Feature/navigation lock (#809)

* feat: Added navigation interception

* Use parameter instead of field

Co-authored-by: Egil Hansen <egil@assimilated.dk>

* Remove whitespace

Co-authored-by: Egil Hansen <egil@assimilated.dk>

* fix: use static import to remove noise

* feat: Added exception handling for NavigationLock

* fix: remove obsolete property for test

* add: Changelog entry

* add: Documentation for NavigationLock

* refactor: Renamed Failed to Faulted for state

* fix: small tweaks to code docs and names

* fix: spelling

* remve lutconfig

Co-authored-by: Egil Hansen <egil@assimilated.dk>

CHANGELOG.md

@@ -36,6 +36,8 @@ All notable changes to **bUnit** will be documented in this file. The project ad
 
   By [@linkdotnet](https://github.com/linkdotnet) and [@egil](https://github.com/egil).
 
+- Added support for `NavigationLock`, which allows user code to intercept and prevent navigation. By [@linkdotnet](https://github.com/linkdotnet) and [@egil](https://github.com/egil).
+
 ### Fixed
 
 - `JSInterop.VerifyInvoke` reported the wrong number of actual invocations of a given identifier. Reported by [@otori](https://github.com/otori). Fixed by [@linkdotnet](https://github.com/linkdotnet).

