https://medium.com/@wataruoguchi/a-javascript-users-first-aws-lambda-function-ed74c0441d6

2019_05_21_02.js

// __tests__/handler.spec.js
const handler = require('../handler.js');
const event = require('../tests/event.json');
test('correct keys get generated', () => {
  handler.handler(event, null, (error, success) => {
    expect(error).toBe(null);
    expect(success.key).toBe('my video.mp4');
    expect(success.sourceKey).toBe('my video.mp4');
    expect(success.outputKey).toBe('my video');
  })
})