211 lines
9.9 KiB
Markdown
211 lines
9.9 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:** Wire-level coverage now exists via
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[opc-plc](https://github.com/Azure-Samples/iot-edge-opc-plc) — Microsoft
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Industrial IoT's OPC UA PLC simulator running in Docker (task #215). Real
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Secure Channel, real Session, real MonitoredItem exchange against an
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independent server implementation. Unit tests still carry the exhaustive
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capability matrix (cert auth / security policies / reconnect / failover /
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attribute mapping). Gaps remaining: upstream-server-specific quirks
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(historian aggregates, typed ConditionType events, SDK-publish-queue edge
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behavior under load) — opc-plc uses the same OPCFoundation stack internally
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so fully-independent-stack coverage needs `open62541/open62541` as a second
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image (follow-up).
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## What the fixture is
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**Integration layer** (task #215):
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`tests/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.IntegrationTests/` stands up
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`mcr.microsoft.com/iotedge/opc-plc:2.14.10` via `Docker/docker-compose.yml`
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on `opc.tcp://localhost:50000`. `OpcPlcFixture` probes the port at
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collection init + skips tests with a clear message when the container's
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not running (matches the Modbus/pymodbus + S7/python-snap7 skip pattern).
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Docker is the launcher — no PowerShell wrapper needed because opc-plc
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ships pre-containerized. Compose-file flags: `--ut` (unsecured transport
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advertised), `--aa` (auto-accept client certs — opc-plc's cert trust store
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resets on each spin-up), `--alm` (alarm simulation for IAlarmSource
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follow-up coverage), `--pn=50000` (port).
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**Unit layer**:
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`tests/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests/` is still the primary
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coverage. Tests 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
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### Integration (opc-plc Docker, task #215)
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- `OpcUaClientSmokeTests.Client_connects_and_reads_StepUp_node_through_real_OPC_UA_stack` —
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full Secure Channel + Session + `ns=3;s=StepUp` Read round-trip
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- `OpcUaClientSmokeTests.Client_reads_batch_of_varied_types_from_live_simulator` —
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batch Read of UInt32 / Int32 / Boolean; asserts `bool`-specific Variant
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decoding to catch a common attribute-mapping regression
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- `OpcUaClientSmokeTests.Client_subscribe_receives_StepUp_data_changes_from_live_server` —
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real `MonitoredItem` subscription against `ns=3;s=FastUInt1` (ticks every
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100 ms); asserts `OnDataChange` fires within 3 s of subscribe
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- `OpcUaClientReverseConnectSmokeTests.Driver_accepts_reverse_connect_from_opc_plc_rc_simulator` —
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reverse-connect (server-initiated) coverage. Driver binds
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`opc.tcp://0.0.0.0:4844`, the `opc-plc-rc` docker service dials in via
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`--rc opc.tcp://host.docker.internal:4844`, and a Read round-trips over
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the inbound socket. Gated on `OPCUA_RC_SIM=1` because the simulator
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requires `host.docker.internal` resolution which not every CI runner
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exposes.
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Wire-level surfaces verified: `IDriver` + `IReadable` + `ISubscribable` +
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`IHostConnectivityProbe` (via the Secure Channel exchange).
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### Unit
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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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## HistoryRead aggregate coverage
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PR-13 (issue #285) extended `HistoryAggregateType` from 5 to ~30 values
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matching the OPC UA Part 13 §5 catalog. The mapping itself
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(`OpcUaClientDriver.MapAggregateToNodeId`) is unit-tested via
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`OpcUaClientAggregateMappingTests`:
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- The full enum is swept with `Enum.GetValues<HistoryAggregateType>()` —
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every value must resolve to a non-null namespace-0 numeric `NodeId`.
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- The 25 new aggregates each assert against a reflection-resolved
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`Opc.Ua.ObjectIds.AggregateFunction_*` field by name, so a future SDK
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upgrade that renames a constant trips the test loudly.
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- The original 5 ordinals stay pinned to their pre-PR-13 NodeIds so existing
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config files / persisted enums keep working.
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This is **the well-known-NodeId test path** — the standard Part 13 NodeIds
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are stable across SDK versions; round-tripping each one against a live
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upstream is the integration suite's job and doesn't add coverage to the
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mapping table itself.
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`OpcUaClientAggregateSweepTests` is the integration counterpart. It loops
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every enum value against a real opc-plc upstream and asserts the wire path
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doesn't crash even when the simulator returns
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`BadAggregateNotSupported` for an aggregate it doesn't honour. opc-plc's
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default profile doesn't enable HistoryRead on the well-known nodes, so the
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test currently `Assert.Skip`s — re-enables when the fixture image is
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upgraded to a history-sim profile (`--useslowtypes --ut=10` or similar) and
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a known-good historized NodeId is wired into `OpcPlcProfile`.
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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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- `tests/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests/OpcUaClientAggregateMappingTests.cs`
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— Part 13 aggregate enum-to-NodeId mapping coverage (PR-13)
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- `tests/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.IntegrationTests/OpcUaClientAggregateSweepTests.cs`
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— wire-side aggregate sweep against opc-plc (build-only scaffold; PR-13)
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