Log when an enhanced navigation fails (#62598)

* Added warning when enhanced navigation falls back to full page reload + test
* tests fix

Author: dariatiurina

src/Components/Web.JS/src/Services/NavigationEnhancement.ts

@@ -455,6 +455,7 @@ function enhancedNavigationIsEnabledForForm(form: HTMLFormElement): boolean {
 function retryEnhancedNavAsFullPageLoad(internalDestinationHref: string) {
   // The ? trick here is the same workaround as described in #10839, and without it, the user
   // would not be able to use the back button afterwards.
+  console.warn(`Enhanced navigation failed for destination ${internalDestinationHref}. Falling back to full page load.`);
   history.replaceState(null, '', internalDestinationHref + '?');
   location.replace(internalDestinationHref);
 }

src/Components/test/E2ETest/ServerRenderingTests/EnhancedNavigationTest.cs

@@ -73,6 +73,10 @@ public void CanNavigateToNonHtmlResponse()
         Navigate($"{ServerPathBase}/nav");
         Browser.Exists(By.TagName("nav")).FindElement(By.LinkText("Non-HTML page")).Click();
         Browser.Equal("Hello, this is plain text", () => Browser.Exists(By.TagName("html")).Text);
+
+        //Check if the fall back because of the non-html response sends a warning
+        var logs = Browser.GetBrowserLogs(LogLevel.Warning);
+        Assert.Contains(logs, log => log.Message.Contains("Enhanced navigation failed for destination") && log.Message.Contains("Falling back to full page load.") && !log.Message.Contains("Error"));
     }
 
     [Fact]
@@ -465,6 +469,11 @@ public void EnhancedNavNotUsedForNonBlazorDestinations()
         Browser.Exists(By.TagName("nav")).FindElement(By.LinkText("Non-Blazor HTML page")).Click();
         Browser.Equal("This is a non-Blazor endpoint", () => Browser.Exists(By.TagName("h1")).Text);
         Assert.Equal("undefined", Browser.ExecuteJavaScript<string>("return typeof Blazor")); // Blazor JS is NOT loaded
+
+        //Check if the fall back because of the non-blazor endpoint navigation sends a warning
+        var logs = Browser.GetBrowserLogs(LogLevel.Warning);
+        Assert.Contains(logs, log => log.Message.Contains("Enhanced navigation failed for destination") && log.Message.Contains("Falling back to full page load.") && !log.Message.Contains("Error"));
+
     }
 
     [Theory]