/**
  * Test for getNamespaces().
  */
 public function testGetNamespaces()
 {
     $data = [['namespace_1', 'key_11'], ['namespace_2', 'key_21']];
     $holder = new KeyBag();
     $namespaces = [];
     foreach ($data as $row) {
         list($namespace, $key) = $row;
         $namespaces[] = $namespace;
         $holder->add($namespace, $key);
     }
     $this->assertEquals($namespaces, $holder->getNamespaces());
 }