fix: support passing assigned render mode via parameter builder

Directory.Build.props

@@ -16,6 +16,7 @@
 		<ImplicitUsings>enable</ImplicitUsings>
 		<NoWarn>CA1014,NU5104,NETSDK1138,SYSLIB0051</NoWarn>
 		<CheckEolTargetFramework>false</CheckEolTargetFramework>
+		<SuppressTfmSupportBuildWarnings>true</SuppressTfmSupportBuildWarnings>
 
 		<!-- Used by code coverage -->
 		<DebugType>full</DebugType>

src/bunit.core/ComponentParameterCollection.cs

@@ -19,6 +19,14 @@ public class ComponentParameterCollection : ICollection<ComponentParameter>, IRe
 	/// <inheritdoc />
 	public bool IsReadOnly { get; }
 
+#if NET9_0_OR_GREATER
+	/// <summary>
+	/// Gets or sets the <see cref="IComponentRenderMode"/> that will be specified in
+	/// the render tree for component the parameters are being passed to.
+	/// </summary>
+	public IComponentRenderMode? RenderMode { get; set; }
+#endif
+
 	/// <summary>
 	/// Adds a <paramref name="item"/> to the collection.
 	/// </summary>
@@ -104,6 +112,9 @@ void AddComponent(RenderTreeBuilder builder)
 		{
 			builder.OpenComponent<TComponent>(0);
 			AddAttributes(builder);
+#if NET9_0_OR_GREATER
+			builder.AddComponentRenderMode(RenderMode);
+#endif
 			builder.CloseComponent();
 		}
 

src/bunit.core/ComponentParameterCollectionBuilder.cs

@@ -78,7 +78,7 @@ public ComponentParameterCollectionBuilder<TComponent> Add<TChildComponent>(Expr
 	/// <param name="parameterSelector">A lambda function that selects the parameter.</param>
 	/// <param name="markup">The markup string to pass to the <see cref="RenderFragment"/>.</param>
 	/// <returns>This <see cref="ComponentParameterCollectionBuilder{TComponent}"/>.</returns>
-	public ComponentParameterCollectionBuilder<TComponent> Add(Expression<Func<TComponent, RenderFragment?>> parameterSelector, [StringSyntax("Html")]string markup)
+	public ComponentParameterCollectionBuilder<TComponent> Add(Expression<Func<TComponent, RenderFragment?>> parameterSelector, [StringSyntax("Html")] string markup)
 		=> Add(parameterSelector, markup.ToMarkupRenderFragment());
 
 	/// <summary>
@@ -266,7 +266,7 @@ public ComponentParameterCollectionBuilder<TComponent> AddChildContent(RenderFra
 	/// </summary>
 	/// <param name="markup">The markup string to pass the ChildContent parameter wrapped in a <see cref="RenderFragment"/>.</param>
 	/// <returns>This <see cref="ComponentParameterCollectionBuilder{TComponent}"/>.</returns>
-	public ComponentParameterCollectionBuilder<TComponent> AddChildContent([StringSyntax("Html")]string markup)
+	public ComponentParameterCollectionBuilder<TComponent> AddChildContent([StringSyntax("Html")] string markup)
 		=> AddChildContent(markup.ToMarkupRenderFragment());
 
 	/// <summary>
@@ -344,11 +344,11 @@ public ComponentParameterCollectionBuilder<TComponent> Bind<TValue>(
 		Action<TValue> changedAction,
 		Expression<Func<TValue>>? valueExpression = null)
 	{
-		#if !NET8_0_OR_GREATER
+#if !NET8_0_OR_GREATER
 		var (parameterName, _, isCascading) = GetParameterInfo(parameterSelector);
-		#else
+#else
 		var (parameterName, _, isCascading) = GetParameterInfo(parameterSelector, initialValue);
-		#endif
+#endif
 
 		if (isCascading)
 			throw new ArgumentException("Using Bind with a cascading parameter is not allowed.", parameterName);
@@ -397,6 +397,19 @@ static string TrimEnd(string source, string value)
 			: source;
 	}
 
+#if NET9_0_OR_GREATER
+	/// <summary>
+	/// Sets (or unsets) the <see cref="IComponentRenderMode"/> for the component and child components.
+	/// </summary>
+	/// <param name="renderMode">The render mode to assign to the component, e.g. <c>RenderMode.InteractiveServer</c>, or <see langword="null"/>, to not assign a specific render mode.</param>
+	/// <returns>This <see cref="ComponentParameterCollectionBuilder{TComponent}"/>.</returns>
+	public ComponentParameterCollectionBuilder<TComponent> SetAssignedRenderMode(IComponentRenderMode? renderMode)
+	{
+		parameters.RenderMode = renderMode;
+		return this;
+	}
+#endif
+
 	/// <summary>
 	/// Try to add a <paramref name="value"/> for a parameter with the <paramref name="name"/>, if
 	/// <typeparamref name="TComponent"/> has a property with that name, AND that property has a <see cref="ParameterAttribute"/>
@@ -454,14 +467,14 @@ Expression<Func<TComponent, TValue>> parameterSelector
 			: propInfoCandidate;
 
 		var paramAttr = propertyInfo?.GetCustomAttribute<ParameterAttribute>(inherit: true);
-	#if !NET8_0_OR_GREATER
+#if !NET8_0_OR_GREATER
 		var cascadingParamAttr = propertyInfo?.GetCustomAttribute<CascadingParameterAttribute>(inherit: true);
 
 		if (propertyInfo is null || (paramAttr is null && cascadingParamAttr is null))
 			throw new ArgumentException($"The parameter selector '{parameterSelector}' does not resolve to a public property on the component '{typeof(TComponent)}' with a [Parameter] or [CascadingParameter] attribute.", nameof(parameterSelector));
 
