src/Environment/Detector.php
public function setEnvironment($environment)
    {
        $environment = strtolower($environment);

        // list of implemented environments
        if (in_array($environment, $this->implemented)) {
            $this->environment = $environment;
            return $this;
        }

        // Linux, Unix and OSX don't differ much, therefore
        // we can use the same implementation
        if (preg_match('/(Linux|Unix|Darwin)/i', $environment, $match)) {
            $this->environment = 'unix';
            return $this;
        }

        // if the OS name begins with Win then
        // it's most likely Windows
        if ('WIN' === strtoupper(substr($environment, 0, 3))) {
            throw new \UnexpectedValueException("Windows isn't supported.");
        }

        // fallback to Unix
        $this->environment = 'unix';

        return $this;
    }
public function setEnvironment($environment)
    {
        $environment = strtolower($environment);

        // list of implemented environments
        if (in_array($environment, $this->implemented)) {
            $this->environment = $environment;
            return $this;
        }

        // Linux, Unix and OSX don't differ much, therefore
        // we can use the same implementation
        if (preg_match('/(Linux|Unix|Darwin)/i', $environment, $match)) {
            $this->environment = 'unix';
            return $this;
        }

        // if the OS name begins with Win then
        // it's most likely Windows
        if ('WIN' === strtoupper(substr($environment, 0, 3))) {
            throw new \UnexpectedValueException("Windows isn't supported.");
        }

        // fallback to Unix
        $this->environment = 'unix';

        return $this;
    }
Sets the environment

Falls back to Unix if the environment is not implemented

@param $environment
@return $this

@throws \UnexpectedValueException