mxaccessgw/clients/dotnet/MxGateway.Client.Tests/MxGatewayClientCliTests.cs

using Google.Protobuf.WellKnownTypes;
using MxGateway.Client.Cli;
using MxGateway.Contracts.Proto;
using MxGateway.Contracts.Proto.Galaxy;

namespace MxGateway.Client.Tests;

/// <summary>Tests for the CLI command interface.</summary>
public sealed class MxGatewayClientCliTests
{
    /// <summary>Verifies that the version command prints compiled protocol versions.</summary>
    [Fact]
    public void Run_Version_PrintsCompiledProtocolVersions()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();

        var exitCode = MxGatewayClientCli.Run(["version"], output, error);

        Assert.Equal(0, exitCode);
        Assert.Contains("gateway-protocol=3", output.ToString());
        Assert.Contains("worker-protocol=1", output.ToString());
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that the version command with --json flag prints JSON protocol versions.</summary>
    [Fact]
    public async Task RunAsync_VersionJson_PrintsJsonProtocolVersions()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();

        int exitCode = await MxGatewayClientCli.RunAsync(["version", "--json"], output, error);

        Assert.Equal(0, exitCode);
        Assert.Contains("\"gatewayProtocolVersion\":3", output.ToString());
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that the write command builds a write request and prints JSON reply.</summary>
    [Fact]
    public async Task RunAsync_Write_BuildsWriteCommandAndPrintsJsonReply()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new();
        fakeClient.InvokeReplies.Enqueue(new MxCommandReply
        {
            SessionId = "session-fixture",
            Kind = MxCommandKind.Write,
            ProtocolStatus = new ProtocolStatus { Code = ProtocolStatusCode.Ok },
        });

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "write",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
                "--session-id",
                "session-fixture",
                "--server-handle",
                "12",
                "--item-handle",
                "34",
                "--type",
                "int32",
                "--value",
                "123",
                "--json",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(0, exitCode);
        MxCommandRequest request = Assert.Single(fakeClient.InvokeRequests);
        Assert.Equal(MxCommandKind.Write, request.Command.Kind);
        Assert.Equal(123, request.Command.Write.Value.Int32Value);
        Assert.Contains("MX_COMMAND_KIND_WRITE", output.ToString());
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that error output redacts sensitive API key values.</summary>
    [Fact]
    public async Task RunAsync_ErrorOutput_RedactsApiKey()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "open-session",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "secret-api-key",
            ],
            output,
            error,
            _ => throw new InvalidOperationException("boom secret-api-key"));

        Assert.Equal(1, exitCode);
        Assert.DoesNotContain("secret-api-key", error.ToString());
        Assert.Contains("[redacted]", error.ToString());
    }

    /// <summary>
    /// Verifies that error output redacts the API key even when it was sourced from
    /// the <c>--api-key-env</c> environment variable rather than passed via
    /// <c>--api-key</c> — the documented default credential path.
    /// </summary>
    [Fact]
    public async Task RunAsync_ErrorOutput_RedactsApiKey_WhenSourcedFromEnvironmentVariable()
    {
        const string environmentVariableName = "MXGATEWAY_TEST_API_KEY_REDACT";
        using var output = new StringWriter();
        using var error = new StringWriter();

        Environment.SetEnvironmentVariable(environmentVariableName, "env-secret-api-key");
        try
        {
            int exitCode = await MxGatewayClientCli.RunAsync(
                [
                    "open-session",
                    "--endpoint",
                    "http://localhost:5000",
                    "--api-key-env",
                    environmentVariableName,
                ],
                output,
                error,
                _ => throw new InvalidOperationException("boom env-secret-api-key"));

            Assert.Equal(1, exitCode);
            Assert.DoesNotContain("env-secret-api-key", error.ToString());
            Assert.Contains("[redacted]", error.ToString());
        }
        finally
        {
            Environment.SetEnvironmentVariable(environmentVariableName, null);
        }
    }

