foo.js

const async = require('async')

function waitForUpdate (appId, updatedInitial) {
  var updated = updatedInitial
  return new Promise((resolve, reject) => {
    async.whilst(
      () => updated === updatedInitial,
      (callback) => {
        getLastUpdated(appId, (err, lastUpdated) => {
          if (err) {
            return callback(err)
          }
          updated = lastUpdated
          callback(null, updated)
        })
      },
      (err, result) => {
        if (err) {
          return reject(err)
        }
        resolve(result)
      }
    )
  })
}

function getLastUpdated (appId, callback) {
  this.getCloudHubCookie().then((cookie) => {
    let options = {
      headers: { Cookie: `${cookie.name}=${cookie.value}` },
      json: true
    }
    request.get(`${this.browser.baseUrl}/api/v1/apps/${appId}`, options, (err, res, body) => {
      if (err) {
        return callback(err)
      }
      callback(null, body.lastUpdated)
    })
  })
}