ConfigTest::withEnv PHP Method

    public function withEnv($newEnv, $callback)
    {
        // reset environment variables
        $oldEnv = $this->resetEnv($newEnv + array('HOME' => null, 'PHPBREW_HOME' => getenv('PHPBREW_HOME'), 'PHPBREW_PATH' => null, 'PHPBREW_PHP' => null, 'PHPBREW_ROOT' => getenv('PHPBREW_ROOT'), 'PHPBREW_LOOKUP_PREFIX' => null));
        try {
            $callback($this);
            $this->resetEnv($oldEnv);
        } catch (\Exception $e) {
            $this->resetEnv($oldEnv);
            throw $e;
        }
    }