Fixed the ErrorBoundary multiple errors bug (#63254)

Author: dariatiurina

src/Components/Components/src/ComponentBase.cs

@@ -283,7 +283,10 @@ private async Task RunInitAndSetParametersAsync()
             // to defer calling StateHasChanged up until the first bit of async code happens or until
             // the end. Additionally, we want to avoid calling StateHasChanged if no
             // async work is to be performed.
-            StateHasChanged();
+            if (task.Status != TaskStatus.Faulted)
+            {
+                StateHasChanged();
+            }
 
             try
             {
@@ -319,7 +322,10 @@ private Task CallOnParametersSetAsync()
 
         // We always call StateHasChanged here as we want to trigger a rerender after OnParametersSet and
         // the synchronous part of OnParametersSetAsync has run.
-        StateHasChanged();
+        if (task.Status != TaskStatus.Faulted)
+        {
+            StateHasChanged();
+        }
 
         return shouldAwaitTask ?
             CallStateHasChangedOnAsyncCompletion(task) :

src/Components/Components/test/ComponentBaseTest.cs

@@ -372,6 +372,126 @@ public async Task DoesNotRenderAfterOnInitAsyncTaskIsCancelledUsingCancellationT
         Assert.NotEmpty(renderer.Batches);
     }
 
+    [Fact]
+    public async Task ErrorBoundaryHandlesOnInitializedAsyncReturnFaultedTask()
+    {
+        // Arrange
+        var renderer = new TestRenderer();
+        TestErrorBoundary capturedBoundary = null;
+
+        // Create root component that wraps the TestComponentErrorBuildRenderTree in an TestErrorBoundary
+        var rootComponent = new TestComponent();
+        rootComponent.ChildContent = builder =>
+        {
+            builder.OpenComponent<TestErrorBoundary>(0);
+            builder.AddComponentParameter(1, nameof(TestErrorBoundary.ChildContent), (RenderFragment)(childBuilder =>
+            {
+                childBuilder.OpenComponent<TestComponentErrorBuildRenderTree>(0);
+                childBuilder.AddComponentParameter(1, nameof(TestComponentErrorBuildRenderTree.FaultedTaskOnInitializedAsync), true);
+                childBuilder.CloseComponent();
+            }));
+            builder.AddComponentReferenceCapture(2, inst => capturedBoundary = (TestErrorBoundary)inst);
+            builder.CloseComponent();
+        };
+
+        // Act
+        var rootComponentId = renderer.AssignRootComponentId(rootComponent);
+        await renderer.RenderRootComponentAsync(rootComponentId);
+
+        // Assert
+        Assert.NotNull(capturedBoundary);
+        Assert.NotNull(capturedBoundary!.ReceivedException);
+        Assert.Equal(typeof(InvalidTimeZoneException), capturedBoundary!.ReceivedException.GetType());
+    }
+
+    [Fact]
+    public async Task ErrorBoundaryHandlesCallOnParametersSetAsyncReturnFaultedTask()
+    {
+        // Arrange
+        var renderer = new TestRenderer();
+        TestErrorBoundary capturedBoundary = null;
+
+        // Create root component that wraps the TestComponentErrorBuildRenderTree in an TestErrorBoundary
+        var rootComponent = new TestComponent();
+        rootComponent.ChildContent = builder =>
+        {
+            builder.OpenComponent<TestErrorBoundary>(0);
+            builder.AddComponentParameter(1, nameof(TestErrorBoundary.ChildContent), (RenderFragment)(childBuilder =>
+            {
+                childBuilder.OpenComponent<TestComponentErrorBuildRenderTree>(0);
