refactor into utility methods

Author: amaanbs

lib/fetchDownloadSourceUrl.js

@@ -1,12 +1,13 @@
 const https = require('https'),
   fs = require('fs'),
-  HttpsProxyAgent = require('https-proxy-agent');
+  HttpsProxyAgent = require('https-proxy-agent'),
+  { isUndefined } = require('./util');
 
 const authToken = process.argv[2], bsHost = process.argv[3], proxyHost = process.argv[6], proxyPort = process.argv[7], useCaCertificate = process.argv[8], downloadFallback = process.argv[4], downloadErrorMessage = process.argv[5];
 
 let body = '', data = {'auth_token': authToken};
 const options = {
-  hostname: bsHost && bsHost !== 'undefined' ? bsHost : 'local.browserstack.com',
+  hostname: !isUndefined(bsHost) ? bsHost : 'local.browserstack.com',
   port: 443,
   path: '/binary/api/v1/endpoint',
   method: 'POST',
@@ -20,13 +21,13 @@ if (downloadFallback == 'true') {
   data['error_message'] = downloadErrorMessage;
 }
 
-if(proxyHost && proxyPort && proxyHost !== 'undefined' && proxyPort !== 'undefined') {
+if(!isUndefined(proxyHost) && !isUndefined(proxyPort)) {
   options.agent = new HttpsProxyAgent({
     host: proxyHost,
     port: proxyPort
   });
 }
-if (useCaCertificate && useCaCertificate !== 'undefined') {
+if (!isUndefined(useCaCertificate)) {
   try {
     options.ca = fs.readFileSync(useCaCertificate);
   } catch(err) {

lib/util.js

@@ -0,0 +1 @@
+module.exports.isUndefined = value => (value === undefined || value === null || value === 'undefined');