    /// <summary>Verifies that stream-events with max-events limit stops output in non-JSON format.</summary>
    [Fact]
    public async Task RunAsync_StreamEvents_WithMaxEventsStopsNonJsonOutput()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new();
        fakeClient.Events.Add(new MxEvent
        {
            SessionId = "session-fixture",
            Family = MxEventFamily.OnDataChange,
            WorkerSequence = 1,
        });
        fakeClient.Events.Add(new MxEvent
        {
            SessionId = "session-fixture",
            Family = MxEventFamily.OnWriteComplete,
            WorkerSequence = 2,
        });

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "stream-events",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
                "--session-id",
                "session-fixture",
                "--max-events",
                "1",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(0, exitCode);
        Assert.Contains("workerSequence", output.ToString());
        Assert.DoesNotContain("ON_WRITE_COMPLETE", output.ToString());
    }

    /// <summary>
    ///     Client.Dotnet-017 regression: a finite-window event collector
    ///     (<c>stream-events --timeout</c>) must exit 0 and emit the events
    ///     that arrived before the timeout fired, instead of propagating the
    ///     timeout-driven <see cref="OperationCanceledException"/> as an
    ///     unhandled exception (exit code -532462766). The fix wraps the
    ///     <c>await foreach</c> in a token-aware catch so the cancellation
    ///     ends the foreach gracefully; the aggregated JSON output still runs.
    /// </summary>
    [Fact]
    public async Task RunAsync_StreamEvents_WhenTimeoutFiresAfterEvents_EmitsCollectedEventsAndExitsZero()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new();
        fakeClient.Events.Add(new MxEvent
        {
            SessionId = "session-fixture",
            Family = MxEventFamily.OnDataChange,
            WorkerSequence = 1,
        });
        fakeClient.Events.Add(new MxEvent
        {
            SessionId = "session-fixture",
            Family = MxEventFamily.OnDataChange,
            WorkerSequence = 2,
        });
        // Park forever after yielding the configured events so the CLI's
        // --timeout drives the cancellation path.
        fakeClient.StreamHangAfterEvents = async token =>
        {
            await Task.Delay(Timeout.InfiniteTimeSpan, token).ConfigureAwait(false);
        };

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "stream-events",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
                "--session-id",
                "session-fixture",
                "--json",
                "--max-events",
                "200",
                "--timeout",
                "1s",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(0, exitCode);
        string json = output.ToString();
        // Aggregate JSON output must run even though the foreach exited via
        // cancellation, and it must contain both events that arrived first.
        Assert.Contains("\"events\"", json);
        Assert.Contains("\"workerSequence\":\"1\"", json);
        Assert.Contains("\"workerSequence\":\"2\"", json);
        Assert.Equal(string.Empty, error.ToString());
    }


    /// <summary>Verifies that stream-alarms with --max-events stops output and distinguishes payload cases.</summary>
    [Fact]
    public async Task RunAsync_StreamAlarms_WithMaxEventsStopsAndDistinguishesPayloadCases()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new();
        fakeClient.AlarmFeedMessages.Add(new AlarmFeedMessage
        {
            ActiveAlarm = new ActiveAlarmSnapshot { AlarmFullReference = "Tank01.Level.HiHi" },
        });
        fakeClient.AlarmFeedMessages.Add(new AlarmFeedMessage { SnapshotComplete = true });