 		return (propertyInfo.Name, CascadingValueName: cascadingParamAttr?.Name, IsCascading: cascadingParamAttr is not null);
-	#else
+#else
 		var cascadingParamAttrBase = propertyInfo?.GetCustomAttribute<CascadingParameterAttributeBase>(inherit: true);
 
 		if (propertyInfo is null || (paramAttr is null && cascadingParamAttrBase is null))
@@ -494,7 +507,7 @@ static ArgumentException CreateErrorMessageForSupplyFromQuery(
 			                              NavigationManager.NavigateTo(uri);
 			                              """);
 		}
-	#endif
+#endif
 	}
 
 	private static bool HasChildContentParameter()

tests/bunit.core.tests/Rendering/RenderModeTests.razor

@@ -1,7 +1,9 @@
+@code{
+    #if NET9_0_OR_GREATER
+}
 @using Bunit.TestAssets.RenderModes;
 @inherits TestContext
 @code {
-#if NET9_0_OR_GREATER
 	[Fact(DisplayName = "TestRenderer provides RendererInfo")]
 	public void Test001()
 	{
@@ -104,7 +106,7 @@
 	public void Test009()
 	{
 		// See: https://learn.microsoft.com/en-us/aspnet/core/blazor/components/sections?view=aspnetcore-8.0#section-interaction-with-other-blazor-features
-		var cut = Render(@<SectionOutletComponent />);
+		var cut = Render(@<SectionOutletComponent><ComponentThatPrintsAssignedRenderMode/></SectionOutletComponent>);
 
 		cut.MarkupMatches(@<p>Assigned Render Mode: InteractiveWebAssemblyRenderMode</p>);
     }
@@ -125,6 +127,36 @@
             </text>);
 	}
 
+    [Fact(DisplayName = "SetAssignedRenderMode on root component")]
+    public void Test011()
+    {
+        var cut = RenderComponent<ComponentThatPrintsAssignedRenderMode>(ps => ps.SetAssignedRenderMode(RenderMode.InteractiveServer));
+        cut.MarkupMatches(@<p>Assigned Render Mode: InteractiveServerRenderMode</p>);
+    }
+
+    [Fact(DisplayName = "SetAssignedRenderMode on parent component cascades to children")]
+    public void Test012()
+    {
+        var cut = RenderComponent<ComponentWithChildContent>(ps => ps
+            .SetAssignedRenderMode(RenderMode.InteractiveWebAssembly)
+            .AddChildContent<ComponentThatPrintsAssignedRenderMode>());
+
+        cut.MarkupMatches(@<p>Assigned Render Mode: InteractiveWebAssemblyRenderMode</p>);
+    }
+
+    [Fact(DisplayName = "SetAssignedRenderMode child components")]
+    public void Test013()
+    {
+        var cut = RenderComponent<ComponentWithChildContent>(ps => ps
+            .AddChildContent<ComponentThatPrintsAssignedRenderMode>(pps => pps.SetAssignedRenderMode(RenderMode.InteractiveServer))
+            .AddChildContent<ComponentThatPrintsAssignedRenderMode>(pps => pps.SetAssignedRenderMode(RenderMode.InteractiveWebAssembly)));
+
+        cut.MarkupMatches(
+            @<text>
+                <p>Assigned Render Mode: InteractiveServerRenderMode</p>
+                <p>Assigned Render Mode: InteractiveWebAssemblyRenderMode</p>
+            </text>);
+    }
 
     [Fact(DisplayName = "Different assigned RenderMode between child and parent throws")]
 	public void Test020()
@@ -138,5 +170,7 @@
 
 		act.ShouldThrow<RenderModeMisMatchException>(); // todo: figure out good exception to use
     }
-#endif
+}
+@code{
+    #endif
 }

tests/bunit.testassets/RenderModes/SectionOutletComponent.cs

@@ -0,0 +1,30 @@
+using Microsoft.AspNetCore.Components.Web;
+
+#if NET8_0_OR_GREATER
+using Microsoft.AspNetCore.Components.Sections;
+#endif
+
+namespace Bunit.TestAssets.RenderModes;
+
+public class SectionOutletComponent : ComponentBase
+{
+#if NET8_0_OR_GREATER
+	private static readonly Guid SectionId = Guid.NewGuid();
+#endif
+
+	[Parameter] public RenderFragment ChildContent { get; set; }
+
+	protected override void BuildRenderTree(RenderTreeBuilder builder)
+	{
+#if NET8_0_OR_GREATER
+		builder.OpenComponent<SectionOutlet>(0);
+		builder.AddComponentParameter(1, nameof(SectionOutlet.SectionId), SectionId);
+		builder.AddComponentRenderMode(RenderMode.InteractiveWebAssembly);
+		builder.CloseComponent();
+		builder.OpenComponent<SectionContent>(10);
+		builder.AddComponentParameter(11, nameof(SectionContent.SectionId), SectionId);
+		builder.AddAttribute(12, nameof(SectionContent.ChildContent), ChildContent);
+		builder.CloseComponent();
+#endif
+	}
+}

tests/bunit.testassets/bunit.testassets.csproj

@@ -20,6 +20,7 @@
 		<PackageReference Include="xunit.abstractions" />		
 		<PackageReference Include="xunit.assert"  />
 		<PackageReference Include="Microsoft.Extensions.Localization.Abstractions" />
+		<PackageReference Include="Microsoft.AspNetCore.Components" />
 		<PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly" />
 		<PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.Authentication" />
 		<PackageReference Include="System.Text.Json" />