Add overloads to InvokeAsync with a return value

Closes #1296

CHANGELOG.md

@@ -14,6 +14,10 @@ All notable changes to **bUnit** will be documented in this file. The project ad
 
 - When the `TestContext` was disposed, the Blazor Renderer itself didn't dispose components under test. By [@linkdotnet](https://github.com/linkdotnet).
 
+### Added
+
+- New overloads for `IRenderedFragmentBase.InvokeAsync` that allow retrieving the work item's return value. By [@jcparkyn](https://github.com/jcparkyn).
+
 ## [1.25.3] - 2023-11-14
 
 -   Upgrade all .NET 8 preview dependencies to .NET 8 stable.

src/bunit.core/Extensions/RenderedFragmentInvokeAsyncExtensions.cs

@@ -36,4 +36,34 @@ public static Task InvokeAsync(this IRenderedFragmentBase renderedFragment, Func
 		return renderedFragment.Services.GetRequiredService<ITestRenderer>()
 			.Dispatcher.InvokeAsync(workItem);
 	}
+
+	/// <summary>
+	/// Invokes the given <paramref name="workItem"/> in the context of the associated <see cref="ITestRenderer"/>.
+	/// </summary>
+	/// <param name="renderedFragment">The rendered component whose dispatcher to invoke with.</param>
+	/// <param name="workItem">The work item to execute on the renderer's thread.</param>
+	/// <returns>A <see cref="Task"/> that will be completed when the action has finished executing, with the return value from <paramref name="workItem"/>.</returns>
+	public static Task<T> InvokeAsync<T>(this IRenderedFragmentBase renderedFragment, Func<T> workItem)
+	{
+		if (renderedFragment is null)
+			throw new ArgumentNullException(nameof(renderedFragment));
+
+		return renderedFragment.Services.GetRequiredService<ITestRenderer>()
+			.Dispatcher.InvokeAsync(workItem);
+	}
+
+	/// <summary>
+	/// Invokes the given <paramref name="workItem"/> in the context of the associated <see cref="ITestRenderer"/>.
+	/// </summary>
+	/// <param name="renderedFragment">The rendered component whose dispatcher to invoke with.</param>
+	/// <param name="workItem">The work item to execute on the renderer's thread.</param>
+	/// <returns>A <see cref="Task"/> that will be completed when the action has finished executing, with the return value from <paramref name="workItem"/>.</returns>
+	public static Task<T> InvokeAsync<T>(this IRenderedFragmentBase renderedFragment, Func<Task<T>> workItem)
+	{
+		if (renderedFragment is null)
+			throw new ArgumentNullException(nameof(renderedFragment));
+
+		return renderedFragment.Services.GetRequiredService<ITestRenderer>()
+			.Dispatcher.InvokeAsync(workItem);
+	}
 }