docs/site/docs/test-doubles/fake-navigation-manager.md

@@ -71,3 +71,69 @@ Assert.Equal("http://localhost/foo", navMan.Uri);
 ```
 
 If a component issues multiple `NavigateTo` calls, then it is possible to inspect the navigation history by accessing the <xref:Bunit.TestDoubles.FakeNavigationManager.History> property. It's a stack based structure, meaning the latest navigations will be first in the collection at index 0.
+
+## Asserting that a navigation was prevented with the `NavigationLock` component
+
+The `NavigationLock` component, which was introduced with .NET 7, gives the possibility to intercept the navigation and can even prevent it. bUnit will always create a history entry for prevented or even failed interceptions. This gets reflected in the <xref:Bunit.TestDoubles.NavigationHistory.NavigationState> property, as well as in case of an exception on the <xref:Bunit.TestDoubles.NavigationHistory.Exception> property.
+
+A component can look like this:
+```razor
+@inject NavigationManager NavigationManager
+
+<button @onclick="(() => NavigationManager.NavigateTo("/counter"))">Counter</button> 
+
+<NavigationLock OnBeforeInternalNavigation="InterceptNavigation"></NavigationLock>
+
+@code {
+  private void InterceptNavigation(LocationChangingContext context)
+  {
+    context.PreventNavigation();
+  }
+}
+```
+
+A typical test, which asserts that the navigation got prevented, would look like this:
+
+```csharp
+using var ctx = new TestContext();
+var navMan = ctx.Services.GetRequiredService<FakeNavigationManager>();
+var cut = ctx.RenderComponent<InterceptComponent>();
+
+cut.Find("button").Click();
+
+// Assert that the navigation was prevented
+var navigationHistory = navMan.History.Single();
+Assert.Equal(NavigationState.Prevented, navigationHistory.NavigationState);
+```
+
+## Simulate preventing navigation from a `<a href>` with the `NavigationLock` component
+
+As `<a href>` navigation is not natively supported in bUnit, the `NavigationManager` can be used to simulate the exact behavior.
+
+```razor
+<a href="/counter">Counter</a>
+
+<NavigationLock OnBeforeInternalNavigation="InterceptNavigation"></NavigationLock>
+
+@code {
+  private void InterceptNavigation(LocationChangingContext context)
+  {
+    throw new Exception();
+  }
+}
+```
+
+The test utilizes the `NavigationManager` itself to achieve the same:
+
+```csharp
+using var ctx = new TestContext();
+var navMan = ctx.Services.GetRequiredService<FakeNavigationManager>();
+var cut = ctx.RenderComponent<InterceptAHRefComponent>();
+
+navMan.NavigateTo("/counter");
+
+// Assert that the navigation was prevented
+var navigationHistory = navMan.History.Single();
+Assert.Equal(NavigationState.Faulted, navigationHistory.NavigationState);
+Assert.NotNull(navigationHistory.Exception);
+```

src/bunit.web/JSInterop/BunitJSInterop.cs

@@ -143,6 +143,10 @@ private void AddCustomNet5Handlers()
 	private void AddCustomNet6Handlers()
 	{
 		AddInvocationHandler(new FocusOnNavigateHandler());
+#if NET7_0_OR_GREATER
+		AddInvocationHandler(new NavigationLockDisableNavigationPromptInvocationHandler());
+		AddInvocationHandler(new NavigationLockEnableNavigationPromptInvocationHandler());
+#endif
 	}
 #endif
 }

src/bunit.web/JSInterop/InvocationHandlers/Implementation/NavigationLockDisableNavigationPromptInvocationHandler.cs

@@ -0,0 +1,14 @@
+#if NET7_0_OR_GREATER
+namespace Bunit.JSInterop.InvocationHandlers.Implementation;
+
+internal sealed class NavigationLockDisableNavigationPromptInvocationHandler : JSRuntimeInvocationHandler
+{
+	private const string Identifier = "Blazor._internal.NavigationLock.disableNavigationPrompt";
+
+	internal NavigationLockDisableNavigationPromptInvocationHandler()
+		: base(inv => inv.Identifier.Equals(Identifier, StringComparison.Ordinal), isCatchAllHandler: true)
+	{
+		SetVoidResult();
+	}
+}
+#endif

src/bunit.web/JSInterop/InvocationHandlers/Implementation/NavigationLockEnableNavigationPromptInvocationHandler.cs

@@ -0,0 +1,14 @@
+#if NET7_0_OR_GREATER
+namespace Bunit.JSInterop.InvocationHandlers.Implementation;
+
+internal sealed class NavigationLockEnableNavigationPromptInvocationHandler : JSRuntimeInvocationHandler
+{
+	private const string Identifier = "Blazor._internal.NavigationLock.enableNavigationPrompt";
+
+	internal NavigationLockEnableNavigationPromptInvocationHandler()
+		: base(inv => inv.Identifier.Equals(Identifier, StringComparison.Ordinal), isCatchAllHandler: true)
+	{
+		SetVoidResult();
+	}
+}
+#endif

src/bunit.web/TestDoubles/NavigationManager/FakeNavigationManager.cs

@@ -1,4 +1,5 @@
 using Bunit.Rendering;
+using Microsoft.AspNetCore.Components.Routing;
 
 namespace Bunit.TestDoubles;
 
@@ -68,7 +69,6 @@ protected override void NavigateToCore(string uri, bool forceLoad)
 #endif
 
 #if NET6_0_OR_GREATER
-
 	/// <inheritdoc/>
 	protected override void NavigateToCore(string uri, NavigationOptions options)
 	{
@@ -85,12 +85,37 @@ protected override void NavigateToCore(string uri, NavigationOptions options)
 		if (options.ReplaceHistoryEntry && history.Count > 0)
 			history.Pop();
 
