mcpTest(serverOrFactory, options?)

Connects a server and resolves with an McpHarness. Accepts an McpServer instance, a factory (sync or async) that returns one, or a spec for a server you cannot import - { command, args? } to spawn one over stdio, or { url, headers? } to reach one over HTTP. See testing an external server.

import { mcpTest } from "mcp-vitest";
import { createServer } from "./server.js";

const mcp = await mcpTest(() => createServer());

With autoClose: false you own the lifetime and call mcp.close() yourself. Outside a vitest test context, auto-close is skipped and closing is always yours.