我有一个基本方法，它接受cookie并返回有效用户

const getInitialState = (id_token) => {
  let initialState;
  return new Promise((resolve,reject) => {
    if(id_token == null){
      initialState = {userDetails:{username: 'Anonymous',isAuthenticated: false}}
      resolve(initialState)
    }else{
        var decoded = jwt.verify(JSON.parse(id_token),'rush2112')
        db.one('SELECT  * FROM account WHERE account_id = $1',decoded.account_id)
          .then(function(result){
            initialState = {userDetails:{username:result.username,isAuthenticated:true}}
            resolve(initialState)
          })
          .catch(function(err){
            console.log('There was something wrong with the token')
            reject('There was an error parsing the token')
          })
    }
  })
}

既然这是个承诺-我就用我的承诺。
我可以成功地测试第一个条件（cookie是没有预设）与以下

it('should return anonymous user if id_token isnt preset',function(){
    let id_token = null
    return expect(getInitialState(id_token)).to.eventually.have.deep.property('userDetails.username','Anonymous')
  })

然而，我不能/不太确定如何测试第二部分，因为它同时依赖于jwt和外部db调用（它本身是另一个promise对象）
到目前为止，我已经尝试过了。stub db调用返回这个错误，我发现它非常模糊

1) GetInitialState should return a valid user if id_token is valid:
     TypeError: Cannot redefine property: connect
      at Function.defineProperty (native)
      at Object.wrapMethod (node_modules/sinon/lib/sinon/util/core.js:128:24)
      at stub (node_modules/sinon/lib/sinon/stub.js:67:26)
      at node_modules/sinon/lib/sinon/stub.js:60:25
      at node_modules/sinon/lib/sinon/walk.js:28:30
      at Array.forEach (native)
      at walkInternal (node_modules/sinon/lib/sinon/walk.js:23:45)
      at Object.walk (node_modules/sinon/lib/sinon/walk.js:49:20)
      at Object.stub (node_modules/sinon/lib/sinon/stub.js:52:23)
      at Context.<anonymous> (getInitialState.spec.js:27:11)

我猜它不允许我stub整个db对象。我还能怎么做呢？我只是希望jwt和db调用都不抛出任何错误。我只是测试如果cookie是有效的，是否会返回一个正确的对象

it('should return a valid user if id_token is valid',function(){
    sinon.stub(jwt,'verify').returns({username:foo});
    sinon.stub(db).resolves() // unsure of what to do here
    id_token = ' Foo----bar '
    return expect(getInitialState(id_token)).to.eventually.be.true
  })