How to use the intern.default.registerPlugin function in intern

const intern = require("intern").default;
const http = require("http");

var url = function(path, params) {
  var base = intern.config.siteRoot + path;
  return params ? base + params : base;
};

/*
This method makes a call to our API and
checks that the server is returning fixture data,
it will also check if there's anything wrong with the server.
*/

intern.registerPlugin("checkServer", function() {
  return new Promise(function(resolve, reject) {
    var request = http.get(url("/api/issues/100"), function(response) {
      response.on("data", function(data) {
        try {
          var json = JSON.parse(data);
          if (!json.hasOwnProperty("_fixture")) {
            console.log("Intern checkServer has failed: (json)\n\n", json);
            reject(
              new Error(
                `
            =======================================================
            It seems like you didn't start the server in test mode.
            Open another terminal and window type:
           \x1b[32m npm run start:test\x1b[0m
            or
           \x1b[32m python run.py -t\x1b[0m