code REORG, pour partage pkg version entre app et tests

src/PostIt/PostIt.Tests/PostAclDialogTests.cs

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+using System.Net;
+using System.Text;
+using System.Text.Json;
+using Avalonia;
+using Avalonia.Headless.XUnit;
+using Microsoft.Extensions.DependencyInjection;
+using PostIt.Services;
+using PostIt.ViewModels;
+using PostIt.Views;
+using Yavsc.Api.Client;
+using Yavsc.Blogspot;
+
+namespace PostIt.Tests;
+
+/// <summary>
+/// Regression coverage for the user-reported bug:
+/// <c>PostAclDialogViewModel.LoadAsync</c> was never invoked,
+/// so <c>MyCircles</c> and <c>AclEntries</c> were empty when the
+/// dialog opened (the dropdown showed "Choisir un cercle..." and
+/// the list was blank, with no error to hint at why).
+///
+/// <para>The fix wires <see cref="PostAclDialog"/>'s constructor
+/// to trigger <c>LoadAsync</c> on the first
+/// <c>AttachedToVisualTree</c>, and the VM guards re-entry via
+/// <c>_loaded</c>. Two tests pin that contract:</para>
+/// <list type="bullet">
+///   <item><c>LoadAsync_runs_once_on_visual_attachment</c>: HTTP
+///   traffic shows up after the dialog is mounted.</item>
+///   <item><c>LoadAsync_is_idempotent</c>: a second explicit call
+///   to <c>LoadAsync</c> on the same VM hits the HTTP layer only
+///   once (the <c>_loaded</c> gate).</item>
+/// </list>
+///
+/// <para>HTTP is stubbed with a counter
+/// <see cref="HttpMessageHandler"/> that returns canned JSON
+/// <c>[]</c> for every request. The handler counts calls so the
+/// tests can assert "exactly one round-trip on mount" and
+/// "exactly one round-trip after two calls to LoadAsync". This
+/// is the same shape used by <c>BearerScopeTests</c>: real
+/// <see cref="YavscApiClient"/> subclass, real
+/// <see cref="HttpClient"/> with an injected handler, real
+/// <see cref="BlogAclApiClient"/> / <see cref="CircleApiClient"/>
+/// talking to it.</para>
+/// </summary>
+public class PostAclDialogTests
+{
+    /// <summary>
+    /// <see cref="HttpMessageHandler"/> that replies 200 with
+    /// <c>[]</c> (a valid JSON empty array, which both
+    /// <c>GetMyAclAsync</c> and <c>GetMyCirclesAsync</c> can
+    /// deserialize) and counts the number of requests.
+    /// </summary>
+    private sealed class CountingHttpHandler : HttpMessageHandler
+    {
+        public int RequestCount { get; private set; }
+
+        protected override Task<HttpResponseMessage> SendAsync(
+            HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            RequestCount++;
+            var response = new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent("[]", Encoding.UTF8, "application/json"),
+            };
+            return Task.FromResult(response);
+        }
+    }
+
+    /// <summary>
+    /// Subclass of <see cref="YavscApiClient"/> that routes HTTP
+    /// traffic through a caller-supplied
+    /// <see cref="HttpMessageHandler"/>. Same recipe as
+    /// <c>BearerScopeTests.TestableYavscApiClient</c> — we
+    /// override <c>CallAsync{T}</c> to talk to our own
+    /// <see cref="HttpClient"/> and skip the OIDC refresh path,
+    /// because the load-on-attach bug has nothing to do with
+    /// token refresh.
+    /// </summary>
+    private sealed class TestableYavscApiClient : YavscApiClient
+    {
+        private readonly HttpClient _http;
+
+        public TestableYavscApiClient(
+            Settings settings,
+            TokenStore store,
+            HttpMessageHandler handler)
+            : base(settings, store, oidc: null!)
+        {
+            _http = new HttpClient(handler, disposeHandler: false);
+        }
+
+        public override Task<T> CallAsync<T>(
+            HttpMethod method, string path, object? body = null,
+            CancellationToken ct = default)
+        {
+            var absolute = new Uri(new Uri(Settings.BusinessApiUrl), path);
+            using var req = new HttpRequestMessage(method, absolute);
+            using var resp = _http.SendAsync(req, ct).GetAwaiter().GetResult();
+            resp.EnsureSuccessStatusCode();
+            using var stream = resp.Content.ReadAsStream();
+            var dto = JsonSerializer.Deserialize<T>(stream,
+                new JsonSerializerOptions { PropertyNameCaseInsensitive = true });
+            return Task.FromResult(dto!);
+        }
+    }
+
+    /// <summary>
+    /// Build a minimal DI graph exposing the two API clients
+    /// (backed by a stub HTTP handler) and the page itself, so
+    /// <c>ViewLocator</c> can resolve the dialog from the VM.
+    /// Returns the handler, the API clients, and the window so
+    /// the test can assert on request counts and push the
+    /// dialog via the canonical <c>App.PushPageAsync</c> path.
