Support for CUTs that call FocusAsync on an ElementReference

Author: egil

…onentSupport/BunitJSInteropExtensions.cs …eb/JSInterop/BunitJSInteropExtensions.cssrc/bunit.web/JSInterop/ComponentSupport/BunitJSInteropExtensions.cs renamed to src/bunit.web/JSInterop/BunitJSInteropExtensions.cs src/bunit.web/JSInterop/ComponentSupport/BunitJSInteropExtensions.cs renamed to src/bunit.web/JSInterop/BunitJSInteropExtensions.cs

@@ -1,20 +1,19 @@
-namespace Bunit.JSInterop.ComponentSupport
+namespace Bunit.JSInterop
 {
 	/// <summary>
 	/// Helper methods for registering handlers on the <see cref="BunitJSInterop"/>.
 	/// </summary>
 	public static class BunitJSInteropExtensions
 	{
 		/// <summary>
-		/// Adds the built-in JSRuntime invocation handlers to the <paramref name="jSInterop"/>.
+		/// Adds the built-in JSRuntime invocation handlers to the <paramref name="jsInterop"/>.
 		/// </summary>
-		public static BunitJSInterop AddBuiltInJSRuntimeInvocationHandlers(this BunitJSInterop jSInterop)
+		public static BunitJSInterop AddBuiltInJSRuntimeInvocationHandlers(this BunitJSInterop jsInterop)
 		{
 #if NET5_0
-			//jSInterop.AddInvocationHandler(new Virtualize.VirtualizeJSRuntimeInvocationHandler());
+			jsInterop.AddInvocationHandler(new InvocationHandlers.FocusAsyncInvocationHandler());
 #endif
-			return jSInterop;
+			return jsInterop;
 		}
-
 	}
 }

src/bunit.web/JSInterop/InvocationHandlers/FocusAsyncAssertJSInteropExtensions.cs

@@ -0,0 +1,33 @@
+#if NET5_0
+using Bunit.JSInterop.InvocationHandlers;
+using Microsoft.AspNetCore.Components;
+using System.Collections.Generic;
+
+namespace Bunit
+{
+	/// <summary>
+	/// Extensions methods for verifying <see cref="ElementReferenceExtensions.FocusAsync(ElementReference)"/> method calls.
+	/// </summary>
+	public static class FocusAsyncAssertJSInteropExtensions
+	{
+		/// <summary>
+		/// Verifies that the <see cref="ElementReferenceExtensions.FocusAsync(ElementReference)"/> method has been invoked one time.
+		/// </summary>
+		/// <param name="handler">Handler to verify against.</param>		
+		/// <param name="userMessage">A custom user message to display if the assertion fails.</param>
+		/// <returns>The <see cref="JSRuntimeInvocation"/>.</returns>
+		public static JSRuntimeInvocation VerifyFocusAsyncInvoke(this BunitJSInterop handler, string? userMessage = null)
+			=> handler.VerifyInvoke(FocusAsyncInvocationHandler.FocusIdentifier, userMessage);
+
+		/// <summary>
+		/// Verifies that the <see cref="ElementReferenceExtensions.FocusAsync(ElementReference)"/> method has been invoked <paramref name="calledTimes"/> times.
+		/// </summary>
+		/// <param name="handler">Handler to verify against.</param>
+		/// <param name="calledTimes">The number of times the invocation is expected to have been called.</param>
+		/// <param name="userMessage">A custom user message to display if the assertion fails.</param>
+		/// <returns>The <see cref="JSRuntimeInvocation"/>.</returns>
+		public static IReadOnlyList<JSRuntimeInvocation> VerifyFocusAsyncInvoke(this BunitJSInterop handler, int calledTimes, string? userMessage = null)
+			=> handler.VerifyInvoke(FocusAsyncInvocationHandler.FocusIdentifier, calledTimes, userMessage);
+	}
+}
+#endif

