alexa.js

const Alexa = require('alexa-sdk');

// Define skill name
const SKILL_NAME = "Test Example";

// Define translation settings
const languageStrings = {
    'en': {
        'translation': {
            'WELCOME' : "Welcome to Gloucester Guide!"
        }
    },
    'de-DE': {
      'translation': {
        'WELCOME' : "Willkommen in Gloucester Guide!",
      }
    }
};

// Regist intent handlers
const handlers = {
    'LaunchRequest': function () {
        var say = this.t('WELCOME');
        this.emit(':tellWithCard', say, 'Welcome', say)
    },
};


exports.handler = function(event, context, callback) {
    var alexa = Alexa.handler(event, context);
    alexa.resources = languageStrings;
    alexa.registerHandlers(handlers);
    alexa.execute();
};

alexa.test.js

const assert = require('assert')
const event = require('./events/base')
const func = require('../src/index.js')

event.request = {
  "type": "LaunchRequest",
  "requestId": "request5678",
  "locale": "en-US"
}
const { handler } = func
const callback = () => console.log()

describe('Test Alexa function', () => {
    it('should be succeed', () => {
        handler(event, {
            succeed: (data) => {
                assert.ok(true)
            },
            fail: (err) => {
                assert.ok(false)
            }
        }, callback)
    })
    it('should be say english content', () => {
      event.request.locale = "en-US"
      handler(event, {
        succeed: (data) => {
          assert.ok(true)
          const { response } = data
          const {
            card,
            outputSpeech
          } = response
          assert.deepEqual(
            outputSpeech,
            {
              type: 'SSML',
              ssml: "<speak> Welcome to Gloucester Guide! </speak>"
            }
          )
          assert.deepEqual(
            card,
            {
              type: 'Simple',
              title: "Welcome",
              content: "Welcome to Gloucester Guide!"
            }
          )
        },
        fail: (err) => {
          assert.ok(false)
        }
    }, callback)
    })
    it('should be say german content', () => {
      event.request.locale = "de-DE"
        handler(event, {
            succeed: (data) => {
                assert.ok(true)
                const { response } = data
                const {
                  card,
                  outputSpeech
                } = response
                assert.deepEqual(
                  outputSpeech,
                  {
                    type: 'SSML',
                    ssml: "<speak> Willkommen in Gloucester Guide! </speak>"
                  }
                )
                assert.deepEqual(
                  card,
                  {
                    type: 'Simple',
                    title: "Welcome",
                    content: "Willkommen in Gloucester Guide!"
                  }
                )
            },
            fail: (err) => {
                assert.ok(false)
            }
        }, callback)
    })
})