feat(mtconnect): IWritable via agent observation writes

MTConnectDriver now implements IWritable over the Task-1 agent-client seam
(WriteObservationAsync -> the Agent's AllowPut POST surface). A write is
OBSERVATION INJECTION, not machine command: it sets what the Agent reports for
a DataItem, is visible to every consumer of that Agent, and is overwritten by
the next adapter/SHDR update. Off at two independent gates, both off by default
- the Agent's own AllowPut and the driver's write.enabled (Task 0).

Per-slot refusal order (never throws, strict N-in/N-out batch shape):
  write disabled          -> BadNotWritable
  no live client          -> BadNotConnected  (ReadAsync's existing convention)
  reference unresolved    -> BadNodeIdUnknown
  no resolvable device    -> BadNodeIdUnknown
  CONDITION category      -> BadNotWritable
  null / non-scalar value -> BadTypeMismatch
  agent refusal OR throw  -> BadCommunicationError
OperationCanceledException fills the remaining slots and returns. The Agent's
refusal text is logged at Warning and never enters DriverHealth.LastError
(type-only discipline); a refused write leaves health untouched.

Device-name resolution: TagBinding gains WriteTargetsByDataItemId, built in
BuildBinding from a probe-model walk that remembers which device each DataItem
was declared under (name, or id when nameless) plus its category. Falls back to
options.DeviceName; unresolvable -> BadNodeIdUnknown rather than a guess.
Values render via Convert.ToString(..., InvariantCulture) - so a Boolean writes
the invariant string "True"/"False", NOT "1"/"0". Arrays are refused rather
than rendered: Convert.ToString would emit the literal "System.Double[]", which
the Agent stores happily and which is invisible until read-back.

FINDING - the CurrentWrite bit does NOT key on SecurityClassification, and the
discovery stamping below is therefore cosmetic. Traced end to end: a browsed
leaf's SecurityClass survives into the browse session's AttributeInfo
(CapturedTreeBrowseSession.cs:53) and stops there - RawBrowseModal never reads
it, RawBrowseCommitMapper.MapLeaf hardcodes TagAccessLevel.Read, and Tag has no
SecurityClass column. AddressSpaceComposer:746/:809 sets Writable purely from
Tag.AccessLevel == ReadWrite; AddressSpaceApplier ANDs !IsArray;
OtOpcUaNodeManager.ComposeAccessLevel:2002 composes CurrentWrite from that
alone. Driver capability is never consulted at compose time either - IWritable
is checked only at runtime in DriverInstanceActor:755. Consequences: (a) raw
tags already committed keep their authored AccessLevel, so nothing this commit
does makes an existing node writable; (b) an operator must still set the tag to
ReadWrite for an MTConnect write to be reachable over OPC UA; (c) conversely a
ReadWrite tag on a non-IWritable driver has always advertised CurrentWrite and
failed only at the actor - pre-existing, not touched here.

Discovery stamps CanWrite(writeEnabled, dataItem) = write.enabled && !CONDITION
-> Operate, else ViewOnly - kept honest so the browse never advertises a tier
the write path would refuse (MQTT's CanWrite principle), with the caveat above
recorded verbatim at the call site.

Status-code constants are spelled WITHOUT MqttDriver's "Status" prefix, to
match the two this file already declares (BadCommunicationError,
BadNotConnected). StatusCodeParityTests strips either spelling and passes.

TDD: WriteAsync landed first as a NotImplementedException scaffold - 19 of 20
new tests red on behaviour, 1 (the capability assertion) green on the scaffold
- then implemented. MTConnectFactoryTests' "not_writable" characterization test
is rewritten to pin the new truth, and is the guard for the concrete-return
contract the factory remark explains.

Tests: 532 passed / 0 failed (was ~509). Full solution build: 0 errors,
0 warnings; OTOPCUA0001 clean.
This commit is contained in:
Joseph Doherty
2026-08-05 06:36:08 -04:00
parent 3b8b5a77e1
commit b29623cf99
6 changed files with 868 additions and 32 deletions
@@ -8,9 +8,12 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
/// current value from the Agent's <c>/current</c> snapshot / <c>/sample</c> stream by that id.
/// </summary>
/// <param name="FullName">
/// The MTConnect DataItem's <c>id</c> attribute (the Agent's <c>/probe</c> response). This is
/// the driver's reference for read/subscribe — MTConnect is a read-only source protocol, so
/// there is no corresponding write path.
/// The MTConnect DataItem's <c>id</c> attribute (the Agent's <c>/probe</c> response). This is the
/// driver's reference for read, subscribe <b>and write</b> — the write being an <i>observation
/// injection</i> through the Agent's <c>AllowPut</c> surface
/// (<c>POST {agent}/{device}?{id}={value}</c>), which sets what the Agent reports for the DataItem
/// rather than commanding the machine. It is off unless both the Agent's <c>AllowPut</c> and the
/// driver's <c>write.enabled</c> say otherwise, and CONDITION-category items are excluded.
/// </param>
/// <param name="DriverDataType">Logical data type the DataItem's value is coerced to.</param>
/// <param name="IsArray">
@@ -44,12 +44,23 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
/// </para>
/// <para>
/// <b>Scope.</b> This type implements <see cref="IDriver"/>, <see cref="IReadable"/>,
/// <see cref="ISubscribable"/>, <see cref="ITagDiscovery"/>,
/// <see cref="IWritable"/>, <see cref="ISubscribable"/>, <see cref="ITagDiscovery"/>,
/// <see cref="IHostConnectivityProbe"/> and <see cref="IRediscoverable"/> — the last two
/// built on state this class already caches (the Agent <c>instanceId</c> and the probe
/// model). There is deliberately no <c>IWritable</c>: MTConnect is a read-only protocol,
/// which is also why every discovered leaf is
/// <see cref="SecurityClassification.ViewOnly"/>.
/// model).
