chore: All WebView runtime tests pass on Android

src/Uno.UI/UI/Xaml/Controls/WebView/Core/CoreWebView2.cs

@@ -45,7 +45,10 @@ public partial class CoreWebView2
 		}
 
 		_processedSource = actualUri;
-		Source = actualUri.ToString();
+		if (_owner.SwitchSourceBeforeNavigating)
+		{
+			Source = actualUri.ToString();
+		}
 
 		UpdateFromInternalSource();
 	}
@@ -53,7 +56,10 @@ public partial class CoreWebView2
 	public void NavigateToString(string htmlContent)
 	{
 		_processedSource = htmlContent;
-		Source = BlankUrl;
+		if (_owner.SwitchSourceBeforeNavigating)
+		{
+			Source = BlankUrl;
+		}
 
 		UpdateFromInternalSource();
 	}
@@ -66,7 +72,10 @@ public partial class CoreWebView2
 		}
 
 		_processedSource = requestMessage;
-		Source = requestMessage.RequestUri.ToString();
+		if (_owner.SwitchSourceBeforeNavigating)
+		{
+			Source = requestMessage.RequestUri.ToString();
+		}
 
 		UpdateFromInternalSource();
 	}

src/Uno.UI/UI/Xaml/Controls/WebView/IWebView.cs

@@ -2,5 +2,7 @@
 
 internal interface IWebView
 {
+	bool SwitchSourceBeforeNavigating { get; }
+
 	bool IsLoaded { get; }
 }

src/Uno.UI/UI/Xaml/Controls/WebView/WebView1/WebView.cs

@@ -40,6 +40,8 @@ public partial class WebView : Control, IWebView
 
 	bool IWebView.IsLoaded => IsLoaded;
 
+	bool IWebView.SwitchSourceBeforeNavigating => true;
+
 	protected override void OnApplyTemplate() => CoreWebView2.OnOwnerApplyTemplate();
 
 	public void Navigate(global::System.Uri source) => CoreWebView2.Navigate(source.ToString());
@@ -54,18 +56,29 @@ public partial class WebView : Control, IWebView
 
 	public void Stop() => CoreWebView2.Stop();
 
-	public IAsyncOperation<string?> InvokeScriptAsync(string scriptName, IEnumerable<string> arguments)
+	public IAsyncOperation<string?> InvokeScriptAsync(string scriptName, IEnumerable<string> arguments) =>
+		AsyncOperation.FromTask(ct => InvokeScriptAsync(ct, scriptName, arguments.ToArray()));
+
+	public async Task<string?> InvokeScriptAsync(CancellationToken ct, string script, string[] arguments)
 	{
 		var argumentString = ConcatenateJavascriptArguments(arguments);
-		var javaScript = string.Format(CultureInfo.InvariantCulture, "{0}(\"{1}\")", scriptName, argumentString);
-		return CoreWebView2.ExecuteScriptAsync(javaScript);
+		var javaScript = string.Format(CultureInfo.InvariantCulture, "{0}(\"{1}\")", script, argumentString);
+		return AdjustInvokeScriptResult(await CoreWebView2.ExecuteScriptAsync(javaScript));
 	}
 
-	public async Task<string> InvokeScriptAsync(CancellationToken ct, string script, string[] arguments)
+	private string? AdjustInvokeScriptResult(string result)
 	{
-		var argumentString = ConcatenateJavascriptArguments(arguments);
-		var javaScript = string.Format(CultureInfo.InvariantCulture, "{0}(\"{1}\")", script, argumentString);
-		return await CoreWebView2.ExecuteScriptAsync(javaScript);
+		if (result is null)
+		{
+			return null;
+		}
+
+		if (result.StartsWith("\"", StringComparison.Ordinal) && result.EndsWith("\"", StringComparison.Ordinal))
+		{
+			return result.Substring(1, result.Length - 2);
+		}
+
+		return "";
 	}
 
 	public void NavigateWithHttpRequestMessage(global::System.Net.Http.HttpRequestMessage requestMessage) =>

src/Uno.UI/UI/Xaml/Controls/WebView/WebView2/WebView2.cs

@@ -42,6 +42,8 @@ public partial class WebView2 : Control, IWebView
 
 	bool IWebView.IsLoaded => IsLoaded;
 
+	bool IWebView.SwitchSourceBeforeNavigating => false; // WebView2 switches source only when navigation completes.
+
 	protected override void OnApplyTemplate() => CoreWebView2.OnOwnerApplyTemplate();
 
 	private void WebView2_Loaded(object sender, Windows.UI.Xaml.RoutedEventArgs e) =>