T1-4/T1-7: search engine resolver + site zoom store (TDD RED->GREEN, 32 tests)

VideoDownloader.Tests/Infrastructure/StaDispatcher.cs

@@ -0,0 +1,72 @@
+using System.Windows.Threading;
+
+namespace VideoDownloader.Tests.Infrastructure;
+
+/// <summary>
+/// WPF/WebView2 E2E 테스트용 STA 디스패처. 전용 STA 스레드에서 Dispatcher.Run() 으로
+/// 메시지 펌프를 돌리며, 테스트 코드는 InvokeAsync 로 UI 스레드에 작업을 올린다.
+/// WebView2 이벤트(비동기)는 UI 스레드 디스패처에서 발생하므로 async 흐름도 이 펌프 위에서 완결된다.
+/// </summary>
+public sealed class StaDispatcher : IDisposable
+{
+    private readonly Thread _thread;
+    private readonly TaskCompletionSource _ready = new(TaskCreationOptions.RunContinuationsAsynchronously);
+    private Dispatcher? _dispatcher;
+
+    private StaDispatcher(Thread thread)
+    {
+        _thread = thread;
+    }
+
+    public Dispatcher Dispatcher =>
+        _dispatcher ?? throw new InvalidOperationException("STA dispatcher not started");
+
+    public static StaDispatcher Start()
+    {
+        var sta = default(StaDispatcher)!;
+        var thread = new Thread(() =>
+        {
+            sta._dispatcher = Dispatcher.CurrentDispatcher;
+            sta._ready.TrySetResult();
+            Dispatcher.Run();
+        });
+        thread.SetApartmentState(ApartmentState.STA);
+        thread.IsBackground = true;
+        sta = new StaDispatcher(thread);
+        thread.Start();
+        sta._ready.Task.Wait(5000);
+        return sta;
+    }
+
+    public Task<T> InvokeAsync<T>(Func<Task<T>> func)
+        => Dispatcher.InvokeAsync(func).Task.Unwrap();
+
+    public Task InvokeAsync(Func<Task> func)
+        => Dispatcher.InvokeAsync(func).Task.Unwrap();
+
+    public T Invoke<T>(Func<T> func) => Dispatcher.Invoke(func);
+
+    public void Invoke(Action action) => Dispatcher.Invoke(action);
+
+    public void Dispose()
+    {
+        try { Dispatcher.InvokeShutdown(); } catch { }
+        try { _thread.Join(5000); } catch { }
+    }
+}
+
+/// <summary>WebView2 비동기 초기화/이벤트 대기 공통 유틸.</summary>
+public static class Wait
+{
+    public static async Task<T> Until<T>(Func<Task<T>> poll, Func<T, bool> done, int timeoutMs = 15000, int intervalMs = 100)
+    {
+        var sw = System.Diagnostics.Stopwatch.StartNew();
+        while (sw.ElapsedMilliseconds < timeoutMs)
+        {
+            var v = await poll();
+            if (done(v)) return v;
+            await Task.Delay(intervalMs);
+        }
+        throw new TimeoutException($"조건 미충족 ({timeoutMs}ms 초과)");
+    }
+}