MySQL MCP Server

import { handleQuery, handleExecute, handleListTables, handleDescribeTable, handleShowStatement, handleExplain, QueryArgs, ExecuteArgs, DescribeTableArgs, ShowArgs, ExplainArgs } from '../src/handlers.js'; import { Pool } from 'mysql2/promise'; jest.mock('mysql2/promise'); const mockPool = { query: jest.fn() } as unknown as Pool; describe('handlers', () => { beforeEach(() => { jest.clearAllMocks(); }); describe('handleQuery', () => { it('should return rows for valid SELECT', async () => { mockPool.query = jest.fn().mockResolvedValue([[{ id: 1, name: 'test' }]]); const args: QueryArgs = { sql: 'SELECT * FROM users' }; const result = await handleQuery(mockPool, args); expect(result.content[0].text).toContain('test'); }); it('should throw error for non-SELECT', async () => { const args: QueryArgs = { sql: 'UPDATE users SET name="a"' }; await expect(handleQuery(mockPool, args)).rejects.toThrow(); }); }); describe('handleExecute', () => { it('should return result for valid non-SELECT', async () => { mockPool.query = jest.fn().mockResolvedValue([{ affectedRows: 1 }]); const args: ExecuteArgs = { sql: 'UPDATE users SET name="a"' }; const result = await handleExecute(mockPool, args); expect(result.content[0].text).toContain('affectedRows'); }); it('should throw error for SELECT', async () => { const args: ExecuteArgs = { sql: 'SELECT * FROM users' }; await expect(handleExecute(mockPool, args)).rejects.toThrow(); }); }); describe('handleListTables', () => { it('should return tables', async () => { mockPool.query = jest.fn().mockResolvedValue([[{ 'Tables_in_test': 'users' }]]); const result = await handleListTables(mockPool); expect(result.content[0].text).toContain('users'); }); }); describe('handleDescribeTable', () => { it('should return table structure', async () => { mockPool.query = jest.fn().mockResolvedValue([[{ Field: 'id', Type: 'int' }]]); const args: DescribeTableArgs = { table: 'users' }; const result = await handleDescribeTable(mockPool, args); expect(result.content[0].text).toContain('Field'); }); it('should throw error if table is missing', async () => { // @ts-expect-error await expect(handleDescribeTable(mockPool, {})).rejects.toThrow(); }); }); }); describe('handleShowStatement', () => { it('should return result for valid SHOW statement', async () => { mockPool.query = jest.fn().mockResolvedValue([[{ Variable_name: 'max_connections', Value: '151' }]]); const args: ShowArgs = { sql: 'SHOW VARIABLES' }; const result = await handleShowStatement(mockPool, args); expect(result.content[0].text).toContain('max_connections'); }); it('should throw error for non-SHOW statement', async () => { const args: ShowArgs = { sql: 'SELECT * FROM users' }; await expect(handleShowStatement(mockPool, args)).rejects.toThrow(); }); }); describe('handleExplain', () => { it('should return execution plan for valid SQL', async () => { mockPool.query = jest.fn().mockResolvedValue([[ { id: 1, select_type: 'SIMPLE', table: 'users', type: 'ALL', rows: 100 } ]]); const args: ExplainArgs = { sql: 'SELECT * FROM users WHERE id = 1' }; const result = await handleExplain(mockPool, args); expect(mockPool.query).toHaveBeenCalledWith('EXPLAIN SELECT * FROM users WHERE id = 1'); expect(result.content[0].text).toContain('SIMPLE'); expect(result.content[0].text).toContain('users'); }); it('should throw error when SQL is missing', async () => { const args: ExplainArgs = { sql: '' }; await expect(handleExplain(mockPool, args)).rejects.toThrow('SQL query is required for EXPLAIN'); }); });