Testing a Promise that returns a Promise

I have a function that looks like

const BypassSFTP = {
  execute: function(config, callback) {
    const sftp = new Client()
    sftp.connect(config)
      .then(() => {
        return sftp.list('./');
      })
      .then((fileList) => {
        console.log(fileList)
        return retrieveFileStreams.go(sftp, fileList, "sftp")
      })
      .then((fileStreams) => {
        console.log(fileStreams)
        return streamToString(fileStreams)
      })
})}

im stubbing it with sinon like

sinon.stub(Client.prototype, 'connect').callsFake(function(config) {
      return Q.when()
    });

    sinon.stub(Client.prototype, 'list').callsFake(function() {
      return Q.when('meow2')
    });

    sinon.stub(retrieveFileStreams, 'go').callsFake(function(a, b, c) {
      return Q.when('meow3')
    });

im doing some asserts like

bypassSFTP.execute(config, callback_2);
sinon.assert.calledOnce(Client.prototype.connect);
sinon.assert.calledOnce(Client.prototype.list);
sinon.assert.calledOnce(retrieveFileStreams.go);

Now the issue is that after the Client.connect call it does not recognize that the other function like sftp.list() are called

What would be the best way to test this?

via Seal