Add tests for ViewModels.ViewModelLocator

ThScoreFileConverter.Tests/ViewModels/ViewModelLocatorTests.cs

@@ -0,0 +1,33 @@
+using CommunityToolkit.Mvvm.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection;
+using MvvmDialogs;
+using NSubstitute;
+using ThScoreFileConverter.Adapters;
+using ThScoreFileConverter.Models;
+using ThScoreFileConverter.ViewModels;
+
+namespace ThScoreFileConverter.Tests.ViewModels;
+
+[TestClass]
+public class ViewModelLocatorTests
+{
+    [TestMethod]
+    public void MainWindowTest()
+    {
+        using var provider = new ServiceCollection()
+            .AddSingleton(Substitute.For<IDialogService>())
+            .AddSingleton(Substitute.For<IDispatcherAdapter>())
+            .AddSingleton(Substitute.For<IResourceDictionaryAdapter>())
+            .AddSingleton(new Settings())
+            .AddSingleton(Substitute.For<INumberFormatter>())
+            .AddTransient<MainWindowViewModel>()
+            .BuildServiceProvider();
+
+        Ioc.Default.ConfigureServices(provider);
+
+        using var window = new ViewModelLocator().MainWindow;
+        Assert.IsNotNull(window);
+
+        // NOTE: Ioc.Default can't be configured twice.
+    }
+}