UA-.NETStandard/Tests/Opc.Ua.Client.Tests/Session/BrowserTests.cs

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using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Moq;
using NUnit.Framework;
using Opc.Ua.Client.TestFramework;
using Opc.Ua.Tests;

namespace Opc.Ua.Client.Tests
{
    /// <summary>
    /// Tests for <see cref="Browser"/> continuation point handling.
    /// Verifies that null and empty ContinuationPoints are not treated
    /// as valid continuation points per OPC 10000-4 Section 7.9.
    /// </summary>
    [TestFixture]
    [Category("Client")]
    [Category("Browser")]
    [SetCulture("en-us")]
    [SetUICulture("en-us")]
    public sealed class BrowserTests
    {
        /// <summary>
        /// When the server returns a default (null) ContinuationPoint,
        /// BrowseNext must not be called.
        /// </summary>
        [Test]
        public async Task BrowseAsyncWithNullContinuationPointDoesNotCallBrowseNext()
        {
            using var session = SessionMock.Create();
            ReferenceDescription expectedRef = CreateReferenceDescription("Object1");

            session.Channel
                .Setup(c => c.SendRequestAsync(
                    It.IsAny<BrowseRequest>(),
                    It.IsAny<CancellationToken>()))
                .Returns(new ValueTask<IServiceResponse>(new BrowseResponse
                {
                    Results =
                    [
                        new BrowseResult
                        {
                            StatusCode = StatusCodes.Good,
                            ContinuationPoint = default,
                            References = [expectedRef]
                        }
                    ],
                    DiagnosticInfos = []
                }));

            var browser = new Browser(session) { ContinueUntilDone = true };

            // Act
            ArrayOf<ReferenceDescription> result = await browser.BrowseAsync(
                ObjectIds.ObjectsFolder).ConfigureAwait(false);

            // Assert
            Assert.That(result.Count, Is.EqualTo(1));
            Assert.That(result[0].BrowseName, Is.EqualTo(expectedRef.BrowseName));

            session.Channel.Verify(
                c => c.SendRequestAsync(
                    It.IsAny<BrowseNextRequest>(),
                    It.IsAny<CancellationToken>()),
                Times.Never,
                "BrowseNext must not be called when ContinuationPoint is null.");
        }

        /// <summary>
        /// When the server returns an empty (zero-length) ContinuationPoint,
        /// BrowseNext must not be called.
        /// </summary>
        [Test]
        public async Task BrowseAsyncWithEmptyContinuationPointDoesNotCallBrowseNext()
        {
            using var session = SessionMock.Create();
            ReferenceDescription expectedRef = CreateReferenceDescription("Object1");

            session.Channel
                .Setup(c => c.SendRequestAsync(
                    It.IsAny<BrowseRequest>(),
                    It.IsAny<CancellationToken>()))
                .Returns(new ValueTask<IServiceResponse>(new BrowseResponse
                {
                    Results =
                    [
                        new BrowseResult
                        {
                            StatusCode = StatusCodes.Good,
                            ContinuationPoint = ByteString.Empty,
                            References = [expectedRef]
                        }
                    ],
                    DiagnosticInfos = []
                }));

            var browser = new Browser(session) { ContinueUntilDone = true };

            // Act
            ArrayOf<ReferenceDescription> result = await browser.BrowseAsync(
                ObjectIds.ObjectsFolder).ConfigureAwait(false);

            // Assert
            Assert.That(result.Count, Is.EqualTo(1));
            Assert.That(result[0].BrowseName, Is.EqualTo(expectedRef.BrowseName));

            session.Channel.Verify(
                c => c.SendRequestAsync(
                    It.IsAny<BrowseNextRequest>(),
                    It.IsAny<CancellationToken>()),
                Times.Never,
                "BrowseNext must not be called when ContinuationPoint is empty.");
        }

