constrequest=require("supertest-light");constexpress=require("express");constassert=require("assert");constapp=express();app.post("/user/:userId/messages",express.json(),(req,res,next)=>{returnres.end(`doubled: ${req.body.num*2}`);});request(app).post("/user/a1234/messages?language=en",{num: 34}).then(res=>{assert.equal(res.text,"doubled: 68","postData received and text is property assigned to response");});