/// </para>
/// <para>
/// <b><see cref="IWritable"/> is <i>observation injection</i>, not machine command, and it is
/// off by default.</b> A write goes to the Agent's <c>AllowPut</c> surface
/// (<c>POST {agent}/{device}?{dataItemId}={value}</c>) and sets what the Agent <i>reports</i>
/// for that DataItem — visible to every consumer of that Agent, and overwritten by the next
/// adapter/SHDR update. Nothing reaches the CNC. It is therefore gated twice, and off at both
/// gates by default: the Agent's own <c>AllowPut</c> (<c>agent.cfg</c>) and this driver's
/// <see cref="MTConnectWriteOptions.Enabled"/>. Either gate alone leaves the shipped read-only
/// behaviour byte-for-byte unchanged. CONDITION data items are excluded — they carry alarm
/// semantics and a different <c>level|text</c> wire format. MTConnect <b>Interfaces</b>, the
/// protocol's own request/response handshake, remains deferred and is a different mechanism
/// entirely (see <c>docs/plans/2026-08-05-mtconnect-writeback-design.md</c> §2.1).
/// </para>
/// <para>
/// <b>The read path never writes the shared observation index</b> — see
@@ -60,15 +71,43 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
/// <see cref="AgentSession.ProbeModel"/> (see <see cref="RunProbeLoopAsync"/>).
/// </para>
/// </remarks>
public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDiscovery, IHostConnectivityProbe, IRediscoverable
public sealed class MTConnectDriver
: IDriver, IReadable, IWritable, ISubscribable, ITagDiscovery, IHostConnectivityProbe, IRediscoverable
{
/// <summary>
/// The Agent could not be reached, answered unusably, or blew the per-call deadline. Distinct
/// from the index's <c>BadNoCommunication</c>, which means the Agent answered and said the
/// machine has no value — the two failures need different operator responses.
/// machine has no value — the two failures need different operator responses. On the write
/// path it also covers an Agent that answered and <i>refused</i> — see <see cref="WriteAsync"/>.
/// </summary>
private const uint BadCommunicationError = 0x80050000u;
// ---- Write status codes ----
//
// NAMED constants, never inline literals: StatusCodeParityTests checks each against the pinned SDK
// by reflection and can only see a named const (Gitea #497/#519). The names must match
// Opc.Ua.StatusCodes members exactly. Spelled WITHOUT the "Status" prefix MqttDriver uses, to match
// the two this file already declares (the parity guard strips either spelling).
/// <summary>
/// The reference names no DataItem this driver serves, or names one whose owning device cannot
/// be resolved — there is no Agent URL a write could be addressed to.
/// </summary>
private const uint BadNodeIdUnknown = 0x80340000u;
/// <summary>
/// Writing is switched off (<c>write.enabled</c>), or the DataItem is CONDITION-category. The
/// honest answer to "can I write this?", and deliberately not a communication failure: nothing
/// was attempted and no Agent was involved.
/// </summary>
private const uint BadNotWritable = 0x803B0000u;
/// <summary>
/// The supplied value has no invariant string form a PUT could carry — <c>null</c>, or a
/// non-scalar (see <see cref="TryFormatValue"/>).
/// </summary>
private const uint BadTypeMismatch = 0x80740000u;
/// <summary>
/// There is no Agent client at all: the driver has not been initialized, its initialize
/// faulted, or it has been shut down. Deliberately not one of the index's codes — none of
@@ -694,6 +733,200 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
}
}
// ---- IWritable: observation injection through the Agent's AllowPut surface ----
/// <summary>
/// Sets the Agent's reported observation for each requested reference, through its
/// <c>AllowPut</c> surface. Returns one status per request, in request order.
/// </summary>
/// <param name="writes">The requested writes.</param>
/// <param name="cancellationToken">Cancellation for the batch.</param>
/// <returns>One <see cref="WriteResult"/> per request, in request order.</returns>
/// <remarks>
/// <para>
/// <b>This writes the Agent, not the machine</b> — see the class remarks. Good here means
/// "the Agent took the observation", which is a stronger statement than MQTT's optimistic
/// "published" (the Agent answers) and a weaker one than a device acknowledgement (no
/// MTConnect Agent speaks for the machine). The next adapter update for that DataItem
/// overwrites what was written, and the ordinary <c>/sample</c> ingest path is what
/// corrects the node.
/// </para>
/// <para>
/// <b>Never throws, and one bad slot never fails the batch</b> — matching
/// <see cref="ReadAsync"/>. Failing the whole call would let one stale reference reject
/// every other write in the same OPC UA request. Even cancellation returns a full-length
/// batch rather than propagating, so the node-manager can tell which slots were attempted.
/// </para>
/// <para>
/// <b>Refusal order is fixed, and each step answers a different operator question:</b>
/// writing switched off ⇒ <c>BadNotWritable</c>; no live client ⇒ <c>BadNotConnected</c>
/// (this driver is not running — <see cref="ReadAsync"/>'s convention); the reference
/// resolves to no DataItem, or to one whose owning device cannot be named ⇒
/// <c>BadNodeIdUnknown</c>; CONDITION category ⇒ <c>BadNotWritable</c>; no invariant string
/// form ⇒ <c>BadTypeMismatch</c>; and only then the Agent, whose refusal <b>or</b> whose
/// unreachability ⇒ <c>BadCommunicationError</c>.
/// </para>
/// <para>
/// <b>The Agent's refusal text is logged, never stored.</b> It goes to a Warning line and
/// nowhere near <see cref="DriverHealth.LastError"/>, which is type-only by repo-wide
/// discipline — and a refused write is not evidence the read path degraded, so health is
/// left exactly as it is (unlike <see cref="DegradeAfterReadFailure"/>).
