Make flaky focus tests more deterministic and more verbose.

Author: ilonatommy

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

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Components.TestServer.RazorComponents;
+using Microsoft.AspNetCore.Components.E2ETest;
 using Microsoft.AspNetCore.Components.E2ETest.Infrastructure;
 using Microsoft.AspNetCore.Components.E2ETest.Infrastructure.ServerFixtures;
 using Microsoft.AspNetCore.E2ETesting;
@@ -59,19 +60,34 @@ public void FocusIsMoved_OnEnhancedNavigation_WhenAnyElementMatchesSelector()
     {
         Navigate($"{ServerPathBase}/focus-on-navigate");
         Browser.Click(By.LinkText("Statically rendered"));
-        Browser.True(() => Browser.SwitchTo().ActiveElement().GetDomAttribute("data-focus-on-navigate") is not null);
+        Browser.True(
+            () => Browser.SwitchTo().ActiveElement().GetDomAttribute("data-focus-on-navigate") is not null,
+            TimeSpan.FromSeconds(5)
+        );
     }
 
     [Fact]
     public void FocusIsPreserved_OnEnhancedFormPost_WhenAnyElementMatchesSelector()
     {
         Navigate($"{ServerPathBase}/focus-on-navigate");
         Browser.Click(By.LinkText("Form submission"));
-        Browser.True(() => Browser.SwitchTo().ActiveElement().GetDomAttribute("id") == "value-to-submit");
-        Browser.FindElement(By.Id("value-to-submit")).ReplaceText("Some value");
-        Browser.Click(By.Id("submit-button"));
+        string valueToSubmit = "value-to-submit";
+        AssertFocusPreserved(valueToSubmit);
+        Browser.FindElement(By.Id(valueToSubmit)).ReplaceText("Some value");
+        string submitButtonId = "submit-button";
+        Browser.Click(By.Id(submitButtonId));
         Browser.Equal("Some value", () => Browser.FindElement(By.Id("submitted-value")).Text);
-        Browser.True(() => Browser.SwitchTo().ActiveElement().GetDomAttribute("id") == "submit-button");
+        AssertFocusPreserved(submitButtonId);
+    }
+
+    private void AssertFocusPreserved(string elementId)
+    {
+        Browser.WaitForElementToBeVisible(By.Id(elementId));
+        Browser.True(
+            () => Browser.SwitchTo().ActiveElement().GetDomAttribute("id") == elementId,
+            TimeSpan.FromSeconds(5),
+            $"Expected element with id '{elementId}' to be focused, but found '{Browser.SwitchTo().ActiveElement().GetDomAttribute("id")}' instead."
+        );
     }
 
     [Fact]

src/Shared/E2ETesting/WaitAssert.cs

@@ -35,6 +35,9 @@ public static void True(this IWebDriver driver, Func<bool> actual)
     public static void True(this IWebDriver driver, Func<bool> actual, TimeSpan timeout)
         => WaitAssertCore(driver, () => Assert.True(actual()), timeout);
 
+    public static void True(this IWebDriver driver, Func<bool> actual, TimeSpan timeout, string message)
+        => WaitAssertCore(driver, () => Assert.True(actual(), message), timeout);
+
     public static void False(this IWebDriver driver, Func<bool> actual)
         => WaitAssertCore(driver, () => Assert.False(actual()));