Test Node.js API with Jest (and mockgoose)

Two questions here: 1) Is Jest a good options to test Node.js (express) APIs? 2) I'm trying to use Jest with Mockgoose, but I can't figure out how to establish the connection and run tests after. Here is my final attempt before coming on SO:

const Mongoose = require('mongoose').Mongoose
const mongoose = new Mongoose()
mongoose.Promise = require('bluebird')
const mockgoose = require('mockgoose')

const connectDB = (cb) => () => {
  return mockgoose(mongoose).then(() => {
    return mongoose.connect('mongodb://test/testingDB', err => {
      if (err) {
        console.log('err is', err)
        return process.exit()
      }
      return cb(() => {
        console.log('END') // this is logged
        mongoose.connection.close()
      })
    })
  })
}

describe('test api', connectDB((end) => {
  test('adds 1 + 2 to equal 3', () => {
    expect(1 + 2).toBe(3)
  })
  end()
}))

The error is Your test suite must contain at least one test. This error makes a bit of sense to me but I can't figure out how to solve it. Any suggestions?

Output:

Test suite failed to run

Your test suite must contain at least one test.