/// </para>
/// </remarks>
/// <exception cref="ArgumentNullException"><paramref name="writes"/> is <c>null</c> — a caller bug.</exception>
public async Task<IReadOnlyList<WriteResult>> WriteAsync(
IReadOnlyList<WriteRequest> writes, CancellationToken cancellationToken)
{
ArgumentNullException.ThrowIfNull(writes);
if (writes.Count == 0)
{
return [];
}
// Read once each, for the same reason ReadAsync does: every slot in this batch is judged
// against ONE options document and ONE tag table, never half against a table a concurrent
// re-initialize just replaced.
var options = _options;
var client = Volatile.Read(ref _session)?.Client;
var binding = Volatile.Read(ref _binding);
var results = new WriteResult[writes.Count];
for (var i = 0; i < writes.Count; i++)
{
var request = writes[i];
if (!options.Write.Enabled)
{
results[i] = new WriteResult(BadNotWritable);
continue;
}
if (client is null)
{
results[i] = new WriteResult(BadNotConnected);
continue;
}
if (!binding.TryResolveWriteTarget(request.FullReference, out var dataItemId, out var target)
|| target.DeviceName is null)
{
results[i] = new WriteResult(BadNodeIdUnknown);
continue;
}
if (target.IsCondition)
{
results[i] = new WriteResult(BadNotWritable);
continue;
}
if (!TryFormatValue(request.Value, out var text))
{
results[i] = new WriteResult(BadTypeMismatch);
continue;
}
try
{
var outcome = await client
.WriteObservationAsync(target.DeviceName, dataItemId, text, cancellationToken)
.ConfigureAwait(false);
if (outcome.Accepted)
{
results[i] = new WriteResult(0u);
continue;
}
_logger.LogWarning(
"MTConnect driver {DriverInstanceId}: {AgentUri} refused the write of '{Value}' to DataItem '{DataItemId}' on device '{DeviceName}' — {AgentError}. Check the Agent's AllowPut / AllowPutFrom settings and that the DataItem exists.",
_driverInstanceId, options.AgentUri, text, dataItemId, target.DeviceName, outcome.AgentError);
results[i] = new WriteResult(BadCommunicationError);
}
catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
{
// Caller-cancelled: fill the remainder rather than throwing, so the batch shape holds.
for (var j = i; j < writes.Count; j++)
{
results[j] = new WriteResult(BadCommunicationError);
}
return results;
}
catch (Exception ex)
{
// A transport failure, a blown per-call deadline, or a disposed client. Logged with the
// exception (its TYPE is the diagnosis) and reported per slot; health is untouched.
_logger.LogWarning(
ex,
"MTConnect driver {DriverInstanceId} could not write DataItem '{DataItemId}' on device '{DeviceName}' to {AgentUri}.",
_driverInstanceId, dataItemId, target.DeviceName, options.AgentUri);
results[i] = new WriteResult(BadCommunicationError);
}
}
return results;
}
/// <summary>
/// Renders a value to the invariant string a PUT query carries, or reports that it has no such
/// form.
/// </summary>
/// <param name="value">The value the OPC UA client supplied.</param>
/// <param name="text">The rendered value; empty when this returns <see langword="false"/>.</param>
/// <returns><see langword="false"/> for a value that must be refused as a type mismatch.</returns>
/// <remarks>
/// <para>
/// <b><see cref="CultureInfo.InvariantCulture"/> is load-bearing.</b> A comma decimal
/// separator produces a value the Agent accepts and every consumer reads back as a
/// different number. Booleans render as <c>True</c>/<c>False</c> —
/// <see cref="bool.ToString()"/> is culture-independent, so that IS the invariant form, and
/// it is what an MTConnect consumer will see verbatim.
/// </para>
/// <para>
/// <b>Arrays are refused rather than rendered.</b>
/// <see cref="Convert.ToString(object, IFormatProvider)"/> falls back to
/// <see cref="object.ToString"/> for a non-<see cref="IConvertible"/> value, so an array
/// would be written as the literal text <c>System.Double[]</c> — which the Agent stores
/// happily, making the corruption invisible until someone reads the observation back.
/// TIME_SERIES / DATA_SET writes are out of scope for v1.
/// </para>
/// </remarks>
private static bool TryFormatValue(object? value, out string text)
{
text = string.Empty;
// A PUT query has no null to send, and the empty string is a real observation rather than an
// absence — so "no value" is refused instead of being silently turned into one.
if (value is null or Array)
{
return false;
}
string? rendered;
try
{
rendered = Convert.ToString(value, CultureInfo.InvariantCulture);
}
catch (Exception ex) when (ex is FormatException or InvalidCastException or OverflowException)
{
return false;
}
if (rendered is null)
{
return false;
}
text = rendered;
return true;
}
// ---- ISubscribable: ONE shared /sample long poll behind every handle ----
/// <inheritdoc/>
@@ -940,7 +1173,11 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
// Read once: a concurrent re-initialize must not scope half this walk to one device and half
// to another.
var deviceScope = _options.DeviceName?.Trim();
// Both read once, together: a concurrent re-initialize must not scope half this walk to one
// device and half to another, nor stamp half its leaves writable and half not.
var options = _options;
var deviceScope = options.DeviceName?.Trim();
var writeEnabled = options.Write.Enabled;
var devices = 0;
var variables = 0;
@@ -966,7 +1203,7 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
}
devices++;
variables += StreamContainer(device, builder.Folder(name, name));
variables += StreamContainer(device, builder.Folder(name, name), writeEnabled);
}
// A configured scope that matches NO device is an authoring error — almost always a typo or
@@ -1003,7 +1240,14 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
/// picker exists to show. Recursion depth is bounded by the parser, which refuses a probe
/// document nested beyond its own limit.
/// </remarks>
private static int StreamContainer(IMTConnectComponentContainer container, IAddressSpaceBuilder scope)
/// <param name="container">The device or component whose data items are being streamed.</param>
/// <param name="scope">The builder folder they belong under.</param>
/// <param name="writeEnabled">
/// <see cref="MTConnectWriteOptions.Enabled"/>, read once by the caller so one walk cannot
/// stamp half its leaves under an old options document and half under a new one.
/// </param>
private static int StreamContainer(
IMTConnectComponentContainer container, IAddressSpaceBuilder scope, bool writeEnabled)
{
var streamed = 0;
@@ -1037,9 +1281,21 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
IsArray: inferred.IsArray,
ArrayDim: inferred.ArrayDim,
// MTConnect is read-only and this driver implements no IWritable, so the tier
// that is read-only from OPC UA is the only honest one.
SecurityClass: SecurityClassification.ViewOnly,
// Operate exactly for the leaves WriteAsync would accept — the "a node cannot
// advertise writability the driver would refuse" principle. With write.enabled
// off (the default) every leaf stays ViewOnly, which is what this driver shipped.
