/**
  * @param Provider $provider
  */
 public function addProvider(Provider $provider)
 {
     $this->providers->addProvider($provider);
 }
 public function testConfig()
 {
     $provider = new CollectionProvider([new ArrayProvider(['foo' => 'bar']), new ArrayProvider(['bar' => 'foo'])]);
     $this->assertEquals(['foo' => 'bar', 'bar' => 'foo'], $provider->getConfig());
 }