Avalonia/tests/Avalonia.Headless.UnitTests/ThreadingTests.cs

using System;
using System.Threading;
using System.Threading.Tasks;
using Avalonia.Threading;

namespace Avalonia.Headless.UnitTests;

public class ThreadingTests
{
#if NUNIT
    [AvaloniaTest, Timeout(10000)]
#elif XUNIT
    [AvaloniaFact(Timeout = 10000)]
#endif
    public void Should_Be_On_Dispatcher_Thread()
    {
        Dispatcher.UIThread.VerifyAccess();
    }

#if NUNIT
    [AvaloniaTest(Ignore = "This test should always fail, enable to test if it fails")]
#elif XUNIT
    [AvaloniaFact(Skip = "This test should always fail, enable to test if it fails")]
#endif
    public void Should_Fail_Test_On_Delayed_Post_When_FlushDispatcher()
    {
        Dispatcher.UIThread.Post(() => throw new InvalidOperationException(), DispatcherPriority.Default);
    }
    
#if NUNIT
    [AvaloniaTheory, Timeout(10000), TestCase(1), TestCase(10), TestCase(100)]
#elif XUNIT
    [AvaloniaTheory(Timeout = 10000), InlineData(1), InlineData(10), InlineData(100)]
#endif
    public async Task DispatcherTimer_Works_On_The_Same_Thread(int interval)
    {
        await Task.Delay(100);

        var currentThread = Thread.CurrentThread;
        var tcs = new TaskCompletionSource();
        var hasCompleted = false;

        DispatcherTimer.RunOnce(() =>
        {
            hasCompleted = currentThread == Thread.CurrentThread;

            tcs.SetResult();
        }, TimeSpan.FromTicks(interval));

        await tcs.Task; 
        Assert.True(hasCompleted);
    }
}