test: fix xUnit1051/xUnit1031 analyzer warnings

- Pass TestContext.Current.CancellationToken to all Task.Delay / Task.Run calls
- Replace blocking tcs.Task.Result with await (xUnit1031)
- Suppress xUnit1051 on intentionally-cancelled cts.Token in Task.Run

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: perditavojo

tests/InputBox.Tests/AnnouncementServiceTests.cs

@@ -39,7 +39,7 @@ public async Task Enqueue_EmptyString_DoesNotInvokeDelegate()
         _svc.Enqueue(string.Empty);
 
         // 等待足夠時間讓背景工作有機會執行
-        await Task.Delay(600);
+        await Task.Delay(600, TestContext.Current.CancellationToken);
 
         Assert.False(invoked);
     }
@@ -61,7 +61,7 @@ public async Task Enqueue_AfterDispose_DoesNotInvokeDelegate()
         _svc.Dispose();
         _svc.Enqueue("hello after dispose");
 
-        await Task.Delay(600);
+        await Task.Delay(600, TestContext.Current.CancellationToken);
 
         Assert.False(invoked);
     }
@@ -83,9 +83,10 @@ public async Task Enqueue_ValidMessage_EventuallyInvokesDelegate()
         _svc.Enqueue("測試廣播");
 
         // 等待最多 2 秒讓背景工作完成（含 ducking 延遲與 jitter）
-        string? received = await Task.WhenAny(tcs.Task, Task.Delay(2000)) == tcs.Task
-            ? tcs.Task.Result
-            : null;
+        Task<string> completionTask = tcs.Task;
+        Task timeoutTask = Task.Delay(2000, TestContext.Current.CancellationToken);
+        Task finished = await Task.WhenAny(completionTask, timeoutTask);
+        string? received = finished == completionTask ? await completionTask : null;
 
         Assert.Equal("測試廣播", received);
     }

tests/InputBox.Tests/TaskExtensionsTests.cs

@@ -77,7 +77,7 @@ public async Task SafeFireAndForget_SuccessfulTask_DoesNotInvokeOnException()
         Task.CompletedTask.SafeFireAndForget(
             onException: _ => exceptionInvoked = true);
 
-        await Task.Delay(100);
+        await Task.Delay(100, TestContext.Current.CancellationToken);
 
         Assert.False(exceptionInvoked);
     }
@@ -92,14 +92,17 @@ public async Task SafeFireAndForget_CancelledTask_DoesNotInvokeOnException()
         using var cts = new CancellationTokenSource();
         cts.Cancel();
 
+        // 此處 cts.Token 是刻意已取消的 token，pragma 抑制 xUnit1051 以保持測試語意清晰
+#pragma warning disable xUnit1051
         Task cancelledTask = Task.Run(
             () => cts.Token.ThrowIfCancellationRequested(),
             cts.Token);
+#pragma warning restore xUnit1051
 
         cancelledTask.SafeFireAndForget(
             onException: _ => exceptionInvoked = true);
 
-        await Task.Delay(150);
+        await Task.Delay(150, TestContext.Current.CancellationToken);
 
         Assert.False(exceptionInvoked);
     }
@@ -112,13 +115,15 @@ public async Task SafeFireAndForget_FaultedTask_InvokesOnException()
     {
         Exception? captured = null;
 
-        Task faultedTask = Task.Run(() => throw new InvalidOperationException("test-error"));
+        Task faultedTask = Task.Run(
+            () => throw new InvalidOperationException("test-error"),
+            TestContext.Current.CancellationToken);
 
         faultedTask.SafeFireAndForget(
             onException: ex => captured = ex);
 
         // 等待背景任務完成處理
-        await Task.Delay(300);
+        await Task.Delay(300, TestContext.Current.CancellationToken);
 
         Assert.NotNull(captured);
         Assert.IsType<InvalidOperationException>(captured);
@@ -133,12 +138,14 @@ public async Task SafeFireAndForget_WithAnnounceAction_InvokesWithMessage()
     {
         string? announced = null;
 
-        Task faultedTask = Task.Run(() => throw new Exception("announce-me"));
+        Task faultedTask = Task.Run(
+            () => throw new Exception("announce-me"),
+            TestContext.Current.CancellationToken);
 
         faultedTask.SafeFireAndForget(
             announceAction: msg => announced = msg);
 
-        await Task.Delay(300);
+        await Task.Delay(300, TestContext.Current.CancellationToken);
 
         Assert.NotNull(announced);
         Assert.Contains("announce-me", announced);
@@ -152,13 +159,15 @@ public async Task SafeFireAndForget_WithErrorMessageFormat_FormatsMessage()
     {
         string? announced = null;
 
-        Task faultedTask = Task.Run(() => throw new Exception("boom"));
+        Task faultedTask = Task.Run(
+            () => throw new Exception("boom"),
+            TestContext.Current.CancellationToken);
 
         faultedTask.SafeFireAndForget(
             announceAction: msg => announced = msg,
             errorMessageFormat: "錯誤：{0}");
 
-        await Task.Delay(300);
+        await Task.Delay(300, TestContext.Current.CancellationToken);
 
         Assert.Equal("錯誤：boom", announced);
     }