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Phase 3 PR 68 -- OPC UA Client ITagDiscovery via recursive browse (Full strategy). Adds ITagDiscovery to OpcUaClientDriver. DiscoverAsync opens a single Remote folder on the IAddressSpaceBuilder and recursively browses from the configured root (default: ObjectsFolder i=85; override via OpcUaClientDriverOptions.BrowseRoot for scoped discovery). Browse uses non-obsolete Session.BrowseAsync(RequestHeader, ViewDescription, uint maxReferences, BrowseDescriptionCollection, ct) with HierarchicalReferences forward, subtypes included, NodeClassMask Object+Variable, ResultMask pulling BrowseName + DisplayName + NodeClass + TypeDefinition. Objects become sub-folders via builder.Folder; Variables become builder.Variable entries with FullName set to the NodeId.ToString() serialization so IReadable/IWritable can round-trip without re-resolving. Three safety caps added to OpcUaClientDriverOptions to bound runaway discovery: (1) MaxBrowseDepth default 10 -- deep enough for realistic OPC UA information models, shallow enough that cyclic graphs can't spin the browse forever. (2) MaxDiscoveredNodes default 10_000 -- caps memory on pathological remote servers. Once the cap is hit, recursion short-circuits and the partially-discovered tree is still projected into the local address space (graceful degradation rather than all-or-nothing). (3) BrowseRoot as an opt-in scope restriction string per driver-specs.md \u00A78 -- defaults to ObjectsFolder but operators with 100k-node servers can point it at a single subtree. Visited-set tracks NodeIds already visited to prevent infinite cycles on graphs with non-strict hierarchy (OPC UA models can have back-references). Transient browse failures on a subtree are swallowed -- the sub-branch stops but the rest of discovery continues, matching the Modbus driver's 'transient poll errors don't kill the loop' pattern. The driver's health surface reflects the network-level cascade via the probe loop (PR 69). Deferred to a follow-up PR: DataType resolution via a batch Session.ReadAsync(Attributes.DataType) after the browse so DriverAttributeInfo.DriverDataType is accurate instead of the current conservative DriverDataType.Int32 default; AccessLevel-derived SecurityClass instead of the current ViewOnly default; array-type detection via Attributes.ValueRank + ArrayDimensions. These need an extra wire round-trip per batch of variables + a NodeId -> DriverDataType mapping table; out of scope for PR 68 to keep browse path landable. Unit tests (OpcUaClientDiscoveryTests, 3 facts): DiscoverAsync_without_initialize_throws_InvalidOperationException (pre-init hits RequireSession); DiscoverAsync_rejects_null_builder (ArgumentNullException); Discovery_caps_are_sensible_defaults (asserts 10000 / 10 / null defaults documented above). NullAddressSpaceBuilder stub implements the full IAddressSpaceBuilder shape including IVariableHandle.MarkAsAlarmCondition (throws NotSupportedException since this PR doesn't wire alarms). Live-browse coverage against a real remote server is deferred to the in-process-server-fixture PR. 10/10 OpcUaClient.Tests pass. dotnet build clean.

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This commit is contained in:
Joseph Doherty
2026-04-19 01:17:21 -04:00
parent 89bd726fa8
commit db56a95819
3 changed files with 184 additions and 1 deletions
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55
tests/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests/OpcUaClientDiscoveryTests.cs Normal file
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using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests;
/// <summary>
/// Scaffold tests for <see cref="OpcUaClientDriver"/>'s <see cref="ITagDiscovery"/>
/// surface that don't require a live remote server. Live-browse coverage lands in a
/// follow-up PR once the in-process OPC UA server fixture is scaffolded.
/// </summary>
[Trait("Category", "Unit")]
public sealed class OpcUaClientDiscoveryTests
{
[Fact]
public async Task DiscoverAsync_without_initialize_throws_InvalidOperationException()
{
using var drv = new OpcUaClientDriver(new OpcUaClientDriverOptions(), "opcua-disco");
var builder = new NullAddressSpaceBuilder();
await Should.ThrowAsync<InvalidOperationException>(async () =>
await drv.DiscoverAsync(builder, TestContext.Current.CancellationToken));
}
[Fact]
public void DiscoverAsync_rejects_null_builder()
{
using var drv = new OpcUaClientDriver(new OpcUaClientDriverOptions(), "opcua-disco");
Should.ThrowAsync<ArgumentNullException>(async () =>
await drv.DiscoverAsync(null!, TestContext.Current.CancellationToken));
}
[Fact]
public void Discovery_caps_are_sensible_defaults()
{
var opts = new OpcUaClientDriverOptions();
opts.MaxDiscoveredNodes.ShouldBe(10_000, "bounds memory on runaway servers without clipping normal models");
opts.MaxBrowseDepth.ShouldBe(10, "deep enough for realistic info models; shallow enough for cycle safety");
opts.BrowseRoot.ShouldBeNull("null = default to ObjectsFolder i=85");
}
private sealed class NullAddressSpaceBuilder : IAddressSpaceBuilder
{
public IAddressSpaceBuilder Folder(string browseName, string displayName) => this;
public IVariableHandle Variable(string browseName, string displayName, DriverAttributeInfo attributeInfo)
=> new StubHandle();
public void AddProperty(string browseName, DriverDataType dataType, object? value) { }
public void AttachAlarmCondition(IVariableHandle sourceVariable, string alarmName, DriverAttributeInfo alarmInfo) { }
private sealed class StubHandle : IVariableHandle
{
public string FullReference => "stub";
public IAlarmConditionSink MarkAsAlarmCondition(AlarmConditionInfo info) => throw new NotSupportedException();
}
}
}