vigilcare-clinical/VigilCareClinicalAPI.Tests/TrendDetectorTests.cs

using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using StackExchange.Redis;

[Collection("Integration")]
public class TrendDetectorTests : IAsyncLifetime
{
    private readonly ApiFixture _fixture;
    private Guid _encounterId;
    private Guid _patientId;
    private static readonly DateTimeOffset BaseTime =
        new(2026, 6, 18, 10, 0, 0, TimeSpan.Zero);

    public TrendDetectorTests(ApiFixture fixture) => _fixture = fixture;

    public async Task InitializeAsync()
    {
        using var scope = _fixture.Services.CreateScope();
        var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
        await DbResetHelper.ResetAsync(db);

        var patient = new Patient
        {
            Id = Guid.NewGuid(), Mrn = "MRN-TREND-001", FirstName = "Trend", LastName = "Test",
            DateOfBirth = new DateOnly(1970, 3, 1), Gender = "F",
            CreatedAt = DateTimeOffset.UtcNow
        };
        var encounter = new Encounter
        {
            Id = Guid.NewGuid(), PatientId = patient.Id, EncounterType = EncounterType.Inpatient,
            Status = EncounterStatus.Active, Department = Department.Icu,
            AttendingPhysician = "Dr. Trend", AdmittedAt = DateTimeOffset.UtcNow,
            CreatedAt = DateTimeOffset.UtcNow
        };
        db.Patients.Add(patient);
        db.Encounters.Add(encounter);
        await db.SaveChangesAsync();

        _patientId = patient.Id;
        _encounterId = encounter.Id;

        await ClearTrendHistoryAsync(scope.ServiceProvider);
    }

    public Task DisposeAsync() => Task.CompletedTask;

    [Fact]
    public async Task RapidHeartRateClimb_CreatesAlert()
    {
        using var scope = _fixture.Services.CreateScope();
        var detector = scope.ServiceProvider.GetRequiredService<TrendDetector>();

        await detector.ProcessObservationAsync(
            _encounterId, _patientId, "HEART_RATE", 72m, BaseTime);
        var result = await detector.ProcessObservationAsync(
            _encounterId, _patientId, "HEART_RATE", 95m, BaseTime.AddMinutes(10));

        result.Outcome.Should().Be(TrendOutcome.RapidDeterioration);
        result.AlertCreated.Should().BeTrue();
        result.RatePerMinute.Should().Be(2.3m);

        var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
        var alert = await db.ClinicalAlerts.SingleAsync();
        alert.AlertType.Should().Be(AlertType.RapidDeterioration);
        alert.Severity.Should().Be(AlertSeverity.Warning);
        alert.Details.Should().Contain("HEART_RATE");
    }

    [Fact]
    public async Task StableHighHeartRate_NoTrendAlert()
    {
        using var scope = _fixture.Services.CreateScope();
        var detector = scope.ServiceProvider.GetRequiredService<TrendDetector>();

        await detector.ProcessObservationAsync(
            _encounterId, _patientId, "HEART_RATE", 95m, BaseTime);
        await detector.ProcessObservationAsync(
            _encounterId, _patientId, "HEART_RATE", 95m, BaseTime.AddMinutes(10));
        var result = await detector.ProcessObservationAsync(
            _encounterId, _patientId, "HEART_RATE", 95m, BaseTime.AddMinutes(20));

        result.Outcome.Should().Be(TrendOutcome.Stable);
        result.AlertCreated.Should().BeFalse();

        var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
        (await db.ClinicalAlerts.CountAsync()).Should().Be(0);
    }

    [Fact]
    public async Task InsufficientHistory_NoAlert()
    {
        using var scope = _fixture.Services.CreateScope();
        var detector = scope.ServiceProvider.GetRequiredService<TrendDetector>();

        var result = await detector.ProcessObservationAsync(
            _encounterId, _patientId, "HEART_RATE", 72m, BaseTime);

        result.Outcome.Should().Be(TrendOutcome.InsufficientHistory);
        result.AlertCreated.Should().BeFalse();
    }

    [Fact]
    public async Task NonTrendCode_Ignored()
    {
        using var scope = _fixture.Services.CreateScope();
        var detector = scope.ServiceProvider.GetRequiredService<TrendDetector>();
        var redis = scope.ServiceProvider.GetRequiredService<IConnectionMultiplexer>();

        var result = await detector.ProcessObservationAsync(
            _encounterId, _patientId, "POTASSIUM_MEQ_L", 4.0m, BaseTime);

        result.Outcome.Should().Be(TrendOutcome.NotTrendCode);

        var key = TrendCalculator.HistoryKey(_encounterId, "POTASSIUM_MEQ_L");
        (await redis.GetDatabase().KeyExistsAsync(key)).Should().BeFalse();
    }

    [Fact]
    public async Task DuplicateTrendAlert_Idempotent()
    {
        using var scope = _fixture.Services.CreateScope();
        var detector = scope.ServiceProvider.GetRequiredService<TrendDetector>();
        var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();

        await detector.ProcessObservationAsync(
            _encounterId, _patientId, "HEART_RATE", 72m, BaseTime);
        await detector.ProcessObservationAsync(
            _encounterId, _patientId, "HEART_RATE", 95m, BaseTime.AddMinutes(10));

        var second = await detector.ProcessObservationAsync(
            _encounterId, _patientId, "HEART_RATE", 98m, BaseTime.AddMinutes(20));

        second.Outcome.Should().Be(TrendOutcome.AlertAlreadyOpen);
        second.AlertCreated.Should().BeFalse();
        (await db.ClinicalAlerts.CountAsync()).Should().Be(1,
            "second rapid climb must not duplicate while first RAPID_DETERIORATION is open");
    }

    private async Task ClearTrendHistoryAsync(IServiceProvider services)
    {
        var redis = services.GetRequiredService<IConnectionMultiplexer>();
        var cache = redis.GetDatabase();
        foreach (var key in TrendCalculator.AllHistoryKeys(_encounterId))
            await cache.KeyDeleteAsync(key);
    }
}