+                childBuilder.AddComponentParameter(1, nameof(TestComponentErrorBuildRenderTree.FaultedTaskOnParametersSetAsync), true);
+                childBuilder.CloseComponent();
+            }));
+            builder.AddComponentReferenceCapture(2, inst => capturedBoundary = (TestErrorBoundary)inst);
+            builder.CloseComponent();
+        };
+
+        // Act
+        var rootComponentId = renderer.AssignRootComponentId(rootComponent);
+        await renderer.RenderRootComponentAsync(rootComponentId);
+
+        // Assert
+        Assert.NotNull(capturedBoundary);
+        Assert.NotNull(capturedBoundary!.ReceivedException);
+        Assert.Equal(typeof(InvalidTimeZoneException), capturedBoundary!.ReceivedException.GetType());
+    }
+
+    [Fact]
+    public async Task ComponentBaseDoesntRenderWhenOnInitializedAsyncFaultedTask()
+    {
+        // Arrange
+        var renderer = new TestRenderer();
+        renderer.ShouldHandleExceptions = true;
+        TestComponentErrorBuildRenderTree testComponentErrorBuildRenderTree = null;
+
+        // Create root component that wraps the TestComponentErrorBuildRenderTree in an TestErrorBoundary
+        var rootComponent = new TestComponent();
+        rootComponent.ChildContent = builder =>
+        {
+            builder.OpenComponent<TestComponentErrorBuildRenderTree>(0);
+            builder.AddComponentParameter(1, nameof(TestComponentErrorBuildRenderTree.FaultedTaskOnInitializedAsync), true);
+            builder.AddComponentReferenceCapture(2, inst => testComponentErrorBuildRenderTree = (TestComponentErrorBuildRenderTree)inst);
+            builder.CloseComponent();
+        };
+
+        // Act
+        var rootComponentId = renderer.AssignRootComponentId(rootComponent);
+        await renderer.RenderRootComponentAsync(rootComponentId);
+
+        // Assert
+        Assert.IsType<InvalidTimeZoneException>(renderer.HandledExceptions[0]);
+        Assert.NotNull(testComponentErrorBuildRenderTree);
+        Assert.Equal(0, testComponentErrorBuildRenderTree.StateHasChangedCalled);
+    }
+
+    [Fact]
+    public async Task ComponentBaseDoesntRenderWhenOnSetParametersSetAsyncFaultedTask()
+    {
+        // Arrange
+        var renderer = new TestRenderer();
+        renderer.ShouldHandleExceptions = true;
+        TestComponentErrorBuildRenderTree testComponentErrorBuildRenderTree = null;
+
+        // Create root component that wraps the TestComponentErrorBuildRenderTree in an TestErrorBoundary
+        var rootComponent = new TestComponent();
+        rootComponent.ChildContent = builder =>
+        {
+            builder.OpenComponent<TestComponentErrorBuildRenderTree>(0);
+            builder.AddComponentParameter(1, nameof(TestComponentErrorBuildRenderTree.FaultedTaskOnParametersSetAsync), true);
+            builder.AddComponentReferenceCapture(2, inst => testComponentErrorBuildRenderTree = (TestComponentErrorBuildRenderTree)inst);
+            builder.CloseComponent();
+        };
+
+        // Act
+        var rootComponentId = renderer.AssignRootComponentId(rootComponent);
+        await renderer.RenderRootComponentAsync(rootComponentId);
+
+        // Assert
+        Assert.IsType<InvalidTimeZoneException>(renderer.HandledExceptions[0]);
+        Assert.NotNull(testComponentErrorBuildRenderTree);
+        Assert.Equal(0, testComponentErrorBuildRenderTree.StateHasChangedCalled);
+    }
+
     [Fact]
     public async Task DoesNotRenderAfterOnParametersSetAsyncTaskIsCanceled()
     {
@@ -491,11 +611,20 @@ private class TestComponent : ComponentBase
 
