Tests for change

Author: dariatiurina

src/Components/test/E2ETest/Tests/VirtualizationTest.cs

@@ -110,6 +110,33 @@ public void AlwaysFillsVisibleCapacity_Async()
         int GetPlaceholderCount() => Browser.FindElements(By.Id("async-placeholder")).Count;
     }
 
+    [Fact]
+    public void PlaceholdersHaveCorrectValue_Async()
+    {
+        Browser.MountTestComponent<VirtualizationQuickGrid>();
+
+        var finishLoadingButton = Browser.Exists(By.Id("finish-loading-button"));
+        
+        finishLoadingButton.Click(); //not waiting
+
+        Browser.True(() => Browser.Exists(By.Id("loadDone")).Text != "111");
+
+        Browser.True(() => GetItemCount() > 0);
+        Browser.Equal(0, () => GetPlaceholderCount());
+
+        Browser.ExecuteJavaScript("const container = document.getElementById('async-container'); container.scrollTop = container.scrollHeight * 0.5;");
+
+        Browser.Equal(0, () => GetItemCount());
+        Browser.True(() => GetPlaceholderCount() > 0);
+
+        //test that the other placeholder has ...
+        Browser.Equal("LOADING DATA", () => Browser.Exists(By.CssSelector(".async-placeholder")).Text);
+
+
+        int GetItemCount() => Browser.FindElements(By.CssSelector("#async-container tbody tr:not(:has(.grid-cell-placeholder))")).Count;
+        int GetPlaceholderCount() => Browser.FindElements(By.CssSelector(".grid-cell-placeholder")).Count;
+    }
+
     [Fact]
     public void RerendersWhenItemSizeShrinks_Sync()
     {

src/Components/test/testassets/BasicTestApp/Index.razor

@@ -117,6 +117,7 @@
         <option value="BasicTestApp.VirtualizationMaxItemCount">Virtualization MaxItemCount</option>
         <option value="BasicTestApp.VirtualizationMaxItemCount_AppContext">Virtualization MaxItemCount (via AppContext)</option>
         <option value="BasicTestApp.VirtualizationTable">Virtualization HTML table</option>
+        <option value="BasicTestApp.VirtualizationQuickGrid">Virtualization QuickGrid component</option>
         <option value="BasicTestApp.HotReload.RenderOnHotReload">Render on hot reload</option>
         <option value="BasicTestApp.SectionsTest.ParentComponentWithTwoChildren">Sections test</option>
         <option value="BasicTestApp.SectionsTest.SectionsWithCascadingParameters">Sections with Cascading parameters test</option>

src/Components/test/testassets/BasicTestApp/VirtualizationQuickGrid.razor

@@ -0,0 +1,80 @@
+@using Microsoft.AspNetCore.Components.QuickGrid
+
+
+@if (RendererInfo.IsInteractive)
+{
+    <button id="finish-loading-button" @onclick="@(async () => await FinishLoadingAsync(200))">Finish loading</button>
+}
+<br/>
+
+@if (boolLoad != "no condition")
+{
+    <p id="loadDone">@boolLoad</p>
+}
+
+<div id="async-container" style="height: 500px; overflow-y: auto;">
+    <QuickGrid @ref="asyncGrid" TGridItem="DataItem" ItemsProvider="GetItemsAsync" Virtualize="true" ItemSize="25">
+    <PropertyColumn Property="@(p => p.Id)" class="async-id">
+    </PropertyColumn>
+    <PropertyColumn Property="@(p => p.SecondNum)" class="async-second">
+        <PlaceholderTemplate>
+            <strong class="async-placeholder">LOADING DATA</strong>
+        </PlaceholderTemplate>
+    </PropertyColumn>
+</QuickGrid>
+</div>  
+
+@code {
+    record DataItem(int Id, int SecondNum);
+
+    QuickGrid<DataItem> asyncGrid;
+
+    int asyncTotalItemCount = 200;
+    int asyncCancellationCount = 0;
+    string boolLoad = "no condition";
+    TaskCompletionSource asyncTcs = new TaskCompletionSource();
+
+    private async ValueTask<GridItemsProviderResult<DataItem>> GetItemsAsync(GridItemsProviderRequest<DataItem> request)
+    {
+        var loadingTask = asyncTcs.Task;
+        var registration = request.CancellationToken.Register(() => CancelLoadingAsync(request.CancellationToken));
+
+        await loadingTask;
+
+        registration.Dispose();
+
+        var items = Enumerable.Range(request.StartIndex, request.Count ?? 200)
+            .Select(i => new DataItem(i, i * 2))
+            .ToArray();
+
+        return GridItemsProviderResult.From(items, asyncTotalItemCount);
+    }
+
+    async Task FinishLoadingAsync(int totalItemCount)
+    {
+        asyncTotalItemCount = totalItemCount;
+        asyncTcs.SetResult();
+        asyncTcs = new TaskCompletionSource();
+
+        if (asyncGrid is not null)
+        {
+            await asyncGrid.RefreshDataAsync();
+            boolLoad = "condition";
+        }
+        else
+        {
+            boolLoad = "asyncGrid null";
+        }
+        StateHasChanged();
+    }
+
+    void CancelLoadingAsync(System.Threading.CancellationToken cancellationToken)
+    {
+        asyncTcs.TrySetCanceled(cancellationToken);
+        asyncTcs = new TaskCompletionSource();
+
+        asyncCancellationCount++;
+
+        StateHasChanged();
+    }
+}

src/Components/test/testassets/Components.TestServer/RazorComponents/ComplexValidationComponent.razor

@@ -3,7 +3,7 @@
 @using Microsoft.AspNetCore.Components.Forms
 
 @if(RendererInfo.IsInteractive) {
-    <p id="is-interactive"></p>
+    <p id="is-interactive">111</p>
 }
 
 @if (_invalid)