CastRootScopeFrame expression should be casting scope.Root, instead o…

…f scope to the target type

src/Lamar.Testing/Bugs/Bug_385_ServiceScopeFactory_is_not_root.cs

@@ -0,0 +1,33 @@
+namespace Lamar.Testing.Bugs;
+
+using Microsoft.Extensions.DependencyInjection;
+using Shouldly;
+using Xunit;
+
+public class Bug_385_ServiceScopeFactory_is_not_root
+{
+    [Fact]
+    public void Test()
+    {
+        var container = Container.For(x =>
+        {
+            x.Use<TestService>();
+        });
+
+        var serviceScopeFactory = container.GetInstance<IServiceScopeFactory>();
+        using var scope = serviceScopeFactory.CreateScope();
+        var testService = scope.ServiceProvider.GetRequiredService<TestService>();
+
+        testService.ServiceScopeFactory.ShouldBe(serviceScopeFactory);
+    }
+
+    public class TestService
+    {
+        public IServiceScopeFactory ServiceScopeFactory { get; }
+
+        public TestService(IServiceScopeFactory serviceScopeFactory)
+        {
+            ServiceScopeFactory = serviceScopeFactory;
+        }
+    }
+}

src/Lamar/IoC/Resolvers/ScopeInstance.cs

@@ -54,8 +54,12 @@ public CastRootScopeFrame(Type interfaceType)
     public void WriteExpressions(LambdaDefinition definition)
     {
         var variableExpr = definition.RegisterExpression(Variable);
-        definition.Body.Add(Expression.Assign(variableExpr,
-            Expression.Convert(definition.ExpressionFor(_scope), Variable.VariableType)));
+
+        var root = Expression.Property(definition.ExpressionFor(_scope), nameof(Scope.Root));
+        var convert = Expression.Convert(root, Variable.VariableType);
+        var assign = Expression.Assign(variableExpr, convert);
+
+        definition.Body.Add(assign);
     }
 
     public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)