Symfony\Component\Process\Process::getEnv PHP Method

    public function getEnv()
    {
        return $this->env;
    }

 /**
  * Runs behat command with provided parameters
  *
  * @When /^I run "behat(?: ((?:\"|[^"])*))?"$/
  *
  * @param   string $argumentsString
  */
 public function iRunBehat($argumentsString = '')
 {
     $argumentsString = strtr($argumentsString, array('\'' => '"'));
     $this->process->setWorkingDirectory($this->workingDir);
     $this->process->setCommandLine(sprintf('%s %s %s %s', $this->phpBin, escapeshellarg(BEHAT_BIN_PATH), $argumentsString, strtr('--format-settings=\'{"timer": false}\'', array('\'' => '"', '"' => '\\"'))));
     // Don't reset the LANG variable on HHVM, because it breaks HHVM itself
     if (!defined('HHVM_VERSION')) {
         $env = $this->process->getEnv();
         $env['LANG'] = 'en';
         // Ensures that the default language is en, whatever the OS locale is.
         $this->process->setEnv($env);
     }
     $this->process->start();
     $this->process->wait();
 }