public function testItMergesInNewConfig()
 {
     $config = new ApplicationConfig(['group' => ['keyA' => 'valueA', 'keyB' => 'valueX']]);
     $config->merge(['group' => ['keyB' => 'valueB']]);
     assertSame('valueA', $config['group.keyA']);
     assertSame('valueB', $config['group.keyB']);
 }
 /**
  * @param string $filename
  *
  * @return void
  */
 private function readFileAndMergeConfig($filename)
 {
     $reader = $this->getReaderFor($filename);
     $this->config->merge($reader->read($filename));
 }