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Tighten draft protocol negotiation boundaries (#1692)

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Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Tarek Mahmoud Sayed <tarekms@ntdev.microsoft.com>
This commit is contained in:
Stephen Halter 2026-07-12 14:30:49 -07:00 • committed by GitHub
commit fd38f51e27
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1 changed files with 1755 additions and 589 deletions
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34
tests/ModelContextProtocol.Tests/Client/July2026ProtocolConnectionTests.cs
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@ -9,12 +9,12 @@ namespace ModelContextProtocol.Tests.Client;
/// <summary>
/// Connection-flow tests for the 2026-07-28 protocol revision (SEP-2575 + SEP-2567)
/// on <see cref="McpClient"/>. A client that requests
/// <see cref="McpHttpHeaders.July2026ProtocolVersion"/> calls <c>server/discover</c> rather than
/// <see cref="McpProtocolVersions.July2026ProtocolVersion"/> calls <c>server/discover</c> rather than
/// <c>initialize</c>.
/// </summary>
public class July2026ProtocolConnectionTests : ClientServerTestBase
{
private const string LatestStableVersion = "2025-11-25";
private const string LatestStableVersion = McpProtocolVersions.November2025ProtocolVersion;
public July2026ProtocolConnectionTests(ITestOutputHelper testOutputHelper)
: base(testOutputHelper, startServer: false)
@ -34,42 +34,40 @@ public class July2026ProtocolConnectionTests : ClientServerTestBase
{
StartServer();
var options = new McpClientOptions { ProtocolVersion = McpHttpHeaders.July2026ProtocolVersion };
var options = new McpClientOptions { ProtocolVersion = McpProtocolVersions.July2026ProtocolVersion };
await using var client = await CreateMcpClientForServer(options);
Assert.Equal(McpHttpHeaders.July2026ProtocolVersion, client.NegotiatedProtocolVersion);
Assert.Equal(McpProtocolVersions.July2026ProtocolVersion, client.NegotiatedProtocolVersion);
Assert.NotNull(client.ServerCapabilities);
Assert.Equal(nameof(July2026ProtocolConnectionTests), client.ServerInfo.Name);
}
[Fact]
public async Task Client_RequestingLegacyVersion_NegotiatesLegacy()
public async Task Client_RequestingInitializeHandshakeVersion_NegotiatesIt()
{
StartServer();
await using var client = await CreateMcpClientForServer(new McpClientOptions { ProtocolVersion = LatestStableVersion });
Assert.NotEqual(McpHttpHeaders.July2026ProtocolVersion, client.NegotiatedProtocolVersion);
Assert.NotEqual(McpProtocolVersions.July2026ProtocolVersion, client.NegotiatedProtocolVersion);
}
[Fact]
public async Task LegacyClient_CanCallServerDiscover()
public async Task InitializeHandshakeClient_CannotCallServerDiscover()
{
// server/discover is registered unconditionally, so a legacy client can probe it
// (e.g., to learn capabilities without doing a second initialize).
// server/discover is registered unconditionally so the protocol boundary filter can return a structured
// error, but initialize-handshake clients cannot use it after negotiating an older protocol version.
StartServer();
await using var client = await CreateMcpClientForServer(new McpClientOptions { ProtocolVersion = LatestStableVersion });
var response = await client.SendRequestAsync(
new JsonRpcRequest { Method = RequestMethods.ServerDiscover },
TestContext.Current.CancellationToken);
var exception = await Assert.ThrowsAsync<McpProtocolException>(async () =>
await client.SendRequestAsync(
new JsonRpcRequest { Method = RequestMethods.ServerDiscover },
TestContext.Current.CancellationToken));
var discoverResult = JsonSerializer.Deserialize<DiscoverResult>(response.Result, McpJsonUtilities.DefaultOptions);
Assert.NotNull(discoverResult);
Assert.NotEmpty(discoverResult.SupportedVersions);
Assert.Contains(LatestStableVersion, discoverResult.SupportedVersions);
Assert.Equal(nameof(July2026ProtocolConnectionTests), discoverResult.ServerInfo.Name);
Assert.Equal(McpErrorCode.MethodNotFound, exception.ErrorCode);
Assert.Contains(RequestMethods.ServerDiscover, exception.Message, StringComparison.Ordinal);
}
[Fact]
@ -85,6 +83,6 @@ public class July2026ProtocolConnectionTests : ClientServerTestBase
var discoverResult = JsonSerializer.Deserialize<DiscoverResult>(response.Result, McpJsonUtilities.DefaultOptions);
Assert.NotNull(discoverResult);
Assert.Contains(McpHttpHeaders.July2026ProtocolVersion, discoverResult.SupportedVersions);
Assert.Equal([McpProtocolVersions.July2026ProtocolVersion], discoverResult.SupportedVersions);
}
}