lmxopcua/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Tests/MTConnectBufferSizeWarningTests.cs

using System.Net;
using System.Net.Http;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Tests;

/// <summary>
///     lmxopcua#825 — a <c>SampleCount</c> above the Agent's <c>bufferSize</c> is refused <c>OUT_OF_RANGE</c> on
///     every <c>/sample</c> stream. The <c>/probe</c> header carries <c>bufferSize</c>, so Test Connect and the
///     driver's initialize (deploy) both warn instead of leaving it to surface as a Degraded stream.
/// </summary>
[Trait("Category", "Unit")]
public sealed class MTConnectBufferSizeWarningTests
{
    private static string ProbeXml(string? bufferSizeAttribute) =>
        $"""
         <?xml version="1.0" encoding="UTF-8"?>
         <MTConnectDevices xmlns="urn:mtconnect.org:MTConnectDevices:2.0">
           <Header instanceId="1"{(bufferSizeAttribute is null ? "" : $" bufferSize=\"{bufferSizeAttribute}\"")}/>
           <Devices>
             <Device id="d" name="D">
               <DataItems><DataItem id="d_avail" category="EVENT" type="AVAILABILITY"/></DataItems>
             </Device>
           </Devices>
         </MTConnectDevices>
         """;

    [Theory]
    [InlineData("16384", 16384L)]
    [InlineData(null, null)]
    [InlineData("0", null)]
    [InlineData("-5", null)]
    [InlineData("lots", null)]
    public void The_probe_parser_reads_the_header_buffer_size_and_never_fails_on_it(string? attribute, long? expected) =>
        MTConnectProbeParser.Parse(ProbeXml(attribute)).BufferSize.ShouldBe(expected);

    [Theory]
    [InlineData(16384, 16384L, false)] // live, cppagent 2.7: count == bufferSize is accepted
    [InlineData(16385, 16384L, true)]  // ... and bufferSize + 1 refused OUT_OF_RANGE
    [InlineData(20000, 16384L, true)]
    [InlineData(1_000_000, null, false)]
    public void The_warning_fires_only_above_the_buffer_size(int sampleCount, long? bufferSize, bool warns)
    {
        var warning = MTConnectDriver.SampleCountBufferWarning(sampleCount, bufferSize);
        (warning is not null).ShouldBe(warns);
        if (warns) warning!.ShouldContain($"at most {bufferSize}");
    }

    [Fact]
    public async Task Test_Connect_stays_ok_but_carries_the_warning_when_SampleCount_does_not_fit()
    {
        var probe = new MTConnectDriverProbe(new StubHandler(ProbeXml("16384")));
        var r = await probe.ProbeAsync(
            "{\"agentUri\":\"http://stub-agent:5000\",\"sampleCount\":16385}", TimeSpan.FromSeconds(3),
            TestContext.Current.CancellationToken);

        r.Ok.ShouldBeTrue("the Agent answered — reachability is not the problem");
        r.Message!.ShouldContain("WARNING:");
        r.Message!.ShouldContain("bufferSize 16384");
    }

    [Fact]
    public async Task Test_Connect_checks_the_driver_default_when_SampleCount_is_absent()
    {
        // The default SampleCount is 1000 — an Agent with a tiny buffer refuses it too.
        var probe = new MTConnectDriverProbe(new StubHandler(ProbeXml("512")));
        var r = await probe.ProbeAsync(
            "{\"agentUri\":\"http://stub-agent:5000\"}", TimeSpan.FromSeconds(3), TestContext.Current.CancellationToken);

        r.Ok.ShouldBeTrue();
        r.Message!.ShouldContain("SampleCount 1000 is above the Agent's bufferSize 512");
    }

    [Fact]
    public async Task Test_Connect_message_is_unchanged_when_SampleCount_fits()
    {
        var probe = new MTConnectDriverProbe(new StubHandler(ProbeXml("16384")));
        var r = await probe.ProbeAsync(
            "{\"agentUri\":\"http://stub-agent:5000\",\"sampleCount\":16384}", TimeSpan.FromSeconds(3),
            TestContext.Current.CancellationToken);

        r.Ok.ShouldBeTrue();
        r.Message!.ShouldNotContain("WARNING");
    }

    [Theory]
    [InlineData(131073, true)]
    [InlineData(131072, false)]
    [InlineData(1000, false)]
    public async Task Initialize_warns_and_surfaces_the_buffer_size_on_the_diagnostics_bag(int sampleCount, bool warns)
    {
        var client = CannedAgentClient.FromFixtures(); // Fixtures/probe.xml: bufferSize="131072"
        client.Probe.BufferSize.ShouldBe(131072L);
        var logger = new RecordingDriverLogger();
        var driver = new MTConnectDriver(
            new MTConnectDriverOptions
            {
                AgentUri = "http://fixture-agent:5000",
                RequestTimeoutMs = 5000,
                SampleCount = sampleCount,
                Tags = [new MTConnectTagDefinition("dev1_pos", DriverDataType.Float64)],
            },
            "mt-825",
            _ => client,
            logger);
        try
        {
            await driver.InitializeAsync("{}", TestContext.Current.CancellationToken);

            logger.Warnings.Any(w => w.Contains("bufferSize", StringComparison.Ordinal)).ShouldBe(warns);
            driver.GetDiagnostics()["agentBufferSize"].ShouldBe("131072");
        }
        finally
        {
            await driver.ShutdownAsync(TestContext.Current.CancellationToken);
        }
    }

    private sealed class StubHandler(string probeXml) : HttpMessageHandler
    {
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken ct) =>
            Task.FromResult(new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent(probeXml, System.Text.Encoding.UTF8, "application/xml"),
            });
    }
}