UA-.NETStandard/tests/Opc.Ua.PubSub.Tests/Groups/DataSetReaderTimeoutWatcherTests.cs

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using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.Extensions.Time.Testing;
using NUnit.Framework;
using Opc.Ua.PubSub.DataSets;
using Opc.Ua.PubSub.Diagnostics;
using Opc.Ua.PubSub.Encoding;
using Opc.Ua.PubSub.Groups;
using Opc.Ua.Tests;

namespace Opc.Ua.PubSub.Tests.Groups
{
    /// <summary>
    /// Validates the deterministic timeout behaviour of
    /// <see cref="DataSetReaderTimeoutWatcher"/>: when a reader does not
    /// see a dispatch within its <c>MessageReceiveTimeout</c> the watcher
    /// must increment the <c>MessageReceiveTimeouts</c> diagnostics
    /// counter, record a <c>BadTimeout</c> error and fault the reader's
    /// state machine.
    /// </summary>
    /// <remarks>
    /// Covers
    /// <see href="https://reference.opcfoundation.org/specs/OPC-10000-14/v1.05.06/6.2.9.6">
    /// Part 14 §6.2.9.6 DataSetReader status</see> and
    /// <see href="https://reference.opcfoundation.org/specs/OPC-10000-14/v1.05.06/9.1.6.3">
    /// §9.1.6.3 ReaderGroup state transitions</see>.
    /// </remarks>
    [TestFixture]
    [TestSpec("6.2.9.6", Summary = "MessageReceiveTimeout fault path")]
    [TestSpec("9.1.6.3")]
    public class DataSetReaderTimeoutWatcherTests
    {
        [Test]
        public async Task PollOnceAsync_FaultsReaderAndIncrementsCounterAsync()
        {
            var clock = new FakeTimeProvider(
                new DateTimeOffset(2026, 1, 1, 0, 0, 0, TimeSpan.Zero));
            DataSetReader reader = BuildReader(clock, timeoutMs: 500);
            var diagnostics = new PubSubDiagnostics(
                PubSubDiagnosticsLevel.High, clock);

            await using var watcher = new DataSetReaderTimeoutWatcher(
                [reader],
                new NoOpScheduler(),
                diagnostics,
                NUnitTelemetryContext.Create());

            // No time elapsed — reader stays operational, counter stays at 0.
            await watcher.PollOnceAsync().ConfigureAwait(false);
            Assert.That(reader.State.State, Is.EqualTo(PubSubState.Operational));
            Assert.That(
                diagnostics.Read(PubSubDiagnosticsCounterKind.MessageReceiveTimeouts),
                Is.Zero);

            // Advance the clock past the receive timeout.
            clock.Advance(TimeSpan.FromMilliseconds(750));
            await watcher.PollOnceAsync().ConfigureAwait(false);

            Assert.Multiple(() =>
            {
                Assert.That(reader.State.State, Is.EqualTo(PubSubState.Error));
                Assert.That(reader.State.StatusCode, Is.EqualTo(StatusCodes.BadTimeout));
                Assert.That(
                    diagnostics.Read(PubSubDiagnosticsCounterKind.MessageReceiveTimeouts),
                    Is.EqualTo(1L));
            });

            // Second poll after the reader is already in Error must not
            // re-increment the counter (spec: one fault per timeout).
            await watcher.PollOnceAsync().ConfigureAwait(false);
            Assert.That(
                diagnostics.Read(PubSubDiagnosticsCounterKind.MessageReceiveTimeouts),
                Is.EqualTo(1L));
        }

        [Test]
        public async Task PollOnceAsync_DoesNotFaultBeforeTimeoutAsync()
        {
            var clock = new FakeTimeProvider(
                new DateTimeOffset(2026, 1, 1, 0, 0, 0, TimeSpan.Zero));
            DataSetReader reader = BuildReader(clock, timeoutMs: 5000);
            var diagnostics = new PubSubDiagnostics(
                PubSubDiagnosticsLevel.High, clock);

            await using var watcher = new DataSetReaderTimeoutWatcher(
                [reader],
                new NoOpScheduler(),
                diagnostics,
                NUnitTelemetryContext.Create());

            clock.Advance(TimeSpan.FromMilliseconds(250));
            await watcher.PollOnceAsync().ConfigureAwait(false);

            Assert.Multiple(() =>
            {
                Assert.That(reader.State.State, Is.EqualTo(PubSubState.Operational));
                Assert.That(
                    diagnostics.Read(PubSubDiagnosticsCounterKind.MessageReceiveTimeouts),
                    Is.Zero);
            });
        }

        private static DataSetReader BuildReader(TimeProvider clock, int timeoutMs)
        {
            var config = new DataSetReaderDataType
            {
                Name = "reader",
                DataSetWriterId = 1,
                WriterGroupId = 1,
                MessageReceiveTimeout = timeoutMs
            };
            var reader = new DataSetReader(
                config,
                NullSink.Instance,
                NUnitTelemetryContext.Create(),
                clock);
            _ = reader.State.TryEnable();
            _ = reader.State.TryMarkOperational();
            return reader;
        }

        private sealed class NullSink : ISubscribedDataSetSink
        {
            public static NullSink Instance { get; } = new();

            public ValueTask WriteAsync(
                IReadOnlyList<DataSetField> fields,
                System.Threading.CancellationToken cancellationToken = default)
            {
                return default;
            }
        }

        private sealed class NoOpScheduler : PubSub.Scheduling.IPubSubScheduler
        {
            public ValueTask<IAsyncDisposable> ScheduleAsync(
                PubSub.Scheduling.PubSubSchedule schedule,
                Func<System.Threading.CancellationToken, ValueTask> action,
                System.Threading.CancellationToken cancellationToken = default)
            {
                return new ValueTask<IAsyncDisposable>(NoOpHandle.Instance);
            }

            private sealed class NoOpHandle : IAsyncDisposable
            {
                public static NoOpHandle Instance { get; } = new();

                public ValueTask DisposeAsync()
                {
                    return default;
                }
            }
        }
    }
}