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "stream-alarms",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
                "--filter-prefix",
                "Tank01",
                "--max-events",
                "1",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(0, exitCode);
        StreamAlarmsRequest request = Assert.Single(fakeClient.StreamAlarmsRequests);
        Assert.Equal("Tank01", request.AlarmFilterPrefix);
        string text = output.ToString();
        Assert.Contains("active-alarm", text);
        Assert.Contains("Tank01.Level.HiHi", text);
        Assert.DoesNotContain("snapshot-complete", text);
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that acknowledge-alarm builds a request and prints the JSON reply.</summary>
    [Fact]
    public async Task RunAsync_AcknowledgeAlarm_BuildsRequestAndPrintsJsonReply()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new();
        fakeClient.AcknowledgeAlarmReplies.Enqueue(new AcknowledgeAlarmReply
        {
            CorrelationId = "ack-fixture",
            ProtocolStatus = new ProtocolStatus { Code = ProtocolStatusCode.Ok },
            Hresult = 0,
        });

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "acknowledge-alarm",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
                "--reference",
                "Tank01.Level.HiHi",
                "--comment",
                "ack from cli",
                "--operator",
                "operator1",
                "--json",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(0, exitCode);
        AcknowledgeAlarmRequest request = Assert.Single(fakeClient.AcknowledgeAlarmRequests);
        Assert.Equal("Tank01.Level.HiHi", request.AlarmFullReference);
        Assert.Equal("ack from cli", request.Comment);
        Assert.Equal("operator1", request.OperatorUser);
        Assert.Contains("ack-fixture", output.ToString());
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that smoke command closes opened session when a command fails.</summary>
    [Fact]
    public async Task RunAsync_Smoke_WhenCommandFails_ClosesOpenedSession()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new()
        {
            InvokeFailure = new InvalidOperationException("register failed"),
        };

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "smoke",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
                "--item",
                "Area001.Pump001.Speed",
                "--json",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(1, exitCode);
        CloseSessionRequest closeRequest = Assert.Single(fakeClient.CloseSessionRequests);
        Assert.Equal("session-fixture", closeRequest.SessionId);
    }

    /// <summary>Verifies that galaxy-test-connection command prints JSON reply.</summary>
    [Fact]
    public async Task RunAsync_GalaxyTestConnection_PrintsJsonReply()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new()
        {
            GalaxyTestConnectionReply = new TestConnectionReply { Ok = true },
        };

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "galaxy-test-connection",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
                "--json",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(0, exitCode);
        Assert.Single(fakeClient.GalaxyTestConnectionRequests);
        Assert.Contains("\"ok\": true", output.ToString());
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that galaxy-discover command prints hierarchy summary.</summary>
    [Fact]
    public async Task RunAsync_GalaxyDiscover_PrintsHierarchySummary()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new();
        fakeClient.GalaxyDiscoverHierarchyReplies.Enqueue(new DiscoverHierarchyReply
        {
            NextPageToken = "7:1",
            TotalObjectCount = 2,
            Objects =
            {
                new GalaxyObject
                {
                    GobjectId = 7,
                    TagName = "DelmiaReceiver_001",
                    ContainedName = "DelmiaReceiver",
                    ParentGobjectId = 1,
                    Attributes =
                    {
                        new GalaxyAttribute
                        {
                            AttributeName = "DownloadPath",
                            FullTagReference = "DelmiaReceiver_001.DownloadPath",
                        },
                    },
                },
            },
        });
        fakeClient.GalaxyDiscoverHierarchyReplies.Enqueue(new DiscoverHierarchyReply
        {
            TotalObjectCount = 2,
            Objects =
            {
                new GalaxyObject
                {
                    GobjectId = 8,
                    TagName = "DelmiaReceiver_002",
                    ContainedName = "DelmiaReceiver",
                    ParentGobjectId = 1,
                },
            },
        });

