Lorem Ipsum MCP Server

import { Client } from "@modelcontextprotocol/sdk/client/index.js"; import { SSEClientTransport } from "@modelcontextprotocol/sdk/client/sse.js"; import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js"; import { Server } from "@modelcontextprotocol/sdk/server/index.js"; import { EventSource } from "eventsource"; import { getRandomPort } from "get-port-please"; import { setTimeout as delay } from "node:timers/promises"; import { expect, it, vi } from "vitest"; import { proxyServer } from "./proxyServer.js"; import { startSSEServer } from "./startSSEServer.js"; if (!("EventSource" in global)) { // @ts-expect-error - figure out how to use --experimental-eventsource with vitest global.EventSource = EventSource; } it("proxies messages between SSE and stdio servers", async () => { const stdioTransport = new StdioClientTransport({ args: ["src/simple-stdio-server.ts"], command: "tsx", }); const stdioClient = new Client( { name: "mcp-proxy", version: "1.0.0", }, { capabilities: {}, }, ); await stdioClient.connect(stdioTransport); const serverVersion = stdioClient.getServerVersion() as { name: string; version: string; }; const serverCapabilities = stdioClient.getServerCapabilities() as { capabilities: Record<string, unknown>; }; const port = await getRandomPort(); const onConnect = vi.fn(); const onClose = vi.fn(); await startSSEServer({ createServer: async () => { const mcpServer = new Server(serverVersion, { capabilities: serverCapabilities, }); await proxyServer({ client: stdioClient, server: mcpServer, serverCapabilities, }); return mcpServer; }, endpoint: "/sse", onClose, onConnect, port, }); const sseClient = new Client( { name: "sse-client", version: "1.0.0", }, { capabilities: {}, }, ); const transport = new SSEClientTransport( new URL(`http://localhost:${port}/sse`), ); await sseClient.connect(transport); const result = await sseClient.listResources(); expect(result).toEqual({ resources: [ { name: "Example Resource", uri: "file:///example.txt", }, ], }); expect( await sseClient.readResource({ uri: result.resources[0].uri }, {}), ).toEqual({ contents: [ { mimeType: "text/plain", text: "This is the content of the example resource.", uri: "file:///example.txt", }, ], }); expect(await sseClient.subscribeResource({ uri: "xyz" })).toEqual({}); expect(await sseClient.unsubscribeResource({ uri: "xyz" })).toEqual({}); expect(await sseClient.listResourceTemplates()).toEqual({ resourceTemplates: [ { description: "Specify the filename to retrieve", name: "Example resource template", uriTemplate: `file://{filename}`, }, ], }); expect(onConnect).toHaveBeenCalled(); expect(onClose).not.toHaveBeenCalled(); await sseClient.close(); await delay(100); expect(onClose).toHaveBeenCalled(); });