Fix Metadata delegation in DelegatingMcpServerTool/Prompt/Resource (#1338)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>
Co-authored-by: jeffhandley <1031940+jeffhandley@users.noreply.github.com>

tests/ModelContextProtocol.Tests/Server/DelegatingMcpServerResourceTests.cs

@@ -0,0 +1,63 @@
+using ModelContextProtocol.Protocol;
+using ModelContextProtocol.Server;
+using System.Reflection;
+
+namespace ModelContextProtocol.Tests.Server;
+
+public class DelegatingMcpServerResourceTests
+{
+    [Fact]
+    public void Ctor_NullInnerResource_Throws()
+    {
+        Assert.Throws<ArgumentNullException>("innerResource", () => new TestDelegatingResource(null!));
+    }
+
+    [Fact]
+    public async Task AllMembers_DelegateToInnerResource()
+    {
+        ResourceTemplate expectedTemplate = new() { Name = "sentinel-resource", UriTemplate = "test://resource" };
+        Resource expectedResource = new() { Name = "sentinel-resource", Uri = "test://resource" };
+        IReadOnlyList<object> expectedMetadata = new object[] { "m1" };
+        ReadResourceResult expectedResult = new() { Contents = [] };
+        InnerResource inner = new(expectedTemplate, expectedResource, expectedMetadata, expectedResult);
+
+        TestDelegatingResource delegating = new(inner);
+
+        Assert.Same(expectedTemplate, delegating.ProtocolResourceTemplate);
+        Assert.Same(expectedResource, delegating.ProtocolResource);
+        Assert.Same(expectedMetadata, delegating.Metadata);
+        Assert.True(delegating.IsMatch("test://resource"));
+        Assert.Same(expectedResult, await delegating.ReadAsync(null!, CancellationToken.None));
+        Assert.Equal(inner.ToString(), delegating.ToString());
+    }
+
+    [Fact]
+    public void OverridesAllVirtualAndAbstractMembers()
+    {
+        MethodInfo[] baseMethods = typeof(McpServerResource).GetMethods(BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly)
+            .Where(m => m.IsVirtual || m.IsAbstract)
+            .ToArray();
+
+        Assert.NotEmpty(baseMethods);
+
+        foreach (MethodInfo baseMethod in baseMethods)
+        {
+            Assert.True(
+                typeof(DelegatingMcpServerResource).GetMethods(BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly)
+                    .Any(m => m.Name == baseMethod.Name),
+                $"DelegatingMcpServerResource does not override {baseMethod.Name} from McpServerResource.");
+        }
+    }
+
+    private sealed class TestDelegatingResource(McpServerResource innerResource) : DelegatingMcpServerResource(innerResource);
+
+    private sealed class InnerResource(ResourceTemplate protocolResourceTemplate, Resource protocolResource, IReadOnlyList<object> metadata, ReadResourceResult result) : McpServerResource
+    {
+        public override ResourceTemplate ProtocolResourceTemplate => protocolResourceTemplate;
+        public override Resource? ProtocolResource => protocolResource;
+        public override IReadOnlyList<object> Metadata => metadata;
+        public override bool IsMatch(string uri) => true;
+        public override ValueTask<ReadResourceResult> ReadAsync(RequestContext<ReadResourceRequestParams> request, CancellationToken cancellationToken = default) => new(result);
+        public override string ToString() => "inner-resource";
+    }
+}