public function testFilter() { $itemBefore = