From 1f1b78e50b973cea09a56f4b4ddf935cb002a1e6 Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Fri, 28 Aug 2026 16:37:39 +0200
Subject: [PATCH] test(app): add app test scaffolding and headless test harness

---
 .../Vantage.App.Tests/Fakes/StubProviders.cs  | 31 ++++++++++++++++
 tests/Vantage.App.Tests/HeadlessTestApp.cs    | 15 ++++++++
 .../Vantage.App.Tests/HeadlessWindowTests.cs  | 37 +++++++++++++++++++
 .../Vantage.App.Tests.csproj                  | 22 +++++++++++
 4 files changed, 105 insertions(+)
 create mode 100644 tests/Vantage.App.Tests/Fakes/StubProviders.cs
 create mode 100644 tests/Vantage.App.Tests/HeadlessTestApp.cs
 create mode 100644 tests/Vantage.App.Tests/HeadlessWindowTests.cs
 create mode 100644 tests/Vantage.App.Tests/Vantage.App.Tests.csproj

diff --git a/tests/Vantage.App.Tests/Fakes/StubProviders.cs b/tests/Vantage.App.Tests/Fakes/StubProviders.cs
new file mode 100644
index 0000000..4b9ffbb
--- /dev/null
+++ b/tests/Vantage.App.Tests/Fakes/StubProviders.cs
@@ -0,0 +1,31 @@
+using Vantage.Core.Health;
+using Vantage.Core.Metrics;
+using Vantage.Core.Models;
+
+namespace Vantage.App.Tests.Fakes;
+
+public sealed class ThrowingMetricsProvider : IMetricsProvider
+{
+    public const string Message = "host unreachable";
+
+    public Task<HostMetrics> GetMetricsAsync(HostConfig host, CancellationToken cancellationToken) =>
+        throw new InvalidOperationException(Message);
+}
+
+public sealed class FakeHealthChecker : IHealthChecker
+{
+    private readonly HealthCheckResult result;
+
+    public FakeHealthChecker(HealthCheckResult result)
+    {
+        this.result = result;
+    }
+
+    public int Calls { get; private set; }
+
+    public Task<HealthCheckResult> CheckAsync(HealthCheckConfig check, CancellationToken cancellationToken)
+    {
+        Calls++;
+        return Task.FromResult(result);
+    }
+}
diff --git a/tests/Vantage.App.Tests/HeadlessTestApp.cs b/tests/Vantage.App.Tests/HeadlessTestApp.cs
new file mode 100644
index 0000000..88b6e95
--- /dev/null
+++ b/tests/Vantage.App.Tests/HeadlessTestApp.cs
@@ -0,0 +1,15 @@
+using Avalonia;
+using Avalonia.Headless;
+using Vantage.App;
+using Vantage.App.Tests;
+
+[assembly: AvaloniaTestApplication(typeof(HeadlessTestApp))]
+
+namespace Vantage.App.Tests;
+
+public static class HeadlessTestApp
+{
+    public static AppBuilder BuildAvaloniaApp() => AppBuilder
+        .Configure<App>()
+        .UseHeadless(new AvaloniaHeadlessPlatformOptions());
+}
diff --git a/tests/Vantage.App.Tests/HeadlessWindowTests.cs b/tests/Vantage.App.Tests/HeadlessWindowTests.cs
new file mode 100644
index 0000000..46663cd
--- /dev/null
+++ b/tests/Vantage.App.Tests/HeadlessWindowTests.cs
@@ -0,0 +1,37 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Headless.XUnit;
+using Avalonia.VisualTree;
+using Microsoft.Extensions.DependencyInjection;
+using Vantage.App;
+using Vantage.App.ViewModels;
+using Vantage.App.Views;
+using Xunit;
+
+namespace Vantage.App.Tests;
+
+public class HeadlessWindowTests
+{
+    [AvaloniaFact]
+    public async Task MainWindow_LoadsXamlAndBindsViewModel()
+    {
+        var services = new ServiceCollection();
+        services.AddVantageApp(useMockProviders: true);
+        var provider = services.BuildServiceProvider();
+
+        var viewModel = provider.GetRequiredService<MainWindowViewModel>();
+        await viewModel.InitializeAsync();
+
+        var window = new MainWindow { DataContext = viewModel };
+        window.Show();
+
+        Assert.Same(viewModel, window.DataContext);
+        Assert.NotEmpty(viewModel.Hosts);
+
+        var tabControl = window.GetVisualDescendants().OfType<TabControl>().FirstOrDefault();
+        Assert.NotNull(tabControl);
+
+        var listBox = window.GetVisualDescendants().OfType<ListBox>().FirstOrDefault();
+        Assert.NotNull(listBox);
+    }
+}
diff --git a/tests/Vantage.App.Tests/Vantage.App.Tests.csproj b/tests/Vantage.App.Tests/Vantage.App.Tests.csproj
new file mode 100644
index 0000000..3a40616
--- /dev/null
+++ b/tests/Vantage.App.Tests/Vantage.App.Tests.csproj
@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <LangVersion>latest</LangVersion>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="xunit" Version="2.6.6" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.6" />
+    <PackageReference Include="Avalonia.Headless.XUnit" Version="11.0.10" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\Vantage.App\Vantage.App.csproj" />
+  </ItemGroup>
+
+</Project>