Added TaskQueue class

src/DotNext.Tests/Threading/Tasks/TaskQueueTests.cs

@@ -0,0 +1,105 @@
+namespace DotNext.Threading.Tasks;
+
+public class TaskQueueTests : Test
+{
+    [Fact]
+    public static async Task EmptyQueue()
+    {
+        var queue = new TaskQueue<Task>(10);
+        Null(queue.HeadTask);
+        False(queue.TryDequeue(out _));
+        Null(await queue.TryDequeueAsync());
+    }
+
+    [Fact]
+    public static async Task QueueOverflow()
+    {
+        var queue = new TaskQueue<Task>(3);
+        True(queue.TryEnqueue(Task.CompletedTask));
+        True(queue.TryEnqueue(Task.CompletedTask));
+        True(queue.TryEnqueue(Task.CompletedTask));
+        NotNull(queue.HeadTask);
+
+        var enqueueTask = queue.EnqueueAsync(Task.CompletedTask).AsTask();
+        False(enqueueTask.IsCompleted);
+
+        True(queue.TryDequeue(out var task));
+        True(task.IsCompleted);
+
+        await enqueueTask.WaitAsync(DefaultTimeout);
+        queue.Clear();
+    }
+
+    [Fact]
+    public static async Task EnumerateTasks()
+    {
+        var queue = new TaskQueue<Task>(3);
+        True(queue.TryEnqueue(Task.CompletedTask));
+        True(queue.TryEnqueue(Task.CompletedTask));
+        True(queue.TryEnqueue(Task.CompletedTask));
+
+        var count = 0;
+        await foreach (var task in queue)
+        {
+            Same(Task.CompletedTask, task);
+            count++;
+        }
+
+        Equal(3, count);
+    }
+
+    [Fact]
+    public static async Task EnumerateTasks2()
+    {
+        var queue = new TaskQueue<Task>(3);
+        True(queue.TryEnqueue(Task.CompletedTask));
+        True(queue.TryEnqueue(Task.CompletedTask));
+        True(queue.TryEnqueue(Task.CompletedTask));
+
+        var count = 0;
+        while (await queue.TryDequeueAsync() is { } task)
+        {
+            Same(Task.CompletedTask, task);
+            count++;
+        }
+
+        Equal(3, count);
+    }
+
+    [Fact]
+    public static async Task DelayedDequeue()
+    {
+        var queue = new TaskQueue<Task>(3);
+        var enqueueTask = queue.DequeueAsync().AsTask();
+        False(enqueueTask.IsCompleted);
+
+        True(queue.TryEnqueue(Task.CompletedTask));
+
+        await enqueueTask.WaitAsync(DefaultTimeout);
+        Null(await queue.TryDequeueAsync());
+    }
+
+    [Fact]
+    public static async Task DequeueCancellation()
+    {
+        var source = new TaskCompletionSource();
+        var queue = new TaskQueue<Task>(3);
+        True(queue.TryEnqueue(source.Task));
+
+        await ThrowsAnyAsync<OperationCanceledException>(queue.DequeueAsync(new(canceled: true)).AsTask);
+    }
+
+    [Fact]
+    public static async Task FailedTask()
+    {
+        var source = new TaskCompletionSource();
+        var queue = new TaskQueue<Task>(3);
+        True(queue.TryEnqueue(source.Task));
+
+        var dequeueTask = queue.DequeueAsync().AsTask();
+        False(dequeueTask.IsCompleted);
+
+        source.SetException(new Exception());
+        Same(source.Task, await dequeueTask);
+    }
+}