PhpCsFixer\Fixer\Operator\ConcatSpaceFixer::configure PHP Method

    public function configure(array $configuration = null)
    {
        if (null === $configuration) {
            $this->fixCallback = 'fixConcatenationToNoSpace';
            return;
        }
        if (!array_key_exists('spacing', $configuration)) {
            throw new InvalidFixerConfigurationException($this->getName(), 'Missing "spacing" configuration.');
        }
        switch ($configuration['spacing']) {
            case 'one':
                $this->fixCallback = 'fixConcatenationToSingleSpace';
                break;
            case 'none':
                $this->fixCallback = 'fixConcatenationToNoSpace';
                break;
            default:
                throw new InvalidFixerConfigurationException($this->getName(), '"spacing" configuration must be "one" or "none".');
        }
    }