This pre-commit hook should be placed in the file $repo/.git/hooks/pre-commit

pre-commit

#!/usr/bin/env php
<?php
exec("phpunit --configuration .phpunit.xml", $output, $returnCode );

if ( $returnCode !== 0 ) {
  $summary = array_pop( $output );
  printf( "Stop `git commit`, test failed with: ( %s )\n", $summary );
  exit( 1 );
}
exit( 0 );