        /// <summary>
        /// When the server returns a valid ContinuationPoint, BrowseNext
        /// must be called to retrieve the remaining references.
        /// </summary>
        [Test]
        public async Task BrowseAsyncWithValidContinuationPointCallsBrowseNext()
        {
            using var session = SessionMock.Create();
            ReferenceDescription firstRef = CreateReferenceDescription("Object1");
            ReferenceDescription secondRef = CreateReferenceDescription("Object2");

            session.Channel
                .Setup(c => c.SendRequestAsync(
                    It.IsAny<BrowseRequest>(),
                    It.IsAny<CancellationToken>()))
                .Returns(new ValueTask<IServiceResponse>(new BrowseResponse
                {
                    Results =
                    [
                        new BrowseResult
                        {
                            StatusCode = StatusCodes.Good,
                            ContinuationPoint = new ByteString(new byte[] { 0x01, 0x02 }),
                            References = [firstRef]
                        }
                    ],
                    DiagnosticInfos = []
                }));

            session.Channel
                .Setup(c => c.SendRequestAsync(
                    It.IsAny<BrowseNextRequest>(),
                    It.IsAny<CancellationToken>()))
                .Returns(new ValueTask<IServiceResponse>(new BrowseNextResponse
                {
                    Results =
                    [
                        new BrowseResult
                        {
                            StatusCode = StatusCodes.Good,
                            ContinuationPoint = default,
                            References = [secondRef]
                        }
                    ],
                    DiagnosticInfos = []
                }));

            var browser = new Browser(session) { ContinueUntilDone = true };

            // Act
            ArrayOf<ReferenceDescription> result = await browser.BrowseAsync(
                ObjectIds.ObjectsFolder).ConfigureAwait(false);

            // Assert
            Assert.That(result.Count, Is.EqualTo(2));
            Assert.That(result[0].BrowseName, Is.EqualTo(firstRef.BrowseName));
            Assert.That(result[1].BrowseName, Is.EqualTo(secondRef.BrowseName));

            session.Channel.Verify(
                c => c.SendRequestAsync(
                    It.IsAny<BrowseNextRequest>(),
                    It.IsAny<CancellationToken>()),
                Times.Once,
                "BrowseNext must be called exactly once for a valid ContinuationPoint.");
        }

        /// <summary>
        /// BrowseStreamAsync yields each result as it arrives and does
        /// not call BrowseNext when ContinuationPoint is null/empty.
        /// </summary>
        [Test]
        public async Task BrowseStreamAsyncWithoutContinuationDoesNotCallBrowseNext()
        {
            using var session = SessionMock.Create();
            ReferenceDescription firstRef = CreateReferenceDescription("Object1");
            ReferenceDescription secondRef = CreateReferenceDescription("Object2");

            session.Channel
                .Setup(c => c.SendRequestAsync(
                    It.IsAny<BrowseRequest>(),
                    It.IsAny<CancellationToken>()))
                .Returns(new ValueTask<IServiceResponse>(new BrowseResponse
                {
                    Results =
                    [
                        new BrowseResult
                        {
                            StatusCode = StatusCodes.Good,
                            ContinuationPoint = default,
                            References = [firstRef]
                        },
                        new BrowseResult
                        {
                            StatusCode = StatusCodes.Good,
                            ContinuationPoint = ByteString.Empty,
                            References = [secondRef]
                        }
                    ],
                    DiagnosticInfos = []
                }));

            var browser = new Browser(session);
            ArrayOf<BrowseDescription> nodesToBrowse =
            [
                new BrowseDescription { NodeId = ObjectIds.ObjectsFolder },
                new BrowseDescription { NodeId = ObjectIds.RootFolder }
            ];

            // Act
            var results = new List<BrowseResult>();
            await foreach (BrowseResult result in browser.BrowseStreamAsync(
                null, null, nodesToBrowse, default).ConfigureAwait(false))
            {
                results.Add(result);
            }

