feat: Blazor tests added

WotBlitzStatisticsPro.Blazor.Tests/Pages/MainLayoutTest.cs

@@ -0,0 +1,53 @@
+using System.Threading;
+using Bunit;
+using FluentAssertions;
+using Moq;
+using NUnit.Framework;
+using WotBlitzStatisticsPro.Blazor.Messages;
+using WotBlitzStatisticsPro.Blazor.Shared;
+
+namespace WotBlitzStatisticsPro.Blazor.Tests.Pages
+{
+    public class MainLayoutTest: TestContextBase
+    {
+        private IRenderedComponent<MainLayout> _component;
+
+        [SetUp]
+        public void Setup()
+        {
+            _component = TestContext?.RenderComponent<MainLayout>();
+        }
+
+        [Test]
+        public void ShouldFireMediatorEventEachTimeWhenLanguageChanged()
+        {
+            // =====================================
+            // Hint for css selector
+            /*
+By.css('.classname')          // get by class name
+By.css('input[type=radio]')   // get input by type radio
+By.css('.parent .child')      // get child who has a parent
+             */
+
+            // Take a look at the component text
+            // var html = _component.Markup;
+
+            // =====================================
+
+            // All 3 languages in a RadzenSplitButton
+            var elements = _component.FindAll(".rz-menuitem");
+
+            elements.Should().NotBeNull();
+            elements.Count.Should().Be(3);
+
+            string[] expectedLanguages = {"en-US", "ru-RU", "de-DE"};
+            for (int i = 0; i < 3; i++)
+            {
+                elements[i].Click();
+                MediatorMock.Verify(m => m.Publish(
+                    It.Is<ChangeCurrentCultureMessage>(m => m.CultureName == expectedLanguages[0]), 
+                    It.IsAny<CancellationToken>()), Times.Once);
+            }
+        }
+    }
+}