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Follow-ups to #1610: de-draft 2026-07-28 terminology, renumber error codes, ProtocolVersion floor (#1671)

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Stephen Halter 2026-06-25 14:07:52 -07:00 • committed by GitHub
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tests/ModelContextProtocol.AspNetCore.Tests/July2026ProtocolHttpHandlerTests.cs Normal file
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using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using ModelContextProtocol.AspNetCore.Tests.Utils;
using ModelContextProtocol.Protocol;
using System.Net;
using System.Text;
using System.Text.Json;
namespace ModelContextProtocol.AspNetCore.Tests;
/// <summary>
/// HTTP-level tests for the 2026-07-28 protocol revision (SEP-2575 + SEP-2567): verify that the server
/// suppresses the <c>Mcp-Session-Id</c> header for those requests and returns structured
/// <see cref="McpErrorCode.UnsupportedProtocolVersion"/> errors instead of plain 400s.
/// </summary>
public class July2026ProtocolHttpHandlerTests(ITestOutputHelper outputHelper) : KestrelInMemoryTest(outputHelper), IAsyncDisposable
{
private WebApplication? _app;
private async Task StartAsync(bool stateless = false)
{
Builder.Services.AddMcpServer(options =>
{
options.ServerInfo = new Implementation { Name = nameof(July2026ProtocolHttpHandlerTests), Version = "1" };
}).WithHttpTransport(options =>
{
// Stateless = false maps the GET/DELETE endpoints and opts the author into sessions. Starting with
// the 2026-07-28 protocol revision, Streamable HTTP no longer supports sessions, so such a request is
// refused on a session-enabled server. Stateless = true (the default) serves them natively.
options.Stateless = stateless;
});
_app = Builder.Build();
_app.MapMcp();
await _app.StartAsync(TestContext.Current.CancellationToken);
HttpClient.DefaultRequestHeaders.Accept.Add(new("application/json"));
HttpClient.DefaultRequestHeaders.Accept.Add(new("text/event-stream"));
}
public async ValueTask DisposeAsync()
{
if (_app is not null)
{
await _app.DisposeAsync();
}
base.Dispose();
}
[Fact]
public async Task Request_OnStatelessServer_Succeeds_WithoutMcpSessionIdHeader()
{
await StartAsync(stateless: true);
HttpClient.DefaultRequestHeaders.Add("MCP-Protocol-Version", McpHttpHeaders.July2026ProtocolVersion);
HttpClient.DefaultRequestHeaders.Add("Mcp-Method", "server/discover");
// On a stateless server, server/discover succeeds without creating a session.
var content = new StringContent(
"""{"jsonrpc":"2.0","id":1,"method":"server/discover","params":{}}""",
Encoding.UTF8, "application/json");
using var response = await HttpClient.PostAsync("", content, TestContext.Current.CancellationToken);
Assert.Equal(HttpStatusCode.OK, response.StatusCode);
Assert.False(response.Headers.Contains("Mcp-Session-Id"), "Responses on the 2026-07-28 revision must not include Mcp-Session-Id");
}
[Fact]
public async Task Request_OnStatefulServer_IsRefused_WithUnsupportedProtocolVersionError()
{
// Starting with the 2026-07-28 protocol revision, Streamable HTTP no longer supports sessions (SEP-2567),
// so the server cannot honor it when configured with sessions (Stateless = false). The server refuses that
// version with UnsupportedProtocolVersion (excluding it from Supported) so a dual-era client falls back
// to the legacy initialize handshake.
await StartAsync(stateless: false);
HttpClient.DefaultRequestHeaders.Add("MCP-Protocol-Version", McpHttpHeaders.July2026ProtocolVersion);
HttpClient.DefaultRequestHeaders.Add("Mcp-Method", "server/discover");
var content = new StringContent(
"""{"jsonrpc":"2.0","id":1,"method":"server/discover","params":{}}""",
Encoding.UTF8, "application/json");
using var response = await HttpClient.PostAsync("", content, TestContext.Current.CancellationToken);
Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
Assert.False(response.Headers.Contains("Mcp-Session-Id"));
var body = await response.Content.ReadAsStringAsync(TestContext.Current.CancellationToken);
var rpcMessage = JsonSerializer.Deserialize<JsonRpcMessage>(body, McpJsonUtilities.DefaultOptions);
var rpcError = Assert.IsType<JsonRpcError>(rpcMessage);
Assert.Equal((int)McpErrorCode.UnsupportedProtocolVersion, rpcError.Error.Code);
var dataElement = (JsonElement)rpcError.Error.Data!;
var errorData = dataElement.Deserialize<UnsupportedProtocolVersionErrorData>(McpJsonUtilities.DefaultOptions);
Assert.NotNull(errorData);
Assert.Equal(McpHttpHeaders.July2026ProtocolVersion, errorData.Requested);
// The 2026-07-28 protocol version is excluded from Supported so the client downgrades to a legacy version.