            // Assert
            Assert.That(results, Has.Count.EqualTo(2));
            Assert.That(results[0].References[0].BrowseName, Is.EqualTo(firstRef.BrowseName));
            Assert.That(results[1].References[0].BrowseName, Is.EqualTo(secondRef.BrowseName));

            session.Channel.Verify(
                c => c.SendRequestAsync(
                    It.IsAny<BrowseNextRequest>(),
                    It.IsAny<CancellationToken>()),
                Times.Never,
                "BrowseNext must not be called when no ContinuationPoint is set.");
        }

        /// <summary>
        /// BrowseStreamAsync follows continuation points and yields the
        /// follow-up results.
        /// </summary>
        [Test]
        public async Task BrowseStreamAsyncFollowsContinuationPoints()
        {
            using var session = SessionMock.Create();
            ReferenceDescription firstRef = CreateReferenceDescription("Object1");
            ReferenceDescription secondRef = CreateReferenceDescription("Object2");

            session.Channel
                .Setup(c => c.SendRequestAsync(
                    It.IsAny<BrowseRequest>(),
                    It.IsAny<CancellationToken>()))
                .Returns(new ValueTask<IServiceResponse>(new BrowseResponse
                {
                    Results =
                    [
                        new BrowseResult
                        {
                            StatusCode = StatusCodes.Good,
                            ContinuationPoint = new ByteString(new byte[] { 0x01, 0x02 }),
                            References = [firstRef]
                        }
                    ],
                    DiagnosticInfos = []
                }));

            session.Channel
                .Setup(c => c.SendRequestAsync(
                    It.IsAny<BrowseNextRequest>(),
                    It.IsAny<CancellationToken>()))
                .Returns(new ValueTask<IServiceResponse>(new BrowseNextResponse
                {
                    Results =
                    [
                        new BrowseResult
                        {
                            StatusCode = StatusCodes.Good,
                            ContinuationPoint = default,
                            References = [secondRef]
                        }
                    ],
                    DiagnosticInfos = []
                }));

            var browser = new Browser(session);
            ArrayOf<BrowseDescription> nodesToBrowse =
            [
                new BrowseDescription { NodeId = ObjectIds.ObjectsFolder }
            ];

            // Act
            var results = new List<BrowseResult>();
            await foreach (BrowseResult result in browser.BrowseStreamAsync(
                null, null, nodesToBrowse, default).ConfigureAwait(false))
            {
                results.Add(result);
            }

            // Assert — first the initial page, then the follow-up.
            Assert.That(results, Has.Count.EqualTo(2));
            Assert.That(results[0].References[0].BrowseName, Is.EqualTo(firstRef.BrowseName));
            Assert.That(results[1].References[0].BrowseName, Is.EqualTo(secondRef.BrowseName));

            session.Channel.Verify(
                c => c.SendRequestAsync(
                    It.IsAny<BrowseNextRequest>(),
                    It.IsAny<CancellationToken>()),
                Times.Once);
        }

        /// <summary>
        /// BrowseStreamAsync throws ServiceResultException when the
        /// browser has no attached session.
        /// </summary>
        [Test]
        public void BrowseStreamAsyncThrowsWhenNotAttached()
        {
            ITelemetryContext telemetry = NUnitTelemetryContext.Create();
            var browser = new Browser(telemetry);
            ArrayOf<BrowseDescription> nodesToBrowse =
            [
                new BrowseDescription { NodeId = ObjectIds.ObjectsFolder }
            ];

            Assert.That(
                async () =>
                {
                    await foreach (BrowseResult _ in browser.BrowseStreamAsync(
                        null, null, nodesToBrowse, default).ConfigureAwait(false))
                    {
                    }
                },
                Throws.TypeOf<ServiceResultException>()
                    .With.Property("StatusCode")
                    .EqualTo(StatusCodes.BadServerNotConnected));
        }

        private static ReferenceDescription CreateReferenceDescription(string name)
        {
            return new ReferenceDescription
            {
                NodeId = new NodeId(name, 0),
                BrowseName = new QualifiedName(name),
                DisplayName = new LocalizedText(name),
                NodeClass = NodeClass.Object,
                TypeDefinition = ObjectTypeIds.BaseObjectType
            };
        }
    }
}