namespace ZB.MOM.WW.ScadaBridge.Host.Tests;

/// <summary>
/// ScadaBridge#76: a routine Windows service stop must not be logged as
/// <c>[FTL] host terminated unexpectedly</c>.
/// </summary>
public class GracefulShutdownTests
{
    /// <summary>A cancellation escaping RunAsync after ApplicationStopping fired is a routine stop.</summary>
    [Fact]
    public void Cancellation_AfterStopRequested_IsGraceful()
    {
        using var cts = new CancellationTokenSource();
        cts.Cancel();

        Assert.True(Program.IsGracefulShutdown(new OperationCanceledException(), cts.Token));
        Assert.True(Program.IsGracefulShutdown(new TaskCanceledException(), cts.Token));
    }

    /// <summary>A cancellation with no shutdown requested is still a genuine failure.</summary>
    [Fact]
    public void Cancellation_WithoutStopRequested_IsNotGraceful()
    {
        using var cts = new CancellationTokenSource();

        Assert.False(Program.IsGracefulShutdown(new OperationCanceledException(), cts.Token));
        Assert.False(Program.IsGracefulShutdown(new OperationCanceledException(), CancellationToken.None));
    }

    /// <summary>A real fault during shutdown must still be reported as fatal.</summary>
    [Fact]
    public void NonCancellationException_IsNeverGraceful()
    {
        using var cts = new CancellationTokenSource();
        cts.Cancel();

        Assert.False(Program.IsGracefulShutdown(new InvalidOperationException("boom"), cts.Token));
    }
}