public function testOnlyReturnsCollectionWithGivenModelKeys()
{
$e1 = new Entity();
$e1->id = 1;
$e2 = new Entity();
$e2->id = 2;
$e3 = new Entity();
$e3->id = 3;
$c = new Collection([$e1, $e2, $e3]);
$this->assertEquals(new Collection([$e1]), $c->only(1));
$this->assertEquals(new Collection([$e2, $e3]), $c->only([2, 3]));
}
