private function fillRunQueue()
    {
        $opts = $this->options;
        while (\count($this->pending) && \count($this->running) < $opts->processes) {
            $tokenData = $this->getNextAvailableToken();
            if ($tokenData !== false) {
                $this->acquireToken($tokenData['token']);
                $env = ['TEST_TOKEN' => $tokenData['token'], 'UNIQUE_TEST_TOKEN' => $tokenData['unique']] + Habitat::getAll();
                $this->running[$tokenData['token']] = array_shift($this->pending)->run($opts->phpunit, $opts->filtered, $env, $opts->passthru, $opts->passthruPhp);
                if ($opts->verbose) {
                    $cmd = $this->running[$tokenData['token']];
                    echo "\nExecuting test via: {$cmd->getLastCommand()}\n";
                }
            }
        }
    }