Use DOTNET_STARTUP_HOOK to have the target run the tests (#91)

WoofWare.NUnitTestRunner.StartupHook/StartupHook.cs

@@ -0,0 +1,35 @@
+using System.Linq;
+using System.Reflection;
+using System.Runtime.Loader;
+using WoofWare.NUnitTestRunner.StartupHook;
+
+namespace WoofWare.NUnitTestRunner.StartupHook
+{
+    internal class StartupAssemblyLoadContext : AssemblyLoadContext
+    {
+        private readonly AssemblyDependencyResolver _resolver;
+
+        public StartupAssemblyLoadContext()
+        {
+            _resolver = new AssemblyDependencyResolver(Assembly.GetExecutingAssembly().Location);
+        }
+
+        protected override Assembly Load(AssemblyName assemblyName)
+        {
+            var assemblyPath = _resolver.ResolveAssemblyToPath(assemblyName);
+
+            return assemblyPath != null ? LoadFromAssemblyPath(assemblyPath) : null;
+        }
+    }
+}
+
+// Must be internal and called `StartupHook`
+internal class StartupHook
+{
+    public static void Initialize()
+    {
+        var loadContext = new StartupAssemblyLoadContext();
+        var assembly = loadContext.LoadFromAssemblyName(new AssemblyName("WoofWare.NUnitTestRunner.StartupHookLogic"));
+        assembly.DefinedTypes.First(x => x.Name == "StartupHookLogic").GetDeclaredMethod("DoIt")!.Invoke(null, null);
+    }
+}