convert the rest of the helper files to ts

test/utils/net-utils.js

@@ -1,26 +0,0 @@
-'use strict'; // eslint-disable-line 
-
-const net = require('net');
-
-// using a free port instead of a constant port enables parallelization
-function getFreePort() {
-  return new Promise((resolve, reject) => {
-    const server = net.createServer();
-    let port;
-    server.on('listening', function() {
-      port = server.address().port;
-      server.close();
-    });
-    server.on('close', function() {
-      resolve(port);
-    });
-    server.on('error', function(error) {
-      reject(error);
-    });
-    server.listen(0);
-  });
-}
-
-module.exports = {
-  getFreePort
-};