Added some tests to validate endpoint metadata extraction

Author: mkArtakMSFT

src/Mvc/Mvc.Core/src/ApplicationModels/DefaultApplicationModelProvider.cs

@@ -355,11 +355,10 @@ internal PropertyModel CreatePropertyModel(PropertyInfo propertyInfo)
 
         AddReturnTypeMetadata(actionModel.Selectors, methodInfo);
 
-
         return actionModel;
     }
 
-    private static void AddReturnTypeMetadata(IList<SelectorModel> selectors, MethodInfo methodInfo)
+    internal static void AddReturnTypeMetadata(IList<SelectorModel> selectors, MethodInfo methodInfo)
     {
         // Get metadata from return type
         var returnType = methodInfo.ReturnType;

src/Mvc/Mvc.Core/test/ApplicationModels/DefaultApplicationModelProviderTest.cs

@@ -1243,6 +1243,45 @@ public void CreateActionModel_InheritedAttributeRoutesOverridden()
         Assert.Contains(selectorModel.AttributeRouteModel.Attribute, action.Attributes);
     }
 
+    [Fact]
+    public void CreateActionModel_PopulatesReturnTypeEndpointMetadata() {
+        // Arrange
+        var builder = new TestApplicationModelProvider();
+        var typeInfo = typeof(TypedResultsReturningActionsController).GetTypeInfo();
+        var actionName = nameof(TypedResultsReturningActionsController.Get);
+
+        // Act
+        var action = builder.CreateActionModel(typeInfo, typeInfo.AsType().GetMethod(actionName));
+
+        // Assert
+        Assert.NotNull(action.Selectors);
+        Assert.All(action.Selectors, selector =>
+        {
+            Assert.NotNull(selector.EndpointMetadata);
+            Assert.Contains(selector.EndpointMetadata, m => m is ProducesResponseTypeMetadata);
+        });
+        var metadata = action.Selectors[0].EndpointMetadata.OfType<ProducesResponseTypeMetadata>().Single();
+        Assert.Equal(200, metadata.StatusCode);
+    }
+
+    [Fact]
+    public void AddReturnTypeMetadata_ExtractsMetadataFromReturnType()
+    {
+        // Arrange
+        var selector = new SelectorModel();
+        var selectors = new List<SelectorModel> { selector };
+        var actionMethod = typeof(TypedResultsReturningActionsController).GetMethod(nameof(TypedResultsReturningActionsController.Get));
+
+        // Act
+        DefaultApplicationModelProvider.AddReturnTypeMetadata(selectors, actionMethod);
+
+        // Assert
+        Assert.NotNull(selector.EndpointMetadata);
+        Assert.Single(selector.EndpointMetadata);
+        Assert.IsType<ProducesResponseTypeMetadata>(selector.EndpointMetadata.Single()); 
+        Assert.Equal(200, ((ProducesResponseTypeMetadata)selector.EndpointMetadata[0]).StatusCode);
+    }
+
     [Fact]
     public void ControllerDispose_ExplicitlyImplemented_IDisposableMethods_AreTreatedAs_NonActions()
     {
@@ -1711,6 +1750,16 @@ public void Details() { }
         public void List() { }
     }
 
+    private class TypedResultsReturningActionsController : Controller
+    {
+        [HttpGet]
+        public Http.HttpResults.Ok<Foo> Get() => TypedResults.Ok<Foo>(new Foo { Info = "Hello" });
+    }
+
+    public class Foo {
+        public required string Info { get; set; }
+    }
+
     private class CustomHttpMethodsAttribute : Attribute, IActionHttpMethodProvider
     {
         private readonly string[] _methods;

src/Mvc/Mvc.Core/test/Microsoft.AspNetCore.Mvc.Core.Test.csproj

@@ -12,6 +12,7 @@
   <ItemGroup>
     <Reference Include="FSharp.Core" />
     <Reference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" />
+    <Reference Include="Microsoft.AspNetCore.Http.Results" />
     <ProjectReference Include="..\..\shared\Mvc.Core.TestCommon\Microsoft.AspNetCore.Mvc.Core.TestCommon.csproj" />
     <ProjectReference Include="..\..\shared\Mvc.TestDiagnosticListener\Microsoft.AspNetCore.Mvc.TestDiagnosticListener.csproj" />