while learning to test api with jest, I encountered this function:
const checkHasLogin = async (ctx, next) => {
  if (ctx.session.userName) {
    ctx.body = {
      success: true,
      msg: ctx.session.userName
    }
  } else {
    ctx.body = {
      success: false,
      msg: ""
    }
  }
}
 where  ctx.session  is: 
// app.js
const session = require("koa-session")
const CONFIG = {
  key: "koa:todo",
  maxAge: 86400000,
  overwrite: true,
  httpOnly: true,
  signed: true,
  rolling: false,
  renew: false
}
app.use(session(CONFIG, app))
 I"d like to ask if there is any way to simulate this  ctx.session . 
// 
test("user login if session.userName is exist", async () => {
  const res = await request(app.callback())
    .get("/api/login/hasLogin")
  expect(res.body.success).toBe(true)
})
						