So you had an Alexa device and you wanna make you own skill, here we will learn how we can make our custom skill and test it locally without depending Aws Lambda

First step install the ASK-CLI

npm install -g ask-cli

We will generate our skill starter with

ask new

Choose NodeJs, and self-hosted

Next step we will add Virtual-Alexa dependencies

npm install virtual-alexa --save-dev

Enter into the created folder and add a new node project with

npm init

Add this necessary dependencies

npm i ask-sdk-core ask-sdk-model
npm i virtual-alexa --save-dev

In your package.json file add this start script

 "scripts": {
    "start": "node index.js"
  }

And for the last step create a new file called index.js and we will :

• Init an instance of Virtual alexa
• Handle our lamdba function to it and add our options like locales, interaction models, ...
• Start an intents
• Print the result (alexa speech)

const va = require("virtual-alexa");
const _defaultHandler = va.VirtualAlexa.Builder()
  .handler("./lambda/index.js") // Lambda file
  .interactionModelFile("./skill-package/interactionModels/custom/en-US.json") // Interaction file
  .locale("en-US")
  .create();


_defaultHandler.intend("HelloWorldIntent").then((payload) => {
// Print speech to console
  console.log("OutputSpeech: " + payload.response.outputSpeech.ssml);
});

Run with

npm run start

If everything is ok you should be able to read the alexa's output speech in your console

And that it, now you can develop your skill and test the output without send your code.

So if we recap, we used the 'hello-world' starter generated by ASK-CLI, we added a node application next to it using the 'virtual-alexa' dependency

As long as we are there we can take the opportunity to add tests, no?

I promise it will take a minute.

We begin with dev dependencies, so wo can add mocha, chai and nyc

npm i mocha chai nyc --save-dev

Create a test folder, and a new "index-test.js" file, in your package.json add this test script :

"test": "nyc mocha test/*-test.js"

So now we can add the usual structure of a test file into 'index-test.js'.

const expect = require("chai").expect;
const VirtualAlexa = require("virtual-alexa").VirtualAlexa;

describe("Test hello world intent", async function() {
  const alexa = VirtualAlexa.Builder()
    .handler("./lambda/index.js") // Lambda function file and name
    .interactionModelFile("./skill-package/interactionModels/custom/en-US.json") // Path to interaction model file
    .create();

  it("Should be Hello World!", async function() {
    const helloWorldResponse = await alexa.intend("HelloWorldIntent");
    expect(helloWorldResponse.response.outputSpeech.ssml).to.include(
      "Hello World!"
    );
  });
});

run with

npm run test

If everything is ok you should be able to see our test result

And that's it ! Now you can write your skill logic, run and test it.

You can also take a look to Ask Toolkit for vscode

See also : Secure the endpoint of my Skills Alexa application (futur post?)