anchor.diff:  
   `mvn test`:: can be used to perform the the build and unit test.
   `mvn verify`:: can be used to perform the build and test including the end-to-end test with a real browser (see <<caution:chrome-does-not-work>>).
  -`mvn verify -Pheadless`:: Used to run with Firefox instead of Chrome (cf. <<Headless integration testing>>)
  +`mvn verify -Pheadless`:: Used to run with Firefox instead of Chrome (cf. <<sec:headless-integration-testing>>)
   `mvn clean`:: may be used as usual to clean up the local build.
   `mvn clean -Pveryclean`:: also cleans up the NPM and Node installation.
   
  +[[sec:testing-with-maven-docker]]
   ==== Testing with Maven (Docker)
   
   If you want to run the build as it is done on our CI-Server (Jenkins), please run `./docker-mvn.sh` with the deired Maven goals, e.g.,
  
positive.code: npm run e2e_headless
  ----
  
  ==== Testing with Maven (direct)
  
  The Maven build is based on the Maven Frontend Plugin.
  
negative.code: 
  Testing can be performed in the following modes
  
  Testing with NPM:: cf. <<sec:testing-with-npm>>.
  
  NOTE:
  Both of the following modes are based on this mode and effectively call `npm` but are used via Maven which enables a local installation of the desired NPM and Node versions first.
  It then uses these versions to perform the build and test of the application.
  On CI (https://dev.dukecon.org/jenkins/job/dukecon_pwa/[The DukeCon Jenkins]) the build and tests are performed via this mode.
  
  Build with Maven (directly):: cf. <<sec:testing-with-maven-direct>>
  
  Build with Maven (in Docker):: cf. <<sec:testing-with-maven-docker>>
  
  [[sec:testing-with-npm]]
  ==== Testing with NPM
  
  ===== Unit testing
  