test(app): add docker and main window view model tests

tests/Vantage.App.Tests/DockerViewModelTests.cs

@@ -0,0 +1,47 @@
+using Vantage.App.ViewModels;
+using Vantage.Core.Docker;
+using Vantage.Core.Models;
+using Xunit;
+
+namespace Vantage.App.Tests;
+
+public class DockerViewModelTests
+{
+    [Fact]
+    public async Task RefreshAsync_PopulatesContainersForHost()
+    {
+        var viewModel = new DockerViewModel(new MockDockerProvider());
+        viewModel.SetHost(new HostConfig { Id = "h1" });
+
+        await viewModel.RefreshAsync(CancellationToken.None);
+
+        Assert.NotEmpty(viewModel.Containers);
+    }
+
+    [Fact]
+    public async Task RefreshAsync_WithoutHostDoesNothing()
+    {
+        var viewModel = new DockerViewModel(new MockDockerProvider());
+
+        await viewModel.RefreshAsync(CancellationToken.None);
+
+        Assert.Empty(viewModel.Containers);
+    }
+
+    [Fact]
+    public async Task StopCommand_TransitionsSelectedContainerToExited()
+    {
+        var viewModel = new DockerViewModel(new MockDockerProvider());
+        viewModel.SetHost(new HostConfig { Id = "h2" });
+        await viewModel.RefreshAsync(CancellationToken.None);
+
+        var running = viewModel.Containers.First(c => c.IsRunning);
+        viewModel.SelectedContainer = running;
+
+        await viewModel.StopCommand.ExecuteAsync(running);
+
+        var reloaded = viewModel.Containers.First(c => c.Id == running.Id);
+        Assert.Equal(ContainerState.Exited, reloaded.State);
+        Assert.False(reloaded.IsRunning);
+    }
+}