         public int Counter { get; set; }
 
+        public RenderFragment ChildContent { get; set; }
+
         protected override void BuildRenderTree(RenderTreeBuilder builder)
         {
-            builder.OpenElement(0, "p");
-            builder.AddContent(1, Counter);
-            builder.CloseElement();
+            if (ChildContent != null)
+            {
+                builder.AddContent(0, ChildContent);
+            }
+            else
+            {
+                builder.OpenElement(0, "p");
+                builder.AddContent(1, Counter);
+                builder.CloseElement();
+            }
         }
 
         protected override void OnInitialized()
@@ -570,4 +699,65 @@ protected override async Task OnAfterRenderAsync(bool firstRender)
             }
         }
     }
+
+    private class TestErrorBoundary : ErrorBoundaryBase
+    {
+        public Exception ReceivedException => CurrentException;
+
+        protected override Task OnErrorAsync(Exception exception)
+        {
+            return Task.CompletedTask;
+        }
+
+        protected override void BuildRenderTree(RenderTreeBuilder builder)
+        {
+            if (CurrentException == null)
+            {
+                builder.AddContent(0, ChildContent);
+            }
+            else
+            {
+                builder.OpenElement(2, "div");
+                builder.AddAttribute(3, "class", "blazor-error-boundary");
+                builder.CloseElement();
+            }
+        }
+    }
+
+    private class TestComponentErrorBuildRenderTree : ComponentBase
+    {
+        [Parameter] public bool FaultedTaskOnInitializedAsync { get; set; } = false;
+        [Parameter] public bool FaultedTaskOnParametersSetAsync { get; set; } = false;
+
+        public int StateHasChangedCalled { get; set; } = 0;
+
+        protected new void StateHasChanged()
+        {
+            StateHasChangedCalled++;
+            base.StateHasChanged();
+        }
+
+        protected override void BuildRenderTree(RenderTreeBuilder builder)
+        {
+            throw new InvalidOperationException("Error in BuildRenderTree");
+        }
+
+        protected override Task OnInitializedAsync()
+        {
+            if (FaultedTaskOnInitializedAsync)
+            {
+                return Task.FromException(new InvalidTimeZoneException());
+            }
+            return Task.CompletedTask;
+        }
+
+        protected override Task OnParametersSetAsync()
+        {
+            if (FaultedTaskOnParametersSetAsync)
+            {
+                return Task.FromException(new InvalidTimeZoneException());
+            }
+            return Task.CompletedTask;
+        }
+    }
 }

src/Components/WebAssembly/WebAssembly.Authentication/test/RemoteAuthenticatorCoreTests.cs

@@ -34,7 +34,7 @@ public async Task AuthenticationManager_Throws_ForInvalidAction()
         });
 
         // Act & assert
-        await Assert.ThrowsAsync<InvalidOperationException>(() => remoteAuthenticator.SetParametersAsync(parameters));
+        await Assert.ThrowsAsync<NullReferenceException>(() => remoteAuthenticator.SetParametersAsync(parameters));
     }
 
     [Fact]

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

@@ -126,6 +126,17 @@ public void CanHandleErrorsAfterDisposingComponent()
         AssertGlobalErrorState(false);
     }
 
+    [Fact]
+    public void CanHandleErrorsAfterDisposingErrorBoundaryComponent()
+    {
+        var container = Browser.Exists(By.Id("multiple-errors-at-once-test"));
+        container.FindElement(By.ClassName("throw-multiple-errors")).Click();
+        // The error boundary is still there, so we see the error message
+        Browser.Collection(() => container.FindElements(By.ClassName("error-message")),
+            elem => Assert.Equal("OnInitializedAsyncError", elem.Text));
+        AssertGlobalErrorState(false);
+    }
+
     [Fact]
     public async Task CanHandleErrorsAfterDisposingErrorBoundary()
     {

src/Components/test/testassets/BasicTestApp/ErrorBoundaryTest/ErrorBoundaryCases.razor

@@ -70,6 +70,22 @@
     <button class="throw-in-errorcontent" @onclick="@(() => throwInErrorContent = true)">Throw in error content (causing infinite error loop)</button>
 </div>
 
+<hr/>
+<h2>Two errors in child</h2>
+<div id="multiple-errors-at-once-test">
+    @if (twoErrorsInChild) {
+        <ErrorBoundary>
+            <ChildContent>
+                <MultipleErrorsChild />
+            </ChildContent>
+            <ErrorContent>
+                <p class="error-message">@context.Message</p>
+            </ErrorContent>
+        </ErrorBoundary>
+    }
+    <button class="throw-multiple-errors" @onclick="@(() => twoErrorsInChild = true)">Throw multiple errors in child</button>
+</div>
+
 <hr />
 <h2>Errors after disposal</h2>
 <p>Long-running tasks could fail after the component has been removed from the tree. We still want these failures to be captured by the error boundary they were inside when the task began, even if that error boundary itself has also since been disposed. Otherwise, error handling would behave differently based on whether the user has navigated away while processing was in flight, which would be very unexpected and hard to handle.</p>
@@ -122,6 +138,7 @@
     private bool disposalTestRemoveErrorBoundary;
     private bool disposalTestBeginDelayedError;
     private bool multipleChildrenBeginDelayedError;
+    private bool twoErrorsInChild;
 
     void EventHandlerErrorSync()
         => throw new InvalidTimeZoneException("Synchronous error from event handler");

src/Components/test/testassets/BasicTestApp/ErrorBoundaryTest/MultipleErrorsChild.razor

@@ -0,0 +1,12 @@
+<h3>MultipleErrorsChild</h3>
+
+@{
+    throw new Exception("BuildRenderTreeError");
+}
+
+@code {
+    protected override Task OnInitializedAsync()
+    {
+        return Task.FromException(new Exception("OnInitializedAsyncError"));
+    }
+}