test: MCP server initialization function lacks unit test coverage

[jongio]

Summary

The runMCPServer() function in cli/src/cmd/exec/commands/mcp.go (lines 49-126) initializes the MCP server, registers all tool handlers, configures rate limiting, and starts the stdio transport. This function has zero direct test coverage.

Impact

• Server initialization logic (tool registration order, rate limit config, capability flags) is untested
• Regressions in server setup would only surface during manual or integration testing
• The function contains ~75 lines of non-trivial setup logic including error handling branches

Details

What is tested:

• Individual tool handlers (handleExecScript, handleExecInline, handleListShells, handleGetEnvironment) are well-tested in mcp_test.go
• buildShellArgs and marshalExecResult have thorough table-driven tests

What is NOT tested:

• Server builder configuration (lines 68-90): capability flags, server name/version
• Tool registration (lines 92-119): correct tool names, descriptions, input schemas
• Rate limiting setup (lines 85-87): rate limit values and behavior
• Error path when ServeStdio fails (line 121-123)
• The wiring between registered tool names and their handler functions

Recommendation

1. Extract the server builder configuration into a testable helper that returns the configured server (without calling ServeStdio)
2. Add unit tests that verify:
   • All expected tools are registered with correct names
   • Tool input schemas match expected structure
   • Server capabilities are correctly configured
3. Consider adding a lightweight integration test using an in-memory MCP transport (if the azdext SDK supports it) to verify end-to-end tool dispatch