When I write my code I like to have my unit tests run automatically but sometimes I need to focus on a single test but I don't want to tab to the window where you're running your unit tests to run them (I know, how lazy can you be). When this happen I like to do two things.

The first is that I can run phpunit in a continuous loop with a one second delay so I can read the screen:

while(true); do vendor/bin/phpunit -c tests --filter <filter>; sleep 1; done

This works well but you end up having the tests run constantly which can drain your battery (if like me you aren't plugged in every so often). In this case I use the following:

while(true); do vendor/bin/phpunit -c tests --filter <filter>; read -p "Press Enter..."; done

Which will wait for an enter key before running the tests a second time.