//
// ⚠️ This does NOT make the committed tag writable over OPC UA, and must not be
// read as doing so. Nothing persists SecurityClass: RawBrowseCommitMapper.MapLeaf
// hardcodes TagAccessLevel.Read, Tag has no SecurityClass column, and the
// CurrentWrite bit is composed from Tag.AccessLevel alone
// (OtOpcUaNodeManager.ComposeAccessLevel). The stamp reaches the browse session's
// attribute side-channel and stops there, so an operator still has to author
// ReadWrite on the tag. It is kept honest anyway — a browse that advertised
// ViewOnly for a leaf this driver now writes would be a lie an operator reads.
SecurityClass: CanWrite(writeEnabled, dataItem)
? SecurityClassification.Operate
: SecurityClassification.ViewOnly,
// Historization is authored per tag, never inferred from a device model.
IsHistorized: false,
@@ -1067,12 +1323,26 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
continue;
}
streamed += StreamContainer(component, scope.Folder(name, name));
streamed += StreamContainer(component, scope.Folder(name, name), writeEnabled);
}
return streamed;
}
/// <summary>
/// Whether <see cref="WriteAsync"/> would accept a write to <paramref name="dataItem"/> — the
/// browse-time answer, asked of the same two facts the runtime asks of.
/// </summary>
/// <param name="writeEnabled">Whether <c>write.enabled</c> is on.</param>
/// <param name="dataItem">The declared data item.</param>
/// <remarks>
/// The device-name leg of the runtime refusal is not asked here and does not need to be: a
/// leaf reached by this walk is <i>inside</i> a device the model declares, so its owning device
/// is known by construction.
/// </remarks>
private static bool CanWrite(bool writeEnabled, MTConnectDataItem dataItem) =>
writeEnabled && !IsCondition(dataItem.Category);
/// <summary>
/// Whether a device is in this instance's configured scope. An unset scope is agent-wide.
/// </summary>
@@ -2933,10 +3203,13 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
if (options.RawTags.Count == 0)
{
MTConnectTagDefinition[] only = [.. definitions.Values];
return new TagBinding(
FrozenDictionary<string, string>.Empty,
FrozenDictionary<string, IReadOnlyList<string>>.Empty,
[.. definitions.Values]);
only,
BuildWriteTargets(only, probeModel, options.DeviceName));
}
var declared = IndexProbeDataItems(probeModel);
@@ -2982,13 +3255,106 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
}
}
MTConnectTagDefinition[] indexTags = [.. definitions.Values];
return new TagBinding(
idByRawPath.ToFrozenDictionary(StringComparer.Ordinal),
rawPathsById.ToFrozenDictionary(
pair => pair.Key,
pair => (IReadOnlyList<string>)pair.Value,
StringComparer.Ordinal),
[.. definitions.Values]);
indexTags,
BuildWriteTargets(indexTags, probeModel, options.DeviceName));
}
/// <summary>
/// Derives the write-addressing table: for every DataItem this driver serves, the device the
/// Agent's <c>AllowPut</c> URL must name, and whether the item is CONDITION-category.
/// </summary>
/// <param name="definitions">Every DataItem the binding serves (the union of both authoring surfaces).</param>
/// <param name="probeModel">The Agent's device model when one has been fetched; else null.</param>
/// <param name="configuredDeviceName">
/// <see cref="MTConnectDriverOptions.DeviceName"/> — the fallback for a DataItem the
/// <c>/probe</c> model does not declare.
/// </param>
/// <remarks>
/// <para>
/// <b>The device name is derived, not authored.</b> The Agent's PUT surface is addressed
/// per device even on a single-device Agent, and the probe model already says which device
/// owns which DataItem — so a multi-device Agent is addressed correctly with no extra
/// config. Config is the fallback, for the dataItemId-keyed authoring surface (the driver
/// CLI) and for a DataItem the Agent has since stopped declaring.
/// </para>
/// <para>
/// <b>A null <see cref="WriteTarget.DeviceName"/> is a refusal, not a default.</b> Neither
/// the model nor config names a device, so there is no URL to POST to; guessing one yields
/// a 404 an operator reads as "the Agent is broken". <see cref="WriteAsync"/> reports it as
/// <c>BadNodeIdUnknown</c>.
/// </para>
/// <para>
/// <b>The category comes from the probe first, the authored blob second.</b> The Agent is
/// the authority on what a DataItem is; a blob's <c>mtCategory</c> is optional metadata
/// that may be absent (browse-commit writes only the address) or stale.
/// </para>
/// </remarks>
private static FrozenDictionary<string, WriteTarget> BuildWriteTargets(
IReadOnlyList<MTConnectTagDefinition> definitions,
MTConnectProbeModel? probeModel,
string? configuredDeviceName)
{
if (definitions.Count == 0)
{
return FrozenDictionary<string, WriteTarget>.Empty;
}
var owners = IndexProbeOwners(probeModel);
var fallback = string.IsNullOrWhiteSpace(configuredDeviceName) ? null : configuredDeviceName.Trim();
var targets = new Dictionary<string, WriteTarget>(definitions.Count, StringComparer.Ordinal);
foreach (var definition in definitions)
{
if (definition is null || string.IsNullOrWhiteSpace(definition.FullName)) continue;
var owner = owners.TryGetValue(definition.FullName, out var declared) ? declared : null;
targets[definition.FullName] = new WriteTarget(
owner?.DeviceName ?? fallback,
IsCondition(owner?.Category ?? definition.MtCategory));
}
return targets.ToFrozenDictionary(StringComparer.Ordinal);
}
/// <summary>
/// Flattens a device model into a <c>dataItemId → owning device</c> lookup; null ⇒ empty.
/// Separate from <see cref="IndexProbeDataItems"/> because this one must remember which device
/// the walk was inside, which a flat DataItem lookup has thrown away.