src/bunit.web/JSInterop/InvocationHandlers/FocusAsyncInvocationHandler.cs

@@ -0,0 +1,31 @@
+#if NET5_0
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Components;
+
+namespace Bunit.JSInterop.InvocationHandlers
+{
+	/// <summary>
+	/// Represents a handler for Blazor's
+	/// <see cref="ElementReferenceExtensions.FocusAsync(ElementReference)"/> feature.
+	/// </summary>
+	public class FocusAsyncInvocationHandler : JSRuntimeInvocationHandler
+	{
+		/// <summary>
+		/// The internal identifier used by <see cref="ElementReferenceExtensions.FocusAsync(ElementReference)"/>
+		/// to call it JavaScript.
+		/// </summary>
+		public const string FocusIdentifier = "Blazor._internal.domWrapper.focus";
+
+		/// <summary>
+		/// Creates an instance of the <see cref="FocusEventDispatchExtensions"/>.
+		/// </summary>
+		protected internal FocusAsyncInvocationHandler() : base(FocusIdentifier, _ => true)
+		{
+		}
+	}
+}
+#endif

src/bunit.web/JSInterop/JSRuntimeAssertExtensions.cs

@@ -73,7 +73,7 @@ public static IReadOnlyList<JSRuntimeInvocation> VerifyInvoke(this BunitJSIntero
 		/// </summary>
 		/// <param name="actualArgument">object to verify.</param>
 		/// <param name="expectedTargetElement">expected targeted element.</param>
-		public static void ShouldBeElementReferenceTo(this object actualArgument, IElement expectedTargetElement)
+		public static void ShouldBeElementReferenceTo(this object? actualArgument, IElement expectedTargetElement)
 		{
 			if (actualArgument is null)
 				throw new ArgumentNullException(nameof(actualArgument));

src/bunit.web/RazorTesting/Fixture.cs

@@ -3,7 +3,7 @@
 using System.Linq;
 using System.Threading.Tasks;
 using Bunit.Extensions;
-using Bunit.JSInterop.ComponentSupport;
+using Bunit.JSInterop;
 using Bunit.RazorTesting;
 using Microsoft.AspNetCore.Components;
 using Microsoft.Extensions.DependencyInjection;

src/bunit.web/RazorTesting/SnapshotTest.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Threading.Tasks;
 using Bunit.Extensions;
-using Bunit.JSInterop.ComponentSupport;
+using Bunit.JSInterop;
 using Bunit.RazorTesting;
 using Bunit.Rendering;
 using Microsoft.AspNetCore.Components;

src/bunit.web/TestContext.cs

@@ -1,6 +1,6 @@
 using System;
 using Bunit.Extensions;
-using Bunit.JSInterop.ComponentSupport;
+using Bunit.JSInterop;
 using Microsoft.AspNetCore.Components;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.JSInterop;

tests/bunit.web.tests/JSInterop/InvocationHandlers/FocusAsyncInvocationHandlerTest.cs

@@ -0,0 +1,43 @@
+#if NET5_0
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Components.Rendering;
+using Xunit;
+
+namespace Bunit.JSInterop.InvocationHandlers
+{
+	public class FocusAsyncInvocationHandlerTest : TestContext
+	{
+		[Fact(DisplayName = "Can render components that calls FocusAsync")]
+		public void Test001()
+		{
+			var cut = RenderComponent<FocusingComponent>();
+			var input = cut.Find("input");
+			JSInterop.VerifyFocusAsyncInvoke().Arguments[0].ShouldBeElementReferenceTo(input);
+		}
+
+		class FocusingComponent : ComponentBase
+		{
+			ElementReference elmRef;
+			protected override async Task OnAfterRenderAsync(bool firstRender)
+			{
+				if (firstRender)
+				{
+					await elmRef.FocusAsync();
+				}
+			}
+
+			protected override void BuildRenderTree(RenderTreeBuilder builder)
+			{
+				builder.OpenElement(1, "input");
+				builder.AddElementReferenceCapture(2, x => elmRef = x);
+				builder.CloseElement();
+			}
+		}
+	}
+}
+#endif