Stubmatic | Mock HTTP calls without coding. Designed specially | Mock library

I checked some NPM libraries to test a webpages or web-services. But all of them expect that the server is already running. Since I want to automate functional testing, how can I setup NPM package in such a way that

1. It can start the server
2. Test the application
3. Stop the server

So that I can test it locally, as well as on online CI tools like travis-ci or circleci.

Case 1: Webservice

I wrote a NPM package which starts nodejs HTTP(s) server. It can be started from command line $stubmatic. Currently, I use 2 approaches to test it,

1. manual : I manually start it from command line. Then run the tests.
2. Automatic: I use exec module to run a unix command which can start the application and run pkill command to kill the application. But for this automation, my application need to be installed on testing machine.

Case 2: Website

I have create a NPM package: fast-xml-parser and created a demo page within the repo so that I can be tested in the browser. To test the demo page, I currently start a local server using http-server npm package manually. Test the application.

What can be the better way to write automate functional tests for node js applications?

Note:

• I never used task runners like gulp or grunt. So I'm not sure if they can help in this case.
• In case 1, my application starts node js native HTTP server. I'm not using any 3rd party application like express currently.