/// </summary>
/// <param name="probeModel">The Agent's device model, or null.</param>
private static FrozenDictionary<string, DataItemOwner> IndexProbeOwners(MTConnectProbeModel? probeModel)
{
if (probeModel is null) return FrozenDictionary<string, DataItemOwner>.Empty;
var map = new Dictionary<string, DataItemOwner>(StringComparer.Ordinal);
foreach (var device in probeModel.Devices)
{
if (device is null) continue;
// The same name/id fallback the browse tree uses: an Agent addresses a device by its
// name, and by its id when it declares no name.
var deviceName = FolderName(device.Name, device.Id);
var owner = new DataItemOwner(
string.IsNullOrWhiteSpace(deviceName) ? null : deviceName, Category: null);
foreach (var dataItem in device.AllDataItems())
{
if (dataItem is null || string.IsNullOrWhiteSpace(dataItem.Id)) continue;
map[dataItem.Id] = owner with { Category = dataItem.Category };
}
}
return map.ToFrozenDictionary(StringComparer.Ordinal);
}
/// <summary>
@@ -3174,11 +3540,45 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
/// <see cref="MTConnectDriverOptions.RawTags"/>. This is how a raw tag's declared (or
/// probe-inferred) <c>DriverDataType</c> reaches the coercion.
/// </param>
/// <param name="WriteTargetsByDataItemId">
/// How each DataItem is addressed on the Agent's <c>AllowPut</c> surface, and whether it is
/// CONDITION-category — see <see cref="BuildWriteTargets"/>. Keyed by DataItem id, so it
/// doubles as the write path's "is this a reference I serve at all?" test: a miss is
/// <c>BadNodeIdUnknown</c>, exactly as an index miss is on the read path.
/// </param>
private sealed record TagBinding(
FrozenDictionary<string, string> DataItemIdByRawPath,
FrozenDictionary<string, IReadOnlyList<string>> RawPathsByDataItemId,
IReadOnlyList<MTConnectTagDefinition> IndexTags)
IReadOnlyList<MTConnectTagDefinition> IndexTags,
FrozenDictionary<string, WriteTarget> WriteTargetsByDataItemId)
{
/// <summary>
/// Resolves a write reference to the DataItem id and the Agent address it writes through.
/// </summary>
/// <param name="reference">The caller's reference (a RawPath under v3, or a DataItem id).</param>
/// <param name="dataItemId">The resolved DataItem id; empty when this returns false.</param>
/// <param name="target">Where and whether it can be written; <c>default</c> when false.</param>
/// <returns><see langword="false"/> when no DataItem this driver serves answers to that reference.</returns>
/// <remarks>
/// Stricter than <see cref="ToDataItemId"/>, deliberately. A read may fall through to an
/// index miss and report itself; a write that fell through would POST an arbitrary
/// operator string at the Agent as if it were a DataItem id — the Agent's answer to which
/// is a refusal that reads like a comms fault. Unknown is answered here, before the wire.
/// </remarks>
public bool TryResolveWriteTarget(string? reference, out string dataItemId, out WriteTarget target)
{
dataItemId = ToDataItemId(reference);
if (dataItemId.Length != 0 && WriteTargetsByDataItemId.TryGetValue(dataItemId, out target))
{
return true;
}
target = default;
return false;
}
/// <summary>
/// Translates a subscriber/read reference to the DataItem id the index is keyed by.
/// </summary>
@@ -3218,6 +3618,24 @@ public sealed class MTConnectDriver : IDriver, IReadable, ISubscribable, ITagDis
}
}
/// <summary>
/// Everything <see cref="WriteAsync"/> needs to decide one slot before it touches the network.
/// </summary>
/// <param name="DeviceName">
/// The device path segment of the Agent PUT URL, or <c>null</c> when neither the probe model
/// nor config names one — which is a refusal, not a default (see <see cref="BuildWriteTargets"/>).
/// </param>
/// <param name="IsCondition">
/// Whether the DataItem is CONDITION-category. Excluded from v1 writes: a condition PUT carries
/// alarm semantics and a different <c>level|text</c> wire format.
/// </param>
private readonly record struct WriteTarget(string? DeviceName, bool IsCondition);
/// <summary>The device a DataItem was declared under, and the category it was declared with.</summary>
/// <param name="DeviceName">The owning device's name (or id); null when it declares neither.</param>
/// <param name="Category">The DataItem's <c>category</c> attribute as the Agent spelled it.</param>
private sealed record DataItemOwner(string? DeviceName, string? Category);
/// <summary>
/// One live subscription: its handle and the references it wants. Both are effectively
/// immutable once registered, so the pump reads <see cref="References"/> without a lock —
@@ -31,12 +31,20 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect;
/// </para>
/// <para>
/// <b>The instance is returned as its concrete type.</b> The runtime resolves every optional
/// capability (<see cref="IReadable"/>, <see cref="ISubscribable"/>,
/// capability (<see cref="IReadable"/>, <see cref="IWritable"/>, <see cref="ISubscribable"/>,
/// <see cref="ITagDiscovery"/>, <see cref="IHostConnectivityProbe"/>,
/// <see cref="IRediscoverable"/>) by pattern-matching the object
/// <see cref="DriverFactoryRegistry"/> hands back, so nothing here may narrow it — a
/// narrowed return is how a capability ends up implemented but never dispatched. There is
/// deliberately no <c>IWritable</c>: the MTConnect Agent surface is read-only.
/// narrowed return is how a capability ends up implemented but never dispatched.
/// <see cref="IWritable"/> is the standing example: it was added to
/// <see cref="MTConnectDriver"/> with no change whatsoever to this file, and would have been
/// silently undispatched had the return type ever been narrowed to <see cref="IDriver"/>.
/// </para>
/// <para>
/// <b>Registering the factory does not enable writing.</b> An MTConnect write is observation
/// injection through the Agent's <c>AllowPut</c> surface and is off at two independent gates
/// — the Agent's <c>agent.cfg</c> and the driver's own <c>write.enabled</c> (default
/// <see langword="false"/>). See <see cref="MTConnectDriver"/>'s remarks.
/// </para>
/// </remarks>
public static class MTConnectDriverFactoryExtensions
@@ -45,12 +45,16 @@ public sealed class MTConnectDiscoverTests
"dev1_system_cond",
];
private static MTConnectDriverOptions Opts(string? deviceName = null) =>
private static MTConnectDriverOptions Opts(string? deviceName = null, bool writeEnabled = false) =>
new()
{
AgentUri = AgentUri,
DeviceName = deviceName,
// Off unless a test says otherwise — the shipped default, and what every pre-write-back
// expectation in this file was written against.
