Add stateless test

Author: stephentoub

src/ModelContextProtocol/Server/McpServerExtensions.cs

@@ -258,7 +258,7 @@ private static void ThrowIfElicitationUnsupported(IMcpServer server)
         {
             if (server.ServerOptions.KnownClientInfo is not null)
             {
-                throw new InvalidOperationException("Elicititation requests are not supported in stateless mode.");
+                throw new InvalidOperationException("Elicitation is not supported in stateless mode.");
             }
 
             throw new InvalidOperationException("Client does not support elicitation requests.");

tests/ModelContextProtocol.AspNetCore.Tests/StatelessServerTests.cs

@@ -136,6 +136,26 @@ public async Task RootsRequest_Fails_WithInvalidOperationException()
         Assert.Equal("Server to client requests are not supported in stateless mode.", toolContent.Text);
     }
 
+    [Fact]
+    public async Task ElicitRequest_Fails_WithInvalidOperationException()
+    {
+        await StartAsync();
+
+        var mcpClientOptions = new McpClientOptions();
+        mcpClientOptions.Capabilities = new();
+        mcpClientOptions.Capabilities.Elicitation ??= new();
+        mcpClientOptions.Capabilities.Elicitation.ElicitationHandler = (_, _) =>
+        {
+            throw new UnreachableException();
+        };
+
+        await using var client = await ConnectMcpClientAsync(mcpClientOptions);
+
+        var toolResponse = await client.CallToolAsync("testElicitationErrors", cancellationToken: TestContext.Current.CancellationToken);
+        var toolContent = Assert.Single(toolResponse.Content);
+        Assert.Equal("Server to client requests are not supported in stateless mode.", toolContent.Text);
+    }
+
     [Fact]
     public async Task UnsolicitedNotification_Fails_WithInvalidOperationException()
     {
@@ -206,6 +226,21 @@ public static async Task<string> TestRootsErrors(IMcpServer server)
         return ex.Message;
     }
 
+    [McpServerTool(Name = "testElicitationErrors")]
+    public static async Task<string> TestElicitationErrors(IMcpServer server)
+    {
+        const string expectedElicitationErrorMessage = "Elicitation is not supported in stateless mode.";
+
+        // Even when the client has elicitation support, it should not be advertised in stateless mode.
+        Assert.Null(server.ClientCapabilities);
+
+        var requestElicitationEx = Assert.Throws<InvalidOperationException>(() => server.ElicitAsync(new()));
+        Assert.Equal(expectedElicitationErrorMessage, requestElicitationEx.Message);
+
+        var ex = await Assert.ThrowsAsync<InvalidOperationException>(() => server.SendRequestAsync(new JsonRpcRequest { Method = RequestMethods.ElicitationCreate }));
+        return ex.Message;
+    }
+
     [McpServerTool(Name = "testScope")]
     public static string? TestScope(ScopedService scopedService) => scopedService.State;