import { expect } from 'tstyche' import fastify from '../../fastify.js' type TestType = void declare module '../../fastify' { interface FastifyRequest { testProp: TestType; } interface FastifyReply { testProp: TestType; } } fastify().get('/', (req, res) => { expect(req.testProp).type.toBe() expect(res.testProp).type.toBe() })