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "galaxy-discover",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(0, exitCode);
        Assert.Equal(2, fakeClient.GalaxyDiscoverHierarchyRequests.Count);
        Assert.Equal(5000, fakeClient.GalaxyDiscoverHierarchyRequests[0].PageSize);
        Assert.Equal("", fakeClient.GalaxyDiscoverHierarchyRequests[0].PageToken);
        Assert.Equal("7:1", fakeClient.GalaxyDiscoverHierarchyRequests[1].PageToken);
        string text = output.ToString();
        Assert.Contains("objects=2", text);
        Assert.Contains("DelmiaReceiver_001", text);
        Assert.Contains("DelmiaReceiver_002", text);
        Assert.Contains("attributes=1", text);
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that galaxy-watch command prints text output for deploy events.</summary>
    [Fact]
    public async Task RunAsync_GalaxyWatch_PrintsTextOutputForEvents()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new();
        DateTime deploy = new(2026, 4, 28, 14, 30, 0, DateTimeKind.Utc);
        fakeClient.GalaxyDeployEvents.Add(new DeployEvent
        {
            Sequence = 1,
            ObservedAt = Timestamp.FromDateTime(deploy),
            TimeOfLastDeploy = Timestamp.FromDateTime(deploy),
            TimeOfLastDeployPresent = true,
            ObjectCount = 5,
            AttributeCount = 17,
        });
        fakeClient.GalaxyDeployEvents.Add(new DeployEvent
        {
            Sequence = 2,
            ObservedAt = Timestamp.FromDateTime(deploy.AddSeconds(30)),
            TimeOfLastDeploy = Timestamp.FromDateTime(deploy.AddSeconds(30)),
            TimeOfLastDeployPresent = true,
            ObjectCount = 6,
            AttributeCount = 18,
        });

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "galaxy-watch",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
                "--last-seen-deploy-time",
                "2026-04-28T14:00:00Z",
                "--max-events",
                "2",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(0, exitCode);
        WatchDeployEventsRequest request = Assert.Single(fakeClient.GalaxyWatchDeployEventsRequests);
        Assert.NotNull(request.LastSeenDeployTime);
        string text = output.ToString();
        Assert.Contains("sequence=1", text);
        Assert.Contains("sequence=2", text);
        Assert.Contains("objects=5", text);
        Assert.Contains("attributes=18", text);
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that galaxy-watch with --json emits one JSON object per event.</summary>
    [Fact]
    public async Task RunAsync_GalaxyWatch_JsonEmitsOneObjectPerEvent()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        FakeCliClient fakeClient = new();
        fakeClient.GalaxyDeployEvents.Add(new DeployEvent
        {
            Sequence = 42,
            ObjectCount = 99,
            AttributeCount = 1024,
        });

        int exitCode = await MxGatewayClientCli.RunAsync(
            [
                "galaxy-watch",
                "--endpoint",
                "http://localhost:5000",
                "--api-key",
                "test-api-key",
                "--max-events",
                "1",
                "--json",
            ],
            output,
            error,
            _ => fakeClient);

        Assert.Equal(0, exitCode);
        string text = output.ToString();
        Assert.Contains("\"sequence\": \"42\"", text);
        Assert.Contains("\"objectCount\": 99", text);
    }

    /// <summary>Verifies that batch mode executes a single no-gateway command and writes the EOR sentinel.</summary>
    [Fact]
    public async Task RunAsync_Batch_SingleVersionCommand_WritesOutputAndEorSentinel()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        using var stdin = new StringReader("version --json\n");

        int exitCode = await MxGatewayClientCli.RunAsync(
            ["batch"],
            output,
            error,
            clientFactory: null,
            standardInput: stdin);

        Assert.Equal(0, exitCode);
        string text = output.ToString();
        Assert.Contains("\"gatewayProtocolVersion\"", text);
        Assert.Contains("__MXGW_BATCH_EOR__", text);
        // Sentinel must appear after the output, not before.
        int outputIdx = text.IndexOf("gatewayProtocolVersion", StringComparison.Ordinal);
        int eorIdx = text.IndexOf("__MXGW_BATCH_EOR__", StringComparison.Ordinal);
        Assert.True(outputIdx < eorIdx, "EOR sentinel must follow command output.");
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that batch mode processes two commands sequentially and writes two EOR sentinels.</summary>
    [Fact]
    public async Task RunAsync_Batch_TwoVersionCommands_WritesTwoEorSentinels()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        // Two commands followed by EOF (end of string).
        using var stdin = new StringReader("version\nversion --json\n");

        int exitCode = await MxGatewayClientCli.RunAsync(
            ["batch"],
            output,
            error,
            clientFactory: null,
            standardInput: stdin);

