Reset browser window size in BrowserTestBase.DisposeAsync

Author: oroztocil

src/Components/test/E2ETest/Tests/StandaloneAppTest.cs

@@ -10,7 +10,7 @@
 namespace Microsoft.AspNetCore.Components.E2ETest.Tests;
 
 public class StandaloneAppTest
-    : ServerTestBase<BlazorWasmTestAppFixture<StandaloneApp.Program>>, IDisposable
+    : ServerTestBase<BlazorWasmTestAppFixture<StandaloneApp.Program>>
 {
     public StandaloneAppTest(
         BrowserFixture browserFixture,
@@ -22,6 +22,12 @@ public StandaloneAppTest(
 
     protected override void InitializeAsyncCore()
     {
+        // The sidebar is hidden if the screen is too narrow.
+        // Without setting the window size explicitly, visibility-sensitive properties (e.g. IWebElement.Text)
+        // and element finders (e.g. By.LinkText) can behave unexpectedly, causing assertions to fail.
+        // In particular, this happens in the headless mode (used when running without debugger).
+        Browser.SetWindowSize(1920, 1080);
+
         Navigate("/");
         WaitUntilLoaded();
     }
@@ -44,12 +50,6 @@ public void NavMenuHighlightsCurrentLocation()
         var activeNavLinksSelector = By.CssSelector(".sidebar a.active");
         var mainHeaderSelector = By.TagName("h1");
 
-        // The sidebar is hidden if the screen is too narrow.
-        // Without setting the window size explicitly, visibility-sensitive properties
-        // such as IWebElement.Text can return empty strings, causing assertions to fail.
-        // In particular, this happens in the headless mode (used when running without debugger).
-        Browser.SetWindowSize(1920, 1080);
-
         // Verify we start at home, with the home link highlighted
         Assert.Equal("Hello, world!", Browser.Exists(mainHeaderSelector).Text);
         Assert.Collection(Browser.FindElements(activeNavLinksSelector),
@@ -132,10 +132,12 @@ private void WaitUntilLoaded()
         Browser.NotEqual("Loading...", () => app.Text);
     }
 
-    public void Dispose()
+    public override async Task DisposeAsync()
     {
         // Make the tests run faster by navigating back to the home page when we are done
         // If we don't, then the next test will reload the whole page before it starts
         Browser.Exists(By.LinkText("Home")).Click();
+
+        await base.DisposeAsync();
     }
 }

src/Shared/E2ETesting/BrowserTestBase.cs

@@ -16,6 +16,7 @@ public class BrowserTestBase : IClassFixture<BrowserFixture>, IAsyncLifetime
 
     private ExceptionDispatchInfo _exceptionDispatchInfo;
     private IWebDriver _browser;
+    private System.Drawing.Size? _originalWindowSize;
 
     public BrowserTestBase(BrowserFixture browserFixture, ITestOutputHelper output)
     {
@@ -49,8 +50,13 @@ public IWebDriver Browser
 
     public BrowserFixture BrowserFixture { get; }
 
-    public Task DisposeAsync()
+    public virtual Task DisposeAsync()
     {
+        if (_originalWindowSize.HasValue && _originalWindowSize != Browser.Manage().Window.Size)
+        {
+            Browser.Manage().Window.Size = _originalWindowSize.Value;
+        }
+
         return Task.CompletedTask;
     }
 
@@ -78,6 +84,11 @@ protected void InitializeBrowser(string isolationContext)
             _asyncBrowser.Value = browser;
             _logs.Value = logs;
 
+            if (!_originalWindowSize.HasValue)
+            {
+                _originalWindowSize = browser.Manage().Window.Size;
+            }
+
             Browser = browser;
         }
         catch (Exception ex)