public function validatePhpVersionTravisYml($travisYml)
    {
        if (!isset($travisYml['php'])) {
            $this->output->writeln(
                '<info>No PHP version mentioned in .travis.yml!</info>'
            );

            return true;
        }

        if (!is_array($travisYml['php'])) {
            $this->output->writeln(
                '<error>PHP version mentioned in .travis.yml must be an array!</error>'
            );

            return false;
        }

        $versionParser = new VersionParser();
        foreach ($travisYml['php'] as $version) {
            try {
                if ('nightly' === $version) {
                    continue;
                }
                $versionParser->parseConstraints($version);
            } catch (\Exception $e) {
                $this->output->writeln('<error>' . $e->getMessage() . '</error>');

                return false;
            }
        }

        return true;
    }