Add task extensions tests

Tests/Utils/TaskExtensionsTest.cs

@@ -0,0 +1,67 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Xunit;
+using DNS.Protocol.Utils;
+
+namespace DNS.Tests.Utils {
+
+    public class TaskExtensionsTest {
+        [Fact]
+        public async Task WithoutCancellation() {
+            object obj = new object();
+            CancellationTokenSource cts = new CancellationTokenSource();
+            TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
+            Task<object> resultTask = tcs.Task.WithCancellation(cts.Token);
+
+            tcs.SetResult(obj);
+            object result = await resultTask;
+
+            Assert.Same(obj, result);
+        }
+
+        [Fact]
+        public async Task WithCancellation() {
+            CancellationTokenSource cts = new CancellationTokenSource();
+            TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
+            Task resultTask = tcs.Task.WithCancellation(cts.Token);
+
+            cts.Cancel();
+
+            OperationCanceledException e =
+                await Assert.ThrowsAsync<OperationCanceledException>(() => resultTask);
+            Assert.Equal(cts.Token, e.CancellationToken);
+        }
+
+        [Fact]
+        public async Task WithoutCancellationTimeout() {
+            object obj = new object();
+            TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
+            Task<object> resultTask = tcs.Task.WithCancellationTimeout(TimeSpan.FromMilliseconds(60000));
+
+            tcs.SetResult(obj);
+            object result = await resultTask;
+
+            Assert.Same(obj, result);
+        }
+
+        [Fact(Timeout = 30000)]
+        public async Task WithoutCancellationTimeoutAndCancellationToken() {
+            CancellationTokenSource cts = new CancellationTokenSource();
+            TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
+            Task<object> resultTask = tcs.Task.WithCancellationTimeout(TimeSpan.FromMilliseconds(60000), cts.Token);
+
+            cts.Cancel();
+
+            await Assert.ThrowsAsync<OperationCanceledException>(() => resultTask);
+        }
+
+        [Fact]
+        public async Task WithCancellationTimeout() {
+            TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
+            Task resultTask = tcs.Task.WithCancellationTimeout(TimeSpan.FromMilliseconds(100));
+
+            await Assert.ThrowsAsync<OperationCanceledException>(() => resultTask);
+        }
+    }
+}