Devise\Support\IO\FileDiff::missing PHP Method

    public function missing($target, $source)
    {
        $missing = [];
        $targetSums = $this->md5($target);
        $sourceSums = $this->md5($source);
        foreach ($targetSums as $targetFile => $targetSum) {
            if (!array_key_exists($targetFile, $sourceSums) || $targetSums[$targetFile] == $sourceSums[$targetFile]) {
                $missing[] = $targetFile;
            }
        }
        return $missing;
    }

 public function test_it_finds_missing_files()
 {
     $FileDiff = new FileDiff();
     $missing = $FileDiff->missing(vfsStream::url('basedir/config1'), vfsStream::url('basedir/config2'));
     assertEquals(['database.php'], $missing);
 }