public function showFile($file, $ref = 'HEAD')
    {
        /** @var $result CallResult */
        $result = $this->getGit()->{'show'}($this->getRepositoryPath(), array(
            sprintf('%s:%s', $ref, $file)
        ));
        $result->assertSuccess(sprintf('Cannot show "%s" at "%s" from "%s"',
            $file, $ref, $this->getRepositoryPath()
        ));


        return $result->getStdOut();
    }