        Assert.Equal(0, exitCode);
        string text = output.ToString();
        int firstEor = text.IndexOf("__MXGW_BATCH_EOR__", StringComparison.Ordinal);
        int secondEor = text.IndexOf("__MXGW_BATCH_EOR__", firstEor + 1, StringComparison.Ordinal);
        Assert.True(firstEor >= 0, "First EOR sentinel must be present.");
        Assert.True(secondEor > firstEor, "Second EOR sentinel must follow first.");
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Verifies that batch mode on EOF (empty stdin) exits 0 immediately without writing any sentinel.</summary>
    [Fact]
    public async Task RunAsync_Batch_EmptyStdin_ExitsZeroWithNoOutput()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        using var stdin = new StringReader(string.Empty);

        int exitCode = await MxGatewayClientCli.RunAsync(
            ["batch"],
            output,
            error,
            clientFactory: null,
            standardInput: stdin);

        Assert.Equal(0, exitCode);
        Assert.Equal(string.Empty, output.ToString());
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>
    ///     Verifies that batch mode continues after a command failure and writes the error JSON
    ///     to stdout (not stderr), followed by the EOR sentinel.
    /// </summary>
    [Fact]
    public async Task RunAsync_Batch_CommandFailure_WritesErrorJsonToStdoutAndContinues()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        // First line: a gateway command with no API key (will fail).
        // Second line: version (will succeed).
        using var stdin = new StringReader("open-session --endpoint http://localhost:5000\nversion --json\n");

        int exitCode = await MxGatewayClientCli.RunAsync(
            ["batch"],
            output,
            error,
            clientFactory: _ => throw new InvalidOperationException("injected failure"),
            standardInput: stdin);

        Assert.Equal(0, exitCode);
        string text = output.ToString();

        // Error record: the error JSON must be on stdout, not stderr.
        Assert.Contains("\"error\"", text);
        Assert.Equal(string.Empty, error.ToString());

        // Both records must be present.
        int firstEor = text.IndexOf("__MXGW_BATCH_EOR__", StringComparison.Ordinal);
        int secondEor = text.IndexOf("__MXGW_BATCH_EOR__", firstEor + 1, StringComparison.Ordinal);
        Assert.True(firstEor >= 0, "EOR after failed command must be present.");
        Assert.True(secondEor > firstEor, "EOR after successful command must follow first EOR.");

        // Second record must contain the version output.
        string afterFirstEor = text[(firstEor + "__MXGW_BATCH_EOR__".Length)..];
        Assert.Contains("\"gatewayProtocolVersion\"", afterFirstEor);
    }

    /// <summary>Verifies that batch mode treats an empty (blank) line as EOF and exits 0.</summary>
    [Fact]
    public async Task RunAsync_Batch_EmptyLine_ExitsZeroAfterPreviousCommands()
    {
        using var output = new StringWriter();
        using var error = new StringWriter();
        // One command, then an empty line (stop signal), then another command that must NOT run.
        using var stdin = new StringReader("version --json\n\nversion --json\n");

        int exitCode = await MxGatewayClientCli.RunAsync(
            ["batch"],
            output,
            error,
            clientFactory: null,
            standardInput: stdin);

        Assert.Equal(0, exitCode);
        string text = output.ToString();
        // Only one EOR sentinel — the second command after the empty line must not execute.
        int firstEor = text.IndexOf("__MXGW_BATCH_EOR__", StringComparison.Ordinal);
        int secondEor = text.IndexOf("__MXGW_BATCH_EOR__", firstEor + 1, StringComparison.Ordinal);
        Assert.True(firstEor >= 0, "One EOR sentinel must be present.");
        Assert.Equal(-1, secondEor);
        Assert.Equal(string.Empty, error.ToString());
    }

