Use headless chrome instead of phantomjs for tests

karma.conf.js

@@ -116,11 +116,25 @@ module.exports = function (config) {
         browsers: [
             'Chrome',
             //'PhantomJS',
+            //'ChromeHeadless',
         ],
 
+        customLaunchers: {
+            'ChromeHeadless': {
+                base: 'Chrome',
+                flags: [
+                    // See https://chromium.googlesource.com/chromium/src/+/lkgr/headless/README.md
+                    '--headless',
+                    '--disable-gpu',
+                    // Without a remote debugging port, Google Chrome exits immediately.
+                    '--remote-debugging-port=9222',
+                ],
+            }
+        },
+
         // Continuous Integration mode
         // if true, Karma captures browsers, runs the tests and exits
-        singleRun: true,
+        // singleRun: false,
 
         // Concurrency level
         // how many browser should be started simultaneous