-		history.Push(new NavigationHistory(uri, options));
-
+#if NET7_0_OR_GREATER
+		renderer.Dispatcher.InvokeAsync(async () =>
+#else
 		renderer.Dispatcher.InvokeAsync(() =>
+#endif
 		{
 			Uri = absoluteUri.OriginalString;
 
+#if NET7_0_OR_GREATER
+			var shouldContinueNavigation = false;
+			try
+			{
+				shouldContinueNavigation = await NotifyLocationChangingAsync(uri, options.HistoryEntryState, isNavigationIntercepted: false).ConfigureAwait(false);
+			}
+			catch (Exception exception)
+			{
+				history.Push(new NavigationHistory(uri, options, NavigationState.Faulted, exception));
+				return;
+			}
+
+			history.Push(new NavigationHistory(uri, options, shouldContinueNavigation ? NavigationState.Succeeded : NavigationState.Prevented));
+
+			if (!shouldContinueNavigation)
+			{
+				return;
+			}
+#else
+			history.Push(new NavigationHistory(uri, options));
+#endif
+
+
 			// Only notify of changes if user navigates within the same
 			// base url (domain). Otherwise, the user navigated away
 			// from the app, and Blazor's NavigationManager would
@@ -107,6 +132,15 @@ protected override void NavigateToCore(string uri, NavigationOptions options)
 	}
 #endif
 
+#if NET7_0_OR_GREATER
+	/// <inheritdoc/>
+	protected override void SetNavigationLockState(bool value) {}
+
+	/// <inheritdoc/>
+	protected override void HandleLocationChangingHandlerException(Exception ex, LocationChangingContext context)
+		=> throw ex;
+#endif
+
 	private URI GetNewAbsoluteUri(string uri)
 		=> URI.IsWellFormedUriString(uri, UriKind.Relative)
 			? ToAbsoluteUri(uri)
@@ -124,4 +158,4 @@ private static string GetBaseUri(URI uri)
 	{
 		return uri.Scheme + "://" + uri.Authority + "/";
 	}
-}
+}

src/bunit.web/TestDoubles/NavigationManager/NavigationHistory.cs

@@ -1,3 +1,5 @@
+using Microsoft.AspNetCore.Components.Routing;
+
 namespace Bunit.TestDoubles;
 
 /// <summary>
@@ -18,27 +20,66 @@ public sealed class NavigationHistory : IEquatable<NavigationHistory>
 	public Bunit.TestDoubles.NavigationOptions Options { get; }
 #endif
 #if NET6_0_OR_GREATER
-	public Microsoft.AspNetCore.Components.NavigationOptions Options { get; }
+	public NavigationOptions Options { get; }
 #endif
 
+#if NET7_0_OR_GREATER
+	/// <summary>
+	/// Gets the <see cref="NavigationState"/> associated with this history entry.
+	/// </summary>
+	public NavigationState State { get; }
+
+	/// <summary>
+	/// Gets the exception thrown from the <see cref="NavigationLock.OnBeforeInternalNavigation"/> handler, if any.
+	/// </summary>
+	/// <remarks>
+	/// Will not be null when <see cref="State"/> is <see cref="NavigationState.Faulted"/>.
+	/// </remarks>
+	public Exception? Exception { get; }
+#endif
+
+#if !NET6_0_OR_GREATER
 	/// <summary>
 	/// Initializes a new instance of the <see cref="NavigationHistory"/> class.
 	/// </summary>
 	/// <param name="uri"></param>
 	/// <param name="options"></param>
 	[SuppressMessage("Design", "CA1054:URI-like parameters should not be strings", Justification = "Using string to align with NavigationManager")]
-#if !NET6_0_OR_GREATER
 	public NavigationHistory(string uri, Bunit.TestDoubles.NavigationOptions options)
 	{
 		Uri = uri;
 		Options = options;
 	}
 #endif
-#if NET6_0_OR_GREATER
-	public NavigationHistory(string uri, Microsoft.AspNetCore.Components.NavigationOptions options)
+#if NET6_0
+	/// <summary>
+	/// Initializes a new instance of the <see cref="NavigationHistory"/> class.
+	/// </summary>
+	/// <param name="uri"></param>
+	/// <param name="options"></param>
+	[SuppressMessage("Design", "CA1054:URI-like parameters should not be strings", Justification = "Using string to align with NavigationManager")]
+	public NavigationHistory(string uri, NavigationOptions options)
+	{
+		Uri = uri;
+		Options = options;
+	}
+#endif
+
+#if NET7_0_OR_GREATER
+	/// <summary>
+	/// Initializes a new instance of the <see cref="NavigationHistory"/> class.
+	/// </summary>
+	/// <param name="uri"></param>
+	/// <param name="options"></param>
+	/// <param name="navigationState"></param>
+	/// <param name="exception"></param>
+	[SuppressMessage("Design", "CA1054:URI-like parameters should not be strings", Justification = "Using string to align with NavigationManager")]
+	public NavigationHistory(string uri, NavigationOptions options, NavigationState navigationState, Exception? exception = null)
 	{
 		Uri = uri;
 		Options = options;
+		State = navigationState;
+		Exception = exception;
 	}
 #endif
 

src/bunit.web/TestDoubles/NavigationManager/NavigationState.cs

@@ -0,0 +1,24 @@
+#if NET7_0_OR_GREATER
+namespace Bunit.TestDoubles;
+
+/// <summary>
+/// Describes the possible enumerations when a navigation gets intercepted.
+/// </summary>
+public enum NavigationState
+{
+	/// <summary>
+	/// The navigation was successfully executed.
+	/// </summary>
+	Succeeded,
+
+	/// <summary>
+	/// The navigation was prevented.
+	/// </summary>
+	Prevented,
+
+	/// <summary>
+	/// The OnBeforeInternalNavigation event handler threw an exception and the navigation did not complete.
+	/// </summary>
+	Faulted
+}
+#endif