+    /// The DI graph is built into a local <see cref="IServiceProvider"/>
+    /// that is NOT attached to <see cref="App.ServiceProvider"/>:
+    /// rebinding the global DI mid-test would trample the
+    /// Settings singleton the rest of the harness depends on.
+    /// </summary>
+    private static (MainWindow window, BlogAclApiClient aclClient, CircleApiClient circleClient, CountingHttpHandler handler) Mount()
+    {
+        var handler = new CountingHttpHandler();
+        var settings = new Settings();
+        var api = new TestableYavscApiClient(settings, new TokenStore(System.IO.Path.GetTempFileName()), handler);
+        var aclClient = new BlogAclApiClient(api, settings.BusinessApiUrl);
+        var circleClient = new CircleApiClient(api, settings.BusinessApiUrl);
+
+        var services = new ServiceCollection();
+        services.AddSingleton(settings);
+        services.AddSingleton(api);
+        services.AddSingleton(aclClient);
+        services.AddSingleton(circleClient);
+        services.AddTransient<PostAclDialog>();
+        var sp = services.BuildServiceProvider();
+        // Hold the sp alive for the test scope; otherwise the
+        // GC could collect the singletons between Mount() and
+        // the assertion below, and we'd lose the wiring to the
+        // CountingHttpHandler.
+        GC.KeepAlive(sp);
+
+        var window = new MainWindow();
+        var app = (App)Application.Current!;
+        app.DataTemplates.Clear();
+        app.DataTemplates.Add(new ViewLocator(sp));
+        app.AttachMainWindow(window);
+        window.Show();
+
+        return (window, aclClient, circleClient, handler);
+    }
+
+    /// <summary>
+    /// The bug: opening the dialog never called LoadAsync, so
+    /// MyCircles/AclEntries were empty. After the fix, setting
+    /// the dialog's DataContext to a PostAclDialogViewModel
+    /// (the same path App.PushPageAsync takes) must trigger
+    /// exactly one LoadAsync round-trip (the parallel WhenAll
+    /// inside the VM counts as one request per backend call,
+    /// hence two HTTP requests total: GET /blogacl and GET
+    /// /circle).
+    /// </summary>
+    [AvaloniaFact]
+    public async Task LoadAsync_runs_once_on_DataContext_changed()
+    {
+        // Arrange
+        var (window, aclClient, circleClient, handler) = Mount();
+        var post = new BlogPostDto { Id = 42, Title = "Test post" };
+
+        // Sanity: handler starts quiet.
+        Assert.Equal(0, handler.RequestCount);
+
+        // Act: push the dialog via the canonical VM-first pipeline.
+        // The locator goes through the parameterless ctor of
+        // PostAclDialog, then App.PushPageAsync assigns DataContext,
+        // which our hook intercepts to trigger LoadAsync.
+        var vm = new PostAclDialogViewModel(post, aclClient, circleClient);
+        await ((App)Application.Current!).PushPageAsync(vm);
+
+        // The dialog must be at the top of the nav stack and
+        // have its VM as DataContext.
+        var dialog = window.NavRoot.NavigationStack[^1] as PostAclDialog
+            ?? throw new InvalidOperationException("Dialog not at top of stack");
+        Assert.Same(vm, dialog.DataContext);
+
+        // Drain pending async work. LoadAsync is async and the
+        // DataContextChanged handler is fire-and-forget; a
+        // couple of loop turns is enough. We poll the handler
+        // counter because the dispatch back onto the headless
+        // dispatcher isn't strict — using a generous-but-bounded
+        // wait avoids test flakes.
+        var deadline = DateTime.UtcNow.AddSeconds(2);
+        while (handler.RequestCount < 2 && DateTime.UtcNow < deadline)
+        {
+            await Task.Delay(20);
+        }
+
+        // Assert: exactly two GETs went out (one to /blogacl,
+        // one to /circle), both from the LoadAsync call.
+        Assert.Equal(2, handler.RequestCount);
+
+        // And the VM's idempotency gate has flipped.
+        Assert.True(vm.Loaded);
+    }
+
+    /// <summary>
+    /// The fix exposes a guard on the VM too: a second call to
+    /// LoadAsync on the same instance must NOT issue more HTTP
+    /// traffic. This protects against the
+    /// DataContextChanged-firing-twice case (DataContext
+    /// overwritten mid-life, edge cases in dialog re-use).
+    /// </summary>
+    [AvaloniaFact]
+    public async Task LoadAsync_is_idempotent()
+    {
+        // Arrange
+        var (_, aclClient, circleClient, handler) = Mount();
+        var post = new BlogPostDto { Id = 99, Title = "Idempotency" };
+        var vm = new PostAclDialogViewModel(post, aclClient, circleClient);
+
+        // Act: invoke LoadAsync twice in a row.
+        await vm.LoadAsync();
+        await vm.LoadAsync();
+
+        // Assert: the second call short-circuited on _loaded.
+        Assert.Equal(2, handler.RequestCount);
+        Assert.True(vm.Loaded);
+    }
+}