TT-00 style: Add headless browser testing script

Author: josepato87

README.md

@@ -81,7 +81,9 @@ Run `ng build` to build the project. The build artifacts will be stored in the `
 
 ## Running unit tests
 
-Run `ng test` to execute the unit tests via [Karma](https://karma-runner.github.io).
+Run `npm run test` or `ng test` to execute the unit tests via [Karma](https://karma-runner.github.io).
+
+Run `npm run test-headless` or `ng test --browsers ChromeHeadless` to execute the unit tests via "Headless Browser".
 
 ## Running mutation tests
 Mutation tests have been enabled using stryker. You can run those tests locally, it takes ~4 hours to have the results. If you want to run them locally please install stryker locally:

package.json

@@ -7,6 +7,7 @@
     "start": "ng serve",
     "build": "ng build",
     "test": "ng test",
+    "test-headless": "ng test --browsers ChromeHeadless",
     "ci-test": "ng test --no-watch --no-progress --browsers ChromeHeadless",
     "lint": "ng lint",
     "e2e": "ng e2e"