docs: Added docs and exposes via TestContext

Author: linkdotnet

docs/site/docs/interaction/index.md

@@ -11,3 +11,4 @@ This section covers the various ways to interact with a component under test, e.
 - **<xref:trigger-renders>:** This covers how to manually trigger a render cycle for a component under test.
 - **<xref:awaiting-async-state>:** This covers how to await one or more asynchronous changes to the state of a component under test before continuing the test.
 - **<xref:dispose-components>:** This covers how to dispose components and their children.
+- **<xref:render-modes>:** This covers the different render modes and their interaction with bUnit.

docs/site/docs/interaction/render-modes.md

@@ -0,0 +1,62 @@
+---
+uid: render-modes
+title: Support for render modes and renderer info    
+---
+
+# Support for render modes and the renderer info
+Render modes in Blazor Web Apps determine the hosting model and interactivity of components. The render mode for example can be applied to a component using the `@rendermode` directive. The [`RendererInfo`](https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.components.rendererinfo?view=aspnetcore-9.0) allows the application to determine the interactivity and location of the component. For more details, check out the [Blazor render modes](https://learn.microsoft.com/en-us/aspnet/core/blazor/components/render-modes?view=aspnetcore-9.0) documentation.
+
+## Setting the render mode for a component under test
+Setting the render mode can be done via the <xref:Bunit.TestContext.SetAssignedRenderMode(Microsoft.AspNetCore.Components.IComponentRenderMode)> method. The `SetAssignedRenderMode` method takes an [`IComponentRenderMode`](https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.components.icomponentrendermode?view=aspnetcore-9.0) object as a parameter. Normally this is one of the following types:
+ * [`InteractiveAutoRenderMode`](https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.components.web.interactiveautorendermode?view=aspnetcore-9.0)
+ * [`InteractiveServerRendeMode`](https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.components.web.interactiveserverrendermode?view=aspnetcore-9.0)
+ * [`InteractiveWebAssemblyRenderMode`](https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.components.web.interactivewebassemblyrendermode?view=aspnetcore-9.0)
+
+For ease of use the [`RenderMode`](https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.components.web.rendermode?view=aspnetcore-9.0) class defines all three of them.
+
+
+> [!NOTE]
+> Strictly speaking, this feature is available since `net8.0`. With `net9.0` Blazor exposes the information on `ComponentBase` via the `AssignedRenderMode` property.
+
+This methods emulates the behavior of the `@rendermode` directive in a test environment. The following example shows how to set the render mode for a component under test:
+
+```razor
+@inherits TestContext
+
+@code {
+  [Fact]
+  public void WhenRenderModeNonInteractive_DisableButton()
+  {
+    // Arrange
+    var cut = RenderComponent<MyComponent>(ps => ps.SetAssignedRenderMode(RenderMode.InteractiveServer));
+```
+
+## Setting the `RendererInfo` for a component under test
+To set the `RendererInfo` for a component under test, use the `SetRendererInfo` method on the `TestContext` class. The `SetRendererInfo` method takes an optional `RendererInfo` object as a parameter. A component might check if interactivity is given to enable a button:
+
+```razor
+<button @onclick="Send" disabled="@(!RendererInfo.IsInteractive)">
+    Send
+</button>
+```
+
+In the test, you can set the `RendererInfo` to enabl or disable the button:
+
+```csharp
+@inherits TestContext
+
+@code {
+  [Fact]
+  public void WhenRenderModeNonInteractive_DisableButton()
+  {
+    // Arrange
+    SetRendererInfo(new RendererInfo("Server", false));
+
+    // Act
+    var cut = RenderComponent<MyComponent>();
+
+    // Assert
+    cut.Find("button").Attributes["disabled"].ShouldBe("disabled");
+  }
+}
+```

src/bunit.core/TestContextBase.cs

@@ -118,4 +118,14 @@ public void DisposeComponents()
 	{
 		Renderer.DisposeComponents();
 	}
+
+#if NET9_0_OR_GREATER
+	/// <summary>
+	/// Sets the <see cref="RendererInfo"/> for the renderer.
+	/// </summary>
+	public void SetRendererInfo(RendererInfo? rendererInfo)
+	{
+		Renderer.SetRendererInfo(rendererInfo);
+	}
+#endif
 }

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

@@ -7,7 +7,7 @@
 	[Fact(DisplayName = "TestRenderer provides RendererInfo")]
 	public void Test001()
 	{
-		Renderer.SetRendererInfo(new RendererInfo("Server", true));
+		SetRendererInfo(new RendererInfo("Server", true));
 		var cut = RenderComponent<RendererInfoComponent>();
 
 		cut.MarkupMatches(