Fix discovery of endpoint metadata from async route handlers (#41388)

Fixes #41384

Co-authored-by: Damian Edwards <[email protected]>

Author: github-actions[bot]

src/Http/Http.Extensions/src/RequestDelegateFactory.cs

@@ -406,13 +406,19 @@ private static void AddTypeProvidedMetadata(MethodInfo methodInfo, List<object>
         }
 
         // Get metadata from return type
-        if (methodInfo.ReturnType is not null && typeof(IEndpointMetadataProvider).IsAssignableFrom(methodInfo.ReturnType))
+        var returnType = methodInfo.ReturnType;
+        if (AwaitableInfo.IsTypeAwaitable(returnType, out var awaitableInfo))
+        {
+            returnType = awaitableInfo.ResultType;
+        }
+
+        if (returnType is not null && typeof(IEndpointMetadataProvider).IsAssignableFrom(returnType))
         {
             // Return type implements IEndpointMetadataProvider
             var context = new EndpointMetadataContext(methodInfo, metadata, services);
             invokeArgs ??= new object[1];
             invokeArgs[0] = context;
-            PopulateMetadataForEndpointMethod.MakeGenericMethod(methodInfo.ReturnType).Invoke(null, invokeArgs);
+            PopulateMetadataForEndpointMethod.MakeGenericMethod(returnType).Invoke(null, invokeArgs);
         }
     }
 

src/Http/Http.Extensions/test/RequestDelegateFactoryTests.cs

@@ -5081,6 +5081,32 @@ public void Create_DiscoversEndpointMetadata_FromReturnTypeImplementingIEndpoint
         Assert.Contains(result.EndpointMetadata, m => m is CustomEndpointMetadata { Source: MetadataSource.ReturnType });
     }
 
+    [Fact]
+    public void Create_DiscoversEndpointMetadata_FromTaskWrappedReturnTypeImplementingIEndpointMetadataProvider()
+    {
+        // Arrange
+        var @delegate = () => Task.FromResult(new AddsCustomEndpointMetadataResult());
+
+        // Act
+        var result = RequestDelegateFactory.Create(@delegate);
+
+        // Assert
+        Assert.Contains(result.EndpointMetadata, m => m is CustomEndpointMetadata { Source: MetadataSource.ReturnType });
+    }
+
+    [Fact]
+    public void Create_DiscoversEndpointMetadata_FromValueTaskWrappedReturnTypeImplementingIEndpointMetadataProvider()
+    {
+        // Arrange
+        var @delegate = () => ValueTask.FromResult(new AddsCustomEndpointMetadataResult());
+
+        // Act
+        var result = RequestDelegateFactory.Create(@delegate);
+
+        // Assert
+        Assert.Contains(result.EndpointMetadata, m => m is CustomEndpointMetadata { Source: MetadataSource.ReturnType });
+    }
+
     [Fact]
     public void Create_CombinesDefaultMetadata_AndMetadataFromReturnTypesImplementingIEndpointMetadataProvider()
     {
@@ -5103,6 +5129,50 @@ public void Create_CombinesDefaultMetadata_AndMetadataFromReturnTypesImplementin
         Assert.Contains(result.EndpointMetadata, m => m is DefaultMetadataCountMetadata { Count: 2 });
     }
 
+    [Fact]
+    public void Create_CombinesDefaultMetadata_AndMetadataFromTaskWrappedReturnTypesImplementingIEndpointMetadataProvider()
+    {
+        // Arrange
+        var @delegate = () => Task.FromResult(new CountsDefaultEndpointMetadataResult());
+        var options = new RequestDelegateFactoryOptions
+        {
+            InitialEndpointMetadata = new List<object>
+            {
+                new CustomEndpointMetadata { Source = MetadataSource.Caller }
+            }
+        };
+
+        // Act
+        var result = RequestDelegateFactory.Create(@delegate, options);
+
+        // Assert
+        Assert.Contains(result.EndpointMetadata, m => m is CustomEndpointMetadata { Source: MetadataSource.Caller });
+        // Expecting '2' as only MethodInfo and initial metadata will be in the metadata list when this metadata item is added
+        Assert.Contains(result.EndpointMetadata, m => m is DefaultMetadataCountMetadata { Count: 2 });
+    }
+
+    [Fact]
+    public void Create_CombinesDefaultMetadata_AndMetadataFromValueTaskWrappedReturnTypesImplementingIEndpointMetadataProvider()
+    {
+        // Arrange
+        var @delegate = () => ValueTask.FromResult(new CountsDefaultEndpointMetadataResult());
+        var options = new RequestDelegateFactoryOptions
+        {
+            InitialEndpointMetadata = new List<object>
+            {
+                new CustomEndpointMetadata { Source = MetadataSource.Caller }
+            }
+        };
+
+        // Act
+        var result = RequestDelegateFactory.Create(@delegate, options);
+
+        // Assert
+        Assert.Contains(result.EndpointMetadata, m => m is CustomEndpointMetadata { Source: MetadataSource.Caller });
+        // Expecting '2' as only MethodInfo and initial metadata will be in the metadata list when this metadata item is added
+        Assert.Contains(result.EndpointMetadata, m => m is DefaultMetadataCountMetadata { Count: 2 });
+    }
+
     [Fact]
     public void Create_CombinesDefaultMetadata_AndMetadataFromParameterTypesImplementingIEndpointParameterMetadataProvider()
     {
@@ -5194,6 +5264,32 @@ public void Create_AllowsRemovalOfDefaultMetadata_ByReturnTypesImplementingIEndp
         Assert.DoesNotContain(result.EndpointMetadata, m => m is IAcceptsMetadata);
     }
 
+    [Fact]
+    public void Create_AllowsRemovalOfDefaultMetadata_ByTaskWrappedReturnTypesImplementingIEndpointMetadataProvider()
+    {
+        // Arrange
+        var @delegate = (Todo todo) => Task.FromResult(new RemovesAcceptsMetadataResult());
+
+        // Act
+        var result = RequestDelegateFactory.Create(@delegate);
+
+        // Assert
+        Assert.DoesNotContain(result.EndpointMetadata, m => m is IAcceptsMetadata);
+    }
+
+    [Fact]
+    public void Create_AllowsRemovalOfDefaultMetadata_ByValueTaskWrappedReturnTypesImplementingIEndpointMetadataProvider()
+    {
+        // Arrange
+        var @delegate = (Todo todo) => ValueTask.FromResult(new RemovesAcceptsMetadataResult());
+
+        // Act
+        var result = RequestDelegateFactory.Create(@delegate);
+
+        // Assert
+        Assert.DoesNotContain(result.EndpointMetadata, m => m is IAcceptsMetadata);
+    }
+
     [Fact]
     public void Create_AllowsRemovalOfDefaultMetadata_ByParameterTypesImplementingIEndpointParameterMetadataProvider()
     {