Skip to main content

Matchers

The expect-mcp library provides custom Vitest matchers specifically designed for testing Model Context Protocol (MCP) integrations.

toHaveTool(toolName: string)​

Checks that an MCP server provides a tool with the specified name. This matcher works with MCPStdinSubprocess instances.

const app = mcpShell('node path/to/mcp-server.js');
await app.initialize();
await expect(app).toHaveTool('filesystem_list');

Parameters​

  • toolName: The name of the tool to check for

Example​

import { mcpShell } from 'expect-mcp';

test('server provides file operations', async () => {
  const app = mcpShell('node file-server.js');
  await app.initialize();

  await expect(app).toHaveTool('read_file');
  await expect(app).toHaveTool('write_file');

  app.close();
});

toHaveResource(resourceName: string)​

Checks that an MCP server provides a resource with the specified name. This matcher works with MCPStdinSubprocess instances.

const app = mcpShell('node path/to/mcp-server.js');
await app.initialize();
await expect(app).toHaveResource('config.json');

Parameters​

  • resourceName: The name of the resource to check for

Example​

import { mcpShell } from 'expect-mcp';

test('server provides configuration resources', async () => {
  const app = mcpShell('node config-server.js');
  await app.initialize();

  await expect(app).toHaveResource('app_config');
  await expect(app).toHaveResource('user_settings');

  app.close();
});