deepseek-harness/packages/mcp/mcp-client/tests/fixture-server.ts

/**
 * Minimal MCP server over stdio for e2e testing of the dsh-mcp-client plugin.
 * Registers controlled tools with predictable behavior for asserting edge cases.
 *
 * Run: node fixture-server.ts
 */

import { McpServer, type CallToolResult } from '@modelcontextprotocol/server'
import { serveStdio } from '@modelcontextprotocol/server/stdio'
import { z } from 'zod'

function createFixtureServer(): McpServer {
  const server = new McpServer(
    { name: 'fixture-server', version: '1.0.0' },
    { capabilities: { tools: { listChanged: true } } },
  )

  server.registerTool('add', {
    title: 'Add Tool',
    description: 'Adds two numbers.',
    inputSchema: z.object({ a: z.number().describe('First number'), b: z.number().describe('Second number') }),
  }, async args => ({
    content: [{ type: 'text', text: String(args.a + args.b) }],
  }))

  server.registerTool('greet', {
    title: 'Greet Tool',
    description: 'Greets a person by name.',
    inputSchema: z.object({ name: z.string().describe('Name to greet') }),
  }, async args => ({
    content: [{ type: 'text', text: `Hello, ${args.name}!` }],
  }))

  server.registerTool('fail', {
    title: 'Fail Tool',
    description: 'Always returns an error.',
    inputSchema: z.object({}),
  }, async (): Promise<CallToolResult> => ({
    content: [{ type: 'text', text: 'Something went wrong' }],
    isError: true,
  }))

  server.registerTool('image', {
    title: 'Image Tool',
    description: 'Returns an image content block.',
    inputSchema: z.object({}),
  }, async (): Promise<CallToolResult> => ({
    content: [
      { type: 'text', text: 'Here is an image:' },
      { type: 'image', data: 'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVR4nGP4z8AAAAMBAQDJ/pLvAAAAAElFTkSuQmCC', mimeType: 'image/png' },
      { type: 'text', text: 'End of image.' },
    ],
  }))

  server.registerTool('crash', {
    title: 'Crash Tool',
    description: 'Replies, then exits the server process (crash-recovery test).',
    inputSchema: z.object({}),
  }, async (): Promise<CallToolResult> => {
    // Exit AFTER the response flushes so the caller observes a clean result
    // followed by a transport close, like a real post-reply crash.
    setTimeout(() => process.exit(7), 25)
    return { content: [{ type: 'text', text: 'crashing' }] }
  })

  // Dotted name: legal in MCP, illegal in the DeepSeek function-name contract.
  // Exercises the bridge's normalize-and-hash public-name path end to end.
  server.registerTool('admin.reset', {
    title: 'Admin Reset Tool',
    description: 'Tool with a dotted name (normalization test).',
    inputSchema: z.object({}),
  }, async (): Promise<CallToolResult> => ({
    content: [{ type: 'text', text: 'reset done' }],
  }))
  return server
}

serveStdio(createFixtureServer)