    /// <summary>Fake CLI client for testing.</summary>
    private sealed class FakeCliClient : IMxGatewayCliClient
    {
        /// <summary>Queue of invoke replies to return.</summary>
        public Queue<MxCommandReply> InvokeReplies { get; } = new();

        /// <summary>List of received invoke requests.</summary>
        public List<MxCommandRequest> InvokeRequests { get; } = [];

        /// <summary>List of received close session requests.</summary>
        public List<CloseSessionRequest> CloseSessionRequests { get; } = [];

        /// <summary>List of events to yield when streaming.</summary>
        public List<MxEvent> Events { get; } = [];

        /// <summary>Exception to throw on invoke, if any.</summary>
        public Exception? InvokeFailure { get; init; }

        /// <summary>
        ///     When set, after yielding all <see cref="Events"/> the stream
        ///     awaits the provided handle and then throws
        ///     <see cref="OperationCanceledException"/> — used to simulate the
        ///     CLI timeout / Ctrl+C cancellation path (Client.Dotnet-017).
        /// </summary>
        public Func<CancellationToken, Task>? StreamHangAfterEvents { get; set; }

        /// <inheritdoc />
        public ValueTask DisposeAsync()
        {
            return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public Task<OpenSessionReply> OpenSessionAsync(
            OpenSessionRequest request,
            CancellationToken cancellationToken)
        {
            return Task.FromResult(new OpenSessionReply
            {
                SessionId = "session-fixture",
                ProtocolStatus = new ProtocolStatus { Code = ProtocolStatusCode.Ok },
                GatewayProtocolVersion = 1,
                WorkerProtocolVersion = 1,
            });
        }

        /// <inheritdoc />
        public Task<CloseSessionReply> CloseSessionAsync(
            CloseSessionRequest request,
            CancellationToken cancellationToken)
        {
            CloseSessionRequests.Add(request);
            return Task.FromResult(new CloseSessionReply
            {
                SessionId = request.SessionId,
                ProtocolStatus = new ProtocolStatus { Code = ProtocolStatusCode.Ok },
                FinalState = SessionState.Closed,
            });
        }

        /// <inheritdoc />
        public Task<MxCommandReply> InvokeAsync(
            MxCommandRequest request,
            CancellationToken cancellationToken)
        {
            InvokeRequests.Add(request);
            if (InvokeFailure is not null)
            {
                throw InvokeFailure;
            }

            return Task.FromResult(InvokeReplies.Dequeue());
        }

        /// <inheritdoc />
        public async IAsyncEnumerable<MxEvent> StreamEventsAsync(
            StreamEventsRequest request,
            [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken)
        {
            foreach (MxEvent gatewayEvent in Events)
            {
                cancellationToken.ThrowIfCancellationRequested();
                await Task.Yield();
                yield return gatewayEvent;
            }

            if (StreamHangAfterEvents is not null)
            {
                await StreamHangAfterEvents(cancellationToken).ConfigureAwait(false);
            }
        }

        /// <summary>Queue of acknowledge-alarm replies to return.</summary>
        public Queue<AcknowledgeAlarmReply> AcknowledgeAlarmReplies { get; } = new();

        /// <summary>List of received acknowledge-alarm requests.</summary>
        public List<AcknowledgeAlarmRequest> AcknowledgeAlarmRequests { get; } = [];

        /// <summary>List of received stream-alarms requests.</summary>
        public List<StreamAlarmsRequest> StreamAlarmsRequests { get; } = [];

        /// <summary>List of alarm feed messages to yield when streaming alarms.</summary>
        public List<AlarmFeedMessage> AlarmFeedMessages { get; } = [];

