public function testGetAt()
 {
     $entity1 = $this->getMock('InoPerunApi\\Entity\\EntityInterface');
     $entity2 = $this->getMock('InoPerunApi\\Entity\\EntityInterface');
     $collection = new Collection(array($entity1, $entity2));
     $this->assertSame($entity1, $collection->getAt(0));
     $this->assertSame($entity2, $collection->getAt(1));
     $this->assertNull($collection->getAt(2));
 }