Assert.NotEmpty(errorData.Supported);
Assert.DoesNotContain(McpHttpHeaders.July2026ProtocolVersion, errorData.Supported);
}
[Fact]
public async Task RequestWithUnsupportedProtocolVersion_Returns_UnsupportedProtocolVersionError()
{
await StartAsync();
HttpClient.DefaultRequestHeaders.Add("MCP-Protocol-Version", "2099-12-31");
HttpClient.DefaultRequestHeaders.Add("Mcp-Method", "server/discover");
var content = new StringContent(
"""{"jsonrpc":"2.0","id":1,"method":"server/discover","params":{}}""",
Encoding.UTF8, "application/json");
using var response = await HttpClient.PostAsync("", content, TestContext.Current.CancellationToken);
Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
var body = await response.Content.ReadAsStringAsync(TestContext.Current.CancellationToken);
var rpcMessage = JsonSerializer.Deserialize<JsonRpcMessage>(body, McpJsonUtilities.DefaultOptions);
var rpcError = Assert.IsType<JsonRpcError>(rpcMessage);
Assert.Equal((int)McpErrorCode.UnsupportedProtocolVersion, rpcError.Error.Code);
// Validate the structured data payload (SEP-2575 §"Unsupported Protocol Versions").
var dataElement = (JsonElement)rpcError.Error.Data!;
var errorData = dataElement.Deserialize<UnsupportedProtocolVersionErrorData>(McpJsonUtilities.DefaultOptions);
Assert.NotNull(errorData);
Assert.Equal("2099-12-31", errorData.Requested);
Assert.NotEmpty(errorData.Supported);
}
[Fact]
public async Task Request_WithMcpSessionIdHeader_IsRejected()
{
// Starting with the 2026-07-28 protocol revision, Streamable HTTP no longer supports sessions (SEP-2567):
// a request carrying an Mcp-Session-Id is non-conformant and is rejected with 400 regardless of the
// Stateless setting.
await StartAsync();
HttpClient.DefaultRequestHeaders.Add("MCP-Protocol-Version", McpHttpHeaders.July2026ProtocolVersion);
HttpClient.DefaultRequestHeaders.Add("Mcp-Method", "server/discover");
HttpClient.DefaultRequestHeaders.Add("Mcp-Session-Id", "non-existent-session-id");
var content = new StringContent(
"""{"jsonrpc":"2.0","id":1,"method":"server/discover","params":{}}""",
Encoding.UTF8, "application/json");
using var response = await HttpClient.PostAsync("", content, TestContext.Current.CancellationToken);
Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
}
[Fact]
public async Task Get_WithoutSessionId_IsRejected()
{
await StartAsync();
HttpClient.DefaultRequestHeaders.Add("MCP-Protocol-Version", McpHttpHeaders.July2026ProtocolVersion);
using var response = await HttpClient.GetAsync("", TestContext.Current.CancellationToken);
Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
}
[Fact]
public async Task Get_WithSessionId_IsRejected()
{
await StartAsync();
HttpClient.DefaultRequestHeaders.Add("MCP-Protocol-Version", McpHttpHeaders.July2026ProtocolVersion);
HttpClient.DefaultRequestHeaders.Add("Mcp-Session-Id", "non-existent-session-id");
using var response = await HttpClient.GetAsync("", TestContext.Current.CancellationToken);
Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
}
[Fact]
public async Task Delete_WithoutSessionId_IsRejected()
{
await StartAsync();
HttpClient.DefaultRequestHeaders.Add("MCP-Protocol-Version", McpHttpHeaders.July2026ProtocolVersion);
using var response = await HttpClient.DeleteAsync("", TestContext.Current.CancellationToken);
Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
}
[Fact]
public async Task Delete_WithSessionId_IsRejected()
{
await StartAsync();
HttpClient.DefaultRequestHeaders.Add("MCP-Protocol-Version", McpHttpHeaders.July2026ProtocolVersion);
HttpClient.DefaultRequestHeaders.Add("Mcp-Session-Id", "non-existent-session-id");
using var response = await HttpClient.DeleteAsync("", TestContext.Current.CancellationToken);
Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
}
}