Merge pull request #265 from Lombiq/issue/LMBQ-137

LMBQ-137: Investigate and fix flaky visual verification UI tests

Lombiq.Tests.UI/Extensions/VisualVerificationUITestContextExtensions.cs

@@ -18,7 +18,6 @@
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Text;
-using System.Threading.Tasks;
 
 namespace Lombiq.Tests.UI.Extensions;
 
@@ -33,19 +32,22 @@ public static class VisualVerificationUITestContextExtensions
     /// Compares the baseline image and screenshot of the selected element on multiple different resolutions.
     /// </summary>
     /// <param name="sizes">The comparison is performed on each of these resolutions.</param>
-    /// <param name="beforeAssertAsync">
-    /// Task to be performed after the viewport has been resized but before the screenshot is taken. This can be used
-    /// for example if the page must be loaded in the given size.
-    /// </param>
     /// <param name="getSelector">
     /// Returns the selector for the given screen size. This may return the same selector all the time, or a different
     /// selector, e.g. if mobile and desktop views have different DOMs.
     /// </param>
+    /// <remarks>
+    /// <para>
+    /// The parameter <c>beforeAssertAsync</c> was removed, because it sometimes polluted the stack trace, which was
+    /// used in visual verification tests, so it caused tests to fail. The point of <c>beforeAssertAsync</c> was, that
+    /// sometimes the page can change on the resize window event. So the navigation happening after the window resize
+    /// ensures that the currently loaded page only existed with the desired screen size.
+    /// </para>
+    /// </remarks>
     [VisualVerificationApprovedMethod]
-    public static async Task AssertVisualVerificationOnAllResolutionsAsync(
+    public static void AssertVisualVerificationOnAllResolutions(
         this UITestContext context,
         IEnumerable<Size> sizes,
-        Func<Task> beforeAssertAsync,
         Func<Size, By> getSelector)
     {
         context.HideScrollbar();
@@ -54,7 +56,6 @@ public static async Task AssertVisualVerificationOnAllResolutionsAsync(
         foreach (var size in sizes)
         {
             context.SetViewportSize(size);
-            await beforeAssertAsync();
 
             try
             {