Write = new MTConnectWriteOptions { Enabled = writeEnabled },
// Discovery is a pure read of the /probe device model: it must enumerate what the Agent
// declares, NOT what an operator has already authored. Left empty on purpose so a driver
// that streamed its authored tag table instead could not pass.
@@ -324,10 +328,10 @@ public sealed class MTConnectDiscoverTests
}
/// <summary>
/// MTConnect is a read-only protocol and this driver implements no <c>IWritable</c>, so every
/// browsed leaf is <see cref="SecurityClassification.ViewOnly"/> — the tier that is read-only
/// from OPC UA. Nothing is historized by discovery either: historization is authored per tag,
/// never inferred from a device model.
/// Write-back is off by default, so every browsed leaf is
/// <see cref="SecurityClassification.ViewOnly"/> — the tier that is read-only from OPC UA, and
/// exactly what this driver shipped. Nothing is historized by discovery either: historization
/// is authored per tag, never inferred from a device model.
/// </summary>
[Fact]
public async Task Discover_streams_every_leaf_view_only_and_not_historized()
@@ -341,6 +345,47 @@ public sealed class MTConnectDiscoverTests
cap.Variables.ShouldAllBe(v => v.Attr.Source == NodeSourceKind.Driver);
}
/// <summary>
/// With <c>write.enabled</c> on, the same probe model browses <see cref="SecurityClassification.Operate"/>
/// — but only for the leaves <c>WriteAsync</c> would actually accept. A browse that advertised a
/// tier the write path refuses is the "silent no-op in a new costume" failure MQTT's
/// <c>CanWrite</c> pins against; the flag is the ONLY difference between this test and the one
/// above, so a driver that ignored it could not pass both.
/// </summary>
[Fact]
public async Task Discover_streams_writable_leaves_as_operate_when_write_is_enabled()
{
var (driver, _) = await InitializedDriverAsync(Opts(writeEnabled: true));
var cap = await DiscoverAsync(driver);
var writable = cap.Variables.Where(v => !v.Attr.IsAlarm).ToList();
// Counted, not just ShouldAllBe: an empty sequence satisfies ShouldAllBe vacuously, so a
// discovery that streamed nothing at all would otherwise pass this test.
writable.Count.ShouldBe(FixtureDataItemIds.Length - 1);
writable.ShouldAllBe(v => v.Attr.SecurityClass == SecurityClassification.Operate);
}
/// <summary>
/// A CONDITION data item stays <see cref="SecurityClassification.ViewOnly"/> in <b>both</b>
/// modes: a condition PUT carries alarm semantics and a different <c>level|text</c> wire
/// format, so the write path refuses it and the browse must say so.
/// </summary>
/// <param name="writeEnabled">Whether the driver's write-back block is switched on.</param>
[Theory]
[InlineData(false)]
[InlineData(true)]
public async Task Discover_streams_a_condition_leaf_view_only_whether_or_not_write_is_enabled(bool writeEnabled)
{
var (driver, _) = await InitializedDriverAsync(Opts(writeEnabled: writeEnabled));
var cap = await DiscoverAsync(driver);
cap.Variables.Single(v => v.Attr.FullName == "dev1_system_cond")
.Attr.SecurityClass.ShouldBe(SecurityClassification.ViewOnly);
}
// ---- browse names ----
/// <summary>
@@ -207,19 +207,25 @@ public sealed class MTConnectFactoryTests
}
/// <summary>
/// The other half of the capability pin: MTConnect's Agent surface is read-only, so the
/// instance must NOT be <see cref="IWritable"/>. If it ever became writable, the write gate
/// would start offering an operation the protocol cannot honour.
/// The other half of the capability pin: the instance IS <see cref="IWritable"/>, so the
/// runtime's write gate dispatches to it. This is the seam the concrete return type exists for
/// — the capability was added to the driver with no change to the factory, and a narrowed
/// return would have left it implemented but never dispatched.
/// </summary>
/// <remarks>
/// <b>Dispatchable is not enabled.</b> The config below authors no <c>write</c> block, so this
/// instance refuses every write with <c>BadNotWritable</c> — and the Agent's own
/// <c>AllowPut</c> is a second, independent gate. See <c>MTConnectWriteTests</c>.
/// </remarks>
[Fact]
public void Registered_delegate_returns_an_instance_that_is_not_writable()
public void Registered_delegate_returns_an_instance_that_dispatches_writes()
{
var registry = new DriverFactoryRegistry();
MTConnectDriverFactoryExtensions.Register(registry);
IDriver driver = registry.TryGet("MTConnect")!("mt1", "{\"agentUri\":\"http://a:5000\"}");
(driver is IWritable).ShouldBeFalse("the MTConnect Agent surface is read-only");
(driver is IWritable).ShouldBeTrue("MTConnect must dispatch writes (the Agent AllowPut surface)");
}
/// <summary>Registering into a null registry is a wiring bug, not a silent no-op.</summary>
@@ -0,0 +1,356 @@
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Tests;
/// <summary>
/// <see cref="MTConnectDriver"/>'s <see cref="IWritable"/> leg — the batch contract, the per-slot
/// refusals, and the one thing the driver has to get right before the Agent is even dialled: which
/// device a DataItem belongs to.
/// </summary>
/// <remarks>
/// <para>
/// <b>The write itself is the live gate's job.</b> Everything below stops at the
/// <see cref="IMTConnectAgentClient"/> seam and asserts what the driver <i>asked</i> the Agent
/// for (<see cref="CannedAgentClient.Writes"/>), never that a fake was called for its own sake —
/// the same philosophy as <c>MqttDriverWriteTests</c>. What IS worth pinning offline is
/// everything that decides whether a write should reach an Agent at all, because that is where
/// a silent no-op would hide.
/// </para>
/// <para>
/// <b>A write is observation injection, not machine command</b> (design §2.2): it sets what the
/// Agent reports for a DataItem, and the next adapter update overwrites it. That is why the
/// feature is off at two independent gates — the Agent's <c>AllowPut</c>, and this driver's
/// <c>write.enabled</c> — and why the disabled leg below is the first test in the file.
/// </para>
/// </remarks>
public sealed class MTConnectWriteTests
{
private const string AgentUri = "http://fixture-agent:5000";
/// <summary>The device the canned <c>Fixtures/probe.xml</c> declares — <c>id="dev1" name="VMC-3Axis"</c>.</summary>
private const string FixtureDeviceName = "VMC-3Axis";
private const string PositionDataItemId = "dev1_pos";
private const string ConditionDataItemId = "dev1_system_cond";
private const string PositionRawPath = "Plant/MTConnect/dev1/Position";
private const string ConditionRawPath = "Plant/MTConnect/dev1/SystemCondition";
private const string UnknownRawPath = "Plant/MTConnect/dev1/NotATag";
private const uint Good = 0x00000000u;
private const uint BadNodeIdUnknown = 0x80340000u;
private const uint BadNotWritable = 0x803B0000u;
private const uint BadTypeMismatch = 0x80740000u;
private const uint BadCommunicationError = 0x80050000u;
private const uint BadNotConnected = 0x808A0000u;
private static CancellationToken Ct => TestContext.Current.CancellationToken;
/// <summary>One authored raw tag bound to a DataItem id, as the browse-commit flow writes it.</summary>
private static RawTagEntry Entry(string rawPath, string dataItemId) =>
new(rawPath, $$"""{"fullName":"{{dataItemId}}"}""", WriteIdempotent: false, DeviceName: "dev1");
private static MTConnectDriverOptions Opts(
bool writeEnabled = true, string? deviceName = null, params RawTagEntry[] rawTags) =>
new()
{
AgentUri = AgentUri,
DeviceName = deviceName,
Tags = [],
RawTags = rawTags,
Write = new MTConnectWriteOptions { Enabled = writeEnabled },
};
private static (MTConnectDriver Driver, CannedAgentClient Client) NewDriver(
MTConnectDriverOptions options, RecordingDriverLogger? logger = null)
{
var client = CannedAgentClient.FromFixtures();
return (new MTConnectDriver(options, "mt1", _ => client, logger), client);
}
private static async Task<(MTConnectDriver Driver, CannedAgentClient Client)> InitializedAsync(
MTConnectDriverOptions options, RecordingDriverLogger? logger = null)
{
var (driver, client) = NewDriver(options, logger);
await driver.InitializeAsync("{}", Ct);
return (driver, client);
}
/// <summary>The ordinary rig: write on, one writable position tag and the fixture's CONDITION item.</summary>
private static Task<(MTConnectDriver Driver, CannedAgentClient Client)> WritableDriverAsync(
RecordingDriverLogger? logger = null) =>
InitializedAsync(
Opts(
writeEnabled: true,
deviceName: null,
Entry(PositionRawPath, PositionDataItemId),
Entry(ConditionRawPath, ConditionDataItemId)),
logger);
// ---- the capability itself ----
[Fact]
public void MTConnectDriver_implements_IWritable()
// The interface's presence IS the feature: without it the runtime's capability dispatch never
// offers this driver a write, whatever a node advertises.
=> NewDriver(Opts()).Driver.ShouldBeAssignableTo<IWritable>();
// ---- the two independent gates ----
[Fact]
public async Task A_driver_with_write_disabled_refuses_every_slot_without_dialling_the_agent()
{
// The default. An existing deployment that never authors the block keeps today's read-only
// behaviour EXACTLY — including making no request an Agent could log or accept.
var (driver, client) = await InitializedAsync(
Opts(writeEnabled: false, deviceName: null, Entry(PositionRawPath, PositionDataItemId)));
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);
results.Count.ShouldBe(1);
results[0].StatusCode.ShouldBe(BadNotWritable);
client.Writes.ShouldBeEmpty();
}
[Fact]
public async Task A_write_before_initialize_reports_not_connected()
{
// Matches ReadAsync: "this driver is not running" is the only true statement available, and it
// is NOT the same operator problem as an Agent that answered and refused.
var (driver, _) = NewDriver(Opts(true, null, Entry(PositionRawPath, PositionDataItemId)));
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);
results[0].StatusCode.ShouldBe(BadNotConnected);
}
[Fact]
public async Task A_write_after_shutdown_reports_not_connected()
{
var (driver, _) = await WritableDriverAsync();
await driver.ShutdownAsync(Ct);
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);
results[0].StatusCode.ShouldBe(BadNotConnected);
}
// ---- per-slot refusals ----
[Fact]
public async Task An_unknown_reference_is_refused_in_its_own_slot()
{
var (driver, client) = await WritableDriverAsync();
var results = await driver.WriteAsync([new WriteRequest(UnknownRawPath, 1.0)], Ct);
results[0].StatusCode.ShouldBe(BadNodeIdUnknown);
client.Writes.ShouldBeEmpty();
}
[Fact]
public async Task A_condition_data_item_is_refused_as_not_writable()
{
// CONDITION PUTs carry alarm semantics and a different level|text wire format — excluded from
// v1. BadNotWritable, not BadTypeMismatch: the value was never the problem.
var (driver, client) = await WritableDriverAsync();
var results = await driver.WriteAsync([new WriteRequest(ConditionRawPath, "NORMAL")], Ct);
results[0].StatusCode.ShouldBe(BadNotWritable);
client.Writes.ShouldBeEmpty();
}
[Fact]
public async Task A_null_value_is_refused_as_a_type_mismatch()
{
// A write IS a URL query value; there is no null to send. Refusing beats writing the empty
// string, which the Agent would accept as a real observation.
var (driver, client) = await WritableDriverAsync();
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, null)], Ct);
results[0].StatusCode.ShouldBe(BadTypeMismatch);
client.Writes.ShouldBeEmpty();
}
[Fact]
public async Task An_array_value_is_refused_as_a_type_mismatch()
{
// Convert.ToString would happily render "System.Double[]" and the Agent would happily store it:
// a silent corruption visible only on read-back. Array/TIME_SERIES writes are out of scope.
var (driver, client) = await WritableDriverAsync();
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, new[] { 1.0, 2.0 })], Ct);
results[0].StatusCode.ShouldBe(BadTypeMismatch);
client.Writes.ShouldBeEmpty();
}
// ---- what actually reaches the seam ----
[Fact]
public async Task An_accepted_write_reports_good_and_names_the_owning_device_and_data_item()
{
// The device NAME is resolved from the /probe model, not from config: the Agent's PUT surface
// is addressed per device, and a multi-device Agent must be addressed correctly with no extra
// authoring. The RawPath is translated to the DataItem id, exactly as the read path does.
var (driver, client) = await WritableDriverAsync();
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);
results[0].StatusCode.ShouldBe(Good);
client.Writes.ShouldHaveSingleItem()
.ShouldBe((FixtureDeviceName, PositionDataItemId, "42.5"));
}
[Fact]
public async Task A_value_is_rendered_with_the_invariant_culture()
{
// A comma decimal separator would be accepted by the Agent and read back as a different number.
var (driver, client) = await WritableDriverAsync();
await driver.WriteAsync([new WriteRequest(PositionRawPath, 1234.5678d)], Ct);
client.Writes.ShouldHaveSingleItem().Value.ShouldBe("1234.5678");
}
[Fact]
public async Task A_boolean_is_rendered_as_its_invariant_true_false_string()
{
// Boolean.ToString is culture-independent, so the invariant rendering is "True"/"False" — NOT
// "1"/"0". Documented because it is the value an MTConnect consumer will see verbatim.
var (driver, client) = await WritableDriverAsync();
await driver.WriteAsync([new WriteRequest(PositionRawPath, true)], Ct);
client.Writes.ShouldHaveSingleItem().Value.ShouldBe("True");
}
// ---- device-name resolution ----
[Fact]
public async Task A_data_item_the_probe_does_not_declare_falls_back_to_the_configured_device()
{
// The dataItemId-keyed authoring surface (the driver CLI) and any tag whose DataItem the Agent
// has since dropped: config is the only device name available, and it is a real one.
var (driver, client) = await InitializedAsync(
Opts(writeEnabled: true, deviceName: "ConfiguredDevice", Entry(PositionRawPath, "not_in_probe")));
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 7)], Ct);
results[0].StatusCode.ShouldBe(Good);
client.Writes.ShouldHaveSingleItem().ShouldBe(("ConfiguredDevice", "not_in_probe", "7"));
}
[Fact]
public async Task A_data_item_with_no_resolvable_device_is_refused_as_an_unknown_node()
{
// Neither the probe model nor config names a device, so there is no URL to POST to. Refused
// rather than guessed: a wrong device path is a 404 the operator reads as "the Agent is broken".
var (driver, client) = await InitializedAsync(
Opts(writeEnabled: true, deviceName: null, Entry(PositionRawPath, "not_in_probe")));
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 7)], Ct);
results[0].StatusCode.ShouldBe(BadNodeIdUnknown);
client.Writes.ShouldBeEmpty();
}
// ---- how the Agent's own answers map ----
[Fact]
public async Task An_agent_refusal_maps_to_a_communication_error_and_logs_the_agents_own_text()
{
var logger = new RecordingDriverLogger();
var (driver, client) = await WritableDriverAsync(logger);
client.WriteOutcome = new MTConnectWriteOutcome(Accepted: false, AgentError: "UNSUPPORTED: no such device");
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);
results[0].StatusCode.ShouldBe(BadCommunicationError);
logger.WarningsSnapshot().ShouldContain(w => w.Contains("UNSUPPORTED: no such device", StringComparison.Ordinal));
}
[Fact]
public async Task An_agent_refusal_never_reaches_the_health_LastError()
{
// Type-only discipline: LastError carries an exception TYPE, never Agent-authored text, and a
// refused write is not evidence the driver's read path is degraded either.
var (driver, client) = await WritableDriverAsync();
var before = driver.GetHealth();
client.WriteOutcome = new MTConnectWriteOutcome(Accepted: false, AgentError: "UNSUPPORTED: no such device");
await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);
var after = driver.GetHealth();
after.LastError.ShouldBe(before.LastError);
after.State.ShouldBe(before.State);
}
[Fact]
public async Task A_transport_failure_maps_to_a_communication_error_without_throwing()
{
var (driver, client) = await WritableDriverAsync();
client.WriteFailure = new HttpRequestException("connection refused");
var results = await driver.WriteAsync([new WriteRequest(PositionRawPath, 42.5)], Ct);
results[0].StatusCode.ShouldBe(BadCommunicationError);
}
// ---- batch contract ----
[Fact]
public async Task Cancellation_fills_the_remaining_slots_and_returns_the_batch()
{
// Never throws, even cancelled: the caller gets one status per request or the node-manager
// cannot tell which writes were attempted.
var (driver, client) = await WritableDriverAsync();
using var cts = new CancellationTokenSource();
await cts.CancelAsync();
var results = await driver.WriteAsync(
[new WriteRequest(PositionRawPath, 1.0), new WriteRequest(PositionRawPath, 2.0)], cts.Token);
results.Count.ShouldBe(2);
results.ShouldAllBe(r => r.StatusCode == BadCommunicationError);
client.Writes.ShouldBeEmpty();
}
[Fact]
public async Task One_bad_request_does_not_fail_the_others_in_the_batch()
{
// Mirrors ReadAsync: failing the whole call would let one stale reference reject every other
// write in the same OPC UA request.
var (driver, client) = await WritableDriverAsync();
var results = await driver.WriteAsync(
[
new WriteRequest(UnknownRawPath, 1.0),
new WriteRequest(ConditionRawPath, "NORMAL"),
new WriteRequest(PositionRawPath, 42.5),
],
Ct);
// Order-preserving, one status per request, each naming its own distinct cause.
results.Count.ShouldBe(3);
results[0].StatusCode.ShouldBe(BadNodeIdUnknown);
results[1].StatusCode.ShouldBe(BadNotWritable);
results[2].StatusCode.ShouldBe(Good);
client.Writes.ShouldHaveSingleItem().DataItemId.ShouldBe(PositionDataItemId);
}
[Fact]
public async Task An_empty_batch_is_answered_with_an_empty_result()
=> (await NewDriver(Opts()).Driver.WriteAsync([], Ct)).ShouldBeEmpty();
[Fact]
public async Task WriteAsync_rejects_a_null_batch()
=> await Should.ThrowAsync<ArgumentNullException>(
async () => await NewDriver(Opts()).Driver.WriteAsync(null!, Ct));
}