Laravel 'phpunit --filter' returns 'phpunit --help'

I have installed Laravel6.0 with php7.2 on a MacBook Air 2018 using PHPUnit 8.3.5.

When I try to run phpunit --filter it returns like I wrote phpunit --help.

Can someone help me out?

phpunit --filter TestFunction

PHPUnit 8.3.5 by Sebastian Bergmann and contributors.

Usage:
  phpunit [options] UnitTest [UnitTest.php]
  phpunit [options] <directory>

Code Coverage Options:
  --coverage-clover <file>    Generate code coverage
                              report in Clover XML
                              format
  --coverage-crap4j <file>    Generate code coverage
                              report in Crap4J XML
                              format
  --coverage-html <dir>       Generate code coverage
                              report in HTML format
  --coverage-php <file>       Export PHP_CodeCoverage
                              object to file
  --coverage-text=<file>      Generate code coverage
                              report in text format
                              [default: standard
                              output]
...

UPDATE/FIX

I found out that I my terminal was in the wrong directory!