Add MCP conformance test coverage

[skarpovdev]

Motivation and Context

1. The currently failing checks are commented out in ConformanceTest, see the TODOs.
2. I added detailed logging for Gradle task, Server, and Client to allow easier output reading when viewing tests results outside of IDE.
3. As a future improvement, instead of hard-coding scenarios, we can get them with npx @modelcontextprotocol/conformance list and run all of them.
4. The conformance framework writes its result into kotlin-sdk-test/results directory and contains JSONs like the one below:

[
  {
    "id": "mcp-client-initialization",
    "name": "MCPClientInitialization",
    "description": "Validates that MCP client properly initializes with server",
    "status": "SUCCESS",
    "timestamp": "2025-11-28T14:38:36.718Z",
    "specReferences": [
      {
        "id": "MCP-Lifecycle",
        "url": "https://modelcontextprotocol.io/specification/2025-06-18/basic/lifecycle"
      }
    ],
    "details": {
      "protocolVersionSent": "2025-06-18",
      "expectedSpecVersion": "2025-06-18",
      "versionMatch": true,
      "clientName": "kotlin-conformance-client",
      "clientVersion": "1.0.0"
    }
  },
  {
    "id": "server-info",
    "name": "ServerInfo",
    "description": "Test server info returned to client",
    "status": "INFO",
    "timestamp": "2025-11-28T14:38:36.718Z",
    "specReferences": [
      {
        "id": "MCP-Lifecycle",
        "url": "https://modelcontextprotocol.io/specification/2025-06-18/basic/lifecycle"
      }
    ],
    "details": {
      "serverName": "test-server",
      "serverVersion": "1.0.0"
    }
  }
]

As another future improvement, we can do somethig with these JSON files, like putting them into a job summary on GitHub.

5. The client test also generated stderr.txt file in kotlin-sdk-test/results/initialize-....... which contains errors because it tries to call a tool. I haven't investigated if it's just the way I wrote the client or related to StreamableHttpClientTransport.
6. The server is the simplified version of the existing server for Kotlin<--->Typescript tests. If conformance tests extend significantly, we can either combine the server implementations or ditch the integration tests.

How Has This Been Tested?

Breaking Changes

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[Copilot]

Pull request overview

This PR adds comprehensive MCP (Model Context Protocol) conformance test coverage to the Kotlin SDK. The implementation includes a test server, test client, and a test harness that integrates with the official @modelcontextprotocol/conformance testing framework from npm.

Key Changes

• Created a conformance test framework with dynamic JUnit tests for both server and client scenarios
• Implemented an HTTP-based MCP test server using Ktor with SSE support for streaming
• Added a conformance test client that validates MCP protocol compliance
• Integrated conformance testing into the CI/CD pipeline with artifact collection

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
kotlin-sdk-test/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/conformance/ConformanceTest.kt	Test harness that launches the conformance server and runs both server and client test scenarios using the official conformance tool
kotlin-sdk-test/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/conformance/ConformanceServer.kt	HTTP-based MCP server implementation with session management, SSE streaming, and test resources (tools, prompts, resources)
kotlin-sdk-test/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/conformance/ConformanceClient.kt	MCP client implementation that connects to test servers and validates tool calling functionality
kotlin-sdk-test/build.gradle.kts	Adds custom Gradle task for running conformance tests with detailed logging and test classpath configuration
.gitignore	Excludes conformance test results directory from version control
.github/workflows/build.yml	Integrates conformance tests into CI pipeline with Node.js setup and artifact upload for test results

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[kpavlov]

@skarpovdev, Thank you! It's cool to have these tests running!

I see ConformanceTest is running as a part of :kotlin-sdk-test:jvmTest. Did you consider creating a different module/source root and/or excluding ConformanceTest from the everyday jvmRun task?

Would it also make sense to create different ConformanceClient/Server for other protocols?

I'm okay with it being done in a follow-up PR

[skarpovdev]

I see ConformanceTest is running as a part of :kotlin-sdk-test:jvmTest. Did you consider creating a different module/source root and/or excluding ConformanceTest from the everyday jvmRun task?

Good point, I'll exclude them from other tests move them to a separate module.

Would it also make sense to create different ConformanceClient/Server for other protocols?

Will do in this PR while I'm in the context.

[skarpovdev]

Looking at conformance/src/scenarios/server/client-helper.ts the conformance framework doesn't support anything else const transport = new StreamableHTTPClientTransport(new URL(serverUrl));.
It doesn't support testing Stdio since it requires --url parameter and at the same time doesn't have --command option for server testing, so to test Stdio we would probably have to wrap it in another transport layer.
I left WebSocket one hoping it may work in near future, but Stdio seems unlikely to be covered by conformance framework.

[kpavlov]

LGTM