test_2_dry_refactor.php

<?php

class DoesAwesomeStuff {
    protected $meta = [];
    protected $metaExtractor;

    public function __construct($metaExtractor)
    {
        $this->metaExtractor = $metaExtractor;
    }

    public function doesAwesomeness()
    {
        // does awesome stuff
    }

    public function getMeta($key)
    {
        return $this->metaExtractor->fetch($this->meta, $key);
    }

    public function setMeta($meta)
    {
        if (! isset($meta['key'], $meta['value'])) {
            throw new Exception('Bad meta data');
        }

        $meta['created_by'] = auth()->id();
        $this->meta = $meta;
    }
}

class DoesCoolStuff {
    protected $meta = [];
    protected $metaExtractor;

    public function __construct($metaExtractor)
    {
        $this->metaExtractor = $metaExtractor;
    }

    public function doesCoolStuff()
    {
        // does cool stuff
    }

    public function getMeta($key)
    {
        return $this->metaExtractor->fetch($this->meta, $key);
    }

    public function setMeta($meta)
    {
        if (! isset($meta['key'], $meta['value'])) {
            throw new Exception('Bad meta data');
        }

        $this->meta = $meta;
    }
}