Merge pull request #1782 from Simon-Will/1781-make-tests-work-with-phpunit-8

Make tests work with phpunit 8

diff --combined docs/admin/Installation.md
index 765b2716f275e8f8a3eeb062d44ca05d6d4ef78b,691a22b3f1a084b54acc9ec6ed719eb6aa1c733d..25b4f14ce1d8ea9f288e2dc5d42752822262c568
--- 1/docs/admin/Installation.md
--- 2/docs/admin/Installation.md
+++ b/docs/admin/Installation.md
@@@ -4,7 -4,6 +4,7 @@@ This page contains generic installatio
  prerequisites. There are also step-by-step instructions available for
  the following operating systems:
  
 +  * [Ubuntu 20.04](../appendix/Install-on-Ubuntu-20.md)
    * [Ubuntu 18.04](../appendix/Install-on-Ubuntu-18.md)
    * [Ubuntu 16.04](../appendix/Install-on-Ubuntu-16.md)
    * [CentOS 7.2](../appendix/Install-on-Centos-7.md)
@@@ -57,7 -56,7 +57,7 @@@ For running tests
  
    * [behave](http://pythonhosted.org/behave/)
    * [nose](https://nose.readthedocs.io)
-   * [phpunit](https://phpunit.de)
+   * [phpunit](https://phpunit.de) >= 7.3
  
  ### Hardware