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inject fakes through the driver's construction path; the
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OPCFoundation.NetStandard `Session` surface is wrapped behind an interface
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the tests mock.
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## What it actually covers (unit only)
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The surface is broad because `OpcUaClientDriver` is the richest-capability
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driver in the fleet (it's a gateway for another OPC UA server, so it
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mirrors the full capability matrix):
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- `OpcUaClientDriverScaffoldTests` — `IDriver` lifecycle
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- `OpcUaClientReadWriteTests` — read + write lifecycle
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- `OpcUaClientSubscribeAndProbeTests` — monitored-item subscription + probe
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state transitions
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- `OpcUaClientDiscoveryTests` — `GetEndpoints` + endpoint selection
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- `OpcUaClientAttributeMappingTests` — OPC UA node attribute → driver value
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mapping
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- `OpcUaClientSecurityPolicyTests` — `SignAndEncrypt` / `Sign` / `None`
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policy negotiation contract
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- `OpcUaClientCertAuthTests` — cert store paths, revocation-list config
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- `OpcUaClientReconnectTests` — SDK reconnect hook + `TransferSubscriptions`
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across the disconnect boundary
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- `OpcUaClientFailoverTests` — primary → secondary session fallback per
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driver config
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- `OpcUaClientAlarmTests` — A&E severity bucket (1–1000 → Low / Medium /
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High / Critical), subscribe / unsubscribe / ack contract
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- `OpcUaClientHistoryTests` — historical data read + interpolation contract
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Capability surfaces whose contract is verified: `IDriver`, `ITagDiscovery`,
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`IReadable`, `IWritable`, `ISubscribable`, `IHostConnectivityProbe`,
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`IAlarmSource`, `IHistoryProvider`.
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## What it does NOT cover
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### 1. Real stack exchange
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No UA Secure Channel is ever opened. Every test mocks `Session.ReadAsync`,
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`Session.CreateSubscription`, `Session.AddItem`, etc. — the SDK itself is
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trusted. Certificate validation, signing, nonce handling, chunk assembly,
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keep-alive cadence — all SDK-internal and untested here.
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### 2. Subscription transfer across reconnect
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Contract test: "after a simulated reconnect, `TransferSubscriptions` is
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called with the right handles." Real behavior: SDK re-publishes against the
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new channel and some events can be lost depending on publish-queue state.
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The lossy window is not characterized.
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### 3. Large-scale subscription stress
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100+ monitored items with heterogeneous publish intervals under a single
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session — the shape that breaks publish-queue-size tuning in the wild — is
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not exercised.
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### 4. Real historian mappings
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`IHistoryProvider.ReadRawAsync` + `ReadProcessedAsync` +
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`ReadAtTimeAsync` + `ReadEventsAsync` are contract-mocked. Against a real
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historian (AVEVA Historian, Prosys historian, Kepware LocalHistorian) each
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has specific interpolation + bad-quality-handling quirks the contract test
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doesn't see.
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### 5. Real A&E events
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Alarm subscription is mocked via filtered monitored items; the actual
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`EventFilter` select-clause behavior against a server that exposes typed
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ConditionType events (non-base `BaseEventType`) is not verified.
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### 6. Authentication variants
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- Anonymous, UserName/Password, X509 cert tokens — each is contract-tested
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but not exchanged against a server that actually enforces each.
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- LDAP-backed `UserName` (matching this repo's server-side
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`LdapUserAuthenticator`) requires a live LDAP round-trip; not tested.
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## When to trust OpcUaClient tests, when to reach for a server
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| Question | Unit tests | Real upstream server |
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| --- | --- | --- |
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| "Does severity 750 bucket as High?" | yes | yes |
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| "Does the driver call `TransferSubscriptions` after reconnect?" | yes | yes |
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| "Does a real OPC UA read/write round-trip work?" | no | yes (required) |
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| "Does event-filter-based alarm subscription return ConditionType events?" | no | yes (required) |
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| "Does history read from AVEVA Historian return correct aggregates?" | no | yes (required) |
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| "Does the SDK's publish queue lose notifications under load?" | no | yes (stress) |
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## Follow-up candidates
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The easiest win here is to **wire the client driver tests against this
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repo's own server**. The integration test project
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`tests/ZB.MOM.WW.OtOpcUa.Server.Tests/OpcUaServerIntegrationTests.cs`
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already stands up a real OPC UA server on a non-default port with a seeded
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FakeDriver. An `OpcUaClientLiveLoopbackTests` that connects the client
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driver to that server would give:
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- Real Secure Channel negotiation
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- Real Session / Subscription / MonitoredItem exchange
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- Real read/write round-trip
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- Real certificate validation (the integration test already sets up PKI)
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It wouldn't cover upstream-server-specific quirks (AVEVA Historian, Kepware,
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Prosys), but it would cover 80% of the SDK surface the driver sits on top
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of.
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Beyond that:
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1. **Prosys OPC UA Simulation Server** — free, Windows-available, scriptable.
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2. **UaExpert Server-Side Simulator** — Unified Automation's sample server;
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good coverage of typed ConditionType events.
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3. **Dedicated historian integration lab** — only path for
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historian-specific coverage.
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## Key fixture / config files
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- `tests/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests/` — unit tests with
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mocked `Session`
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- `src/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient/OpcUaClientDriver.cs` — ctor +
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session-factory seam tests mock through
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- `tests/ZB.MOM.WW.OtOpcUa.Server.Tests/OpcUaServerIntegrationTests.cs` —
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the server-side integration harness a future loopback client test could
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piggyback on
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