        /// <inheritdoc />
        public Task<AcknowledgeAlarmReply> AcknowledgeAlarmAsync(
            AcknowledgeAlarmRequest request,
            CancellationToken cancellationToken)
        {
            AcknowledgeAlarmRequests.Add(request);
            return Task.FromResult(AcknowledgeAlarmReplies.Dequeue());
        }

        /// <inheritdoc />
        public async IAsyncEnumerable<AlarmFeedMessage> StreamAlarmsAsync(
            StreamAlarmsRequest request,
            [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken)
        {
            StreamAlarmsRequests.Add(request);
            foreach (AlarmFeedMessage feedMessage in AlarmFeedMessages)
            {
                cancellationToken.ThrowIfCancellationRequested();
                await Task.Yield();
                yield return feedMessage;
            }
        }

        /// <summary>Galaxy test connection reply to return.</summary>
        public TestConnectionReply GalaxyTestConnectionReply { get; set; } = new() { Ok = true };

        /// <summary>Galaxy get last deploy time reply to return.</summary>
        public GetLastDeployTimeReply GalaxyGetLastDeployTimeReply { get; set; } = new() { Present = false };

        /// <summary>Galaxy discover hierarchy reply to return.</summary>
        public DiscoverHierarchyReply GalaxyDiscoverHierarchyReply { get; set; } = new();

        public Queue<DiscoverHierarchyReply> GalaxyDiscoverHierarchyReplies { get; } = new();

        /// <summary>List of received galaxy test connection requests.</summary>
        public List<TestConnectionRequest> GalaxyTestConnectionRequests { get; } = [];

        /// <summary>List of received galaxy get last deploy time requests.</summary>
        public List<GetLastDeployTimeRequest> GalaxyGetLastDeployTimeRequests { get; } = [];

        /// <summary>List of received galaxy discover hierarchy requests.</summary>
        public List<DiscoverHierarchyRequest> GalaxyDiscoverHierarchyRequests { get; } = [];

        /// <inheritdoc />
        public Task<TestConnectionReply> GalaxyTestConnectionAsync(
            TestConnectionRequest request,
            CancellationToken cancellationToken)
        {
            GalaxyTestConnectionRequests.Add(request);
            return Task.FromResult(GalaxyTestConnectionReply);
        }

        /// <inheritdoc />
        public Task<GetLastDeployTimeReply> GalaxyGetLastDeployTimeAsync(
            GetLastDeployTimeRequest request,
            CancellationToken cancellationToken)
        {
            GalaxyGetLastDeployTimeRequests.Add(request);
            return Task.FromResult(GalaxyGetLastDeployTimeReply);
        }

        /// <inheritdoc />
        public Task<DiscoverHierarchyReply> GalaxyDiscoverHierarchyAsync(
            DiscoverHierarchyRequest request,
            CancellationToken cancellationToken)
        {
            GalaxyDiscoverHierarchyRequests.Add(request);
            return Task.FromResult(
                GalaxyDiscoverHierarchyReplies.TryDequeue(out DiscoverHierarchyReply? reply)
                    ? reply
                    : GalaxyDiscoverHierarchyReply);
        }

        /// <summary>List of received galaxy watch deploy events requests.</summary>
        public List<WatchDeployEventsRequest> GalaxyWatchDeployEventsRequests { get; } = [];

        /// <summary>List of deploy events to yield when watching.</summary>
        public List<DeployEvent> GalaxyDeployEvents { get; } = [];

        /// <inheritdoc />
        public async IAsyncEnumerable<DeployEvent> GalaxyWatchDeployEventsAsync(
            WatchDeployEventsRequest request,
            [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken)
        {
            GalaxyWatchDeployEventsRequests.Add(request);
            foreach (DeployEvent deployEvent in GalaxyDeployEvents)
            {
                cancellationToken.ThrowIfCancellationRequested();
                await Task.Yield();
                yield return deployEvent;
            }
        }
    }
}