ScadaBridge/tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Actors/DataConnectionProbeSeedTests.cs

using Akka.Actor;
using Akka.TestKit.Xunit2;
using NSubstitute;
using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Protocol;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.DataConnection;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Enums;
using ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Actors;
using ZB.MOM.WW.ScadaBridge.HealthMonitoring;

namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests.Actors;

/// <summary>
/// The tag-resolution PROBE path did not seed the tags it
/// resolved.
///
/// <para>
/// <b>The gap this pins.</b> Both other subscribe paths read each newly advised tag's current
/// value and deliver it (<c>HandleSubscribe</c> carries the seeds back on <c>SubscribeCompleted</c>;
/// <c>ReSubscribeAll</c> re-seeds after a reconnect), because a fresh advise only produces a value
/// on the source's next CHANGE. <c>HandleRetryTagResolution</c> did not. OPC UA masks that with an
/// initial data-change notification on subscription creation, but an MxGateway advise can
/// legitimately return <c>VT_EMPTY</c> — so a STATIC tag that resolved LATE (device still booting,
/// item created after deployment) had no value path at all and its attribute stayed Uncertain for
/// the life of the connection.
/// </para>
/// </summary>
[Collection("DataConnectionManagerActor")]
public class DataConnectionProbeSeedTests : TestKit
{
    private const string Tag = "plant/static/setpoint";

    private readonly ISiteHealthCollector _health = Substitute.For<ISiteHealthCollector>();
    private readonly IDataConnectionFactory _factory = Substitute.For<IDataConnectionFactory>();

    private readonly DataConnectionOptions _options = new()
    {
        ReconnectInterval = TimeSpan.FromMilliseconds(100),
        TagResolutionRetryInterval = TimeSpan.FromMilliseconds(150),
        WriteTimeout = TimeSpan.FromSeconds(5),
        SeedReadMaxAttempts = 1,
        SeedReadRetryDelay = TimeSpan.FromMilliseconds(10)
    };

    private IActorRef CreateConnectionActor(string name, IDataConnection adapter) =>
        Sys.ActorOf(Props.Create(() =>
            new DataConnectionActor(name, adapter, _options, _health, _factory, "OpcUa")), name);

    private bool HasEnteredConnectedState(string connectionName) =>
        _health.ReceivedCalls().Any(c =>
            c.GetMethodInfo().Name == nameof(ISiteHealthCollector.UpdateConnectionHealth) &&
            c.GetArguments() is [string name, ConnectionHealth.Connected, ..] &&
            name == connectionName);

    /// <summary>
    /// A tag that fails to resolve on the initial subscribe, resolves on the first probe round,
    /// and then never changes again must still reach its subscriber with a Good value.
    ///
    /// <para>
    /// The adapter here models exactly the MxGateway shape the finding calls out: the advise
    /// succeeds on the retry but the subscription callback is NEVER invoked (a <c>VT_EMPTY</c>
    /// advise on a static item), so the seed read is the tag's only possible value source.
    /// </para>
    ///
    /// <para><b>Fails before the fix:</b> the probe resolved the tag and stopped there — the
    /// subscriber received only the Bad-quality resolution-failure push from the initial
    /// subscribe, and this fish for a Good value timed out.</para>
    /// </summary>
    [Fact]
    public void ProbeResolvedTag_IsSeeded_SoAStaticTagLeavesUncertain()
    {
        const string name = "probe-seed";
        var subscribeCalls = 0;

        var adapter = Substitute.For<IDataConnection>();
        adapter.ConnectAsync(Arg.Any<IDictionary<string, string>>(), Arg.Any<CancellationToken>())
            .Returns(Task.CompletedTask);
        adapter.Status.Returns(ConnectionHealth.Connected);
        adapter.SubscribeAsync(Tag, Arg.Any<SubscriptionCallback>(), Arg.Any<CancellationToken>())
            .Returns(_ => Interlocked.Increment(ref subscribeCalls) == 1
                // Initial subscribe: the device is still booting — a genuine (non
                // connection-level) resolution failure, so the tag lands in _unresolvedTags.
                ? Task.FromException<string>(new KeyNotFoundException("node not found yet"))
                // Probe round: the advise succeeds. The callback is deliberately never invoked.
                : Task.FromResult("sub-1"));
        adapter.ReadAsync(Tag, Arg.Any<CancellationToken>())
            .Returns(new ReadResult(true, new TagValue(42, QualityCode.Good, DateTimeOffset.UtcNow), null));

        var actor = CreateConnectionActor(name, adapter);
        AwaitCondition(() => HasEnteredConnectedState(name),
            TimeSpan.FromSeconds(5), TimeSpan.FromMilliseconds(10));

        var subscriber = CreateTestProbe();
        subscriber.Send(actor, new SubscribeTagsRequest("c1", "inst1", name, [Tag], DateTimeOffset.UtcNow));

        // The initial subscribe fails: Bad-quality push, then the ack.
        subscriber.FishForMessage<SubscribeTagsResponse>(_ => true, TimeSpan.FromSeconds(5));

        // The probe round resolves the tag; the seed read is the only thing that can now
        // deliver a value, because the advise callback never fires for this static item.
        var seeded = subscriber.FishForMessage<TagValueUpdate>(
            m => m.TagPath == Tag && m.Quality == QualityCode.Good, TimeSpan.FromSeconds(10));

        Assert.Equal(42, seeded.Value);
        Assert.True(Volatile.Read(ref subscribeCalls) >= 2, "the probe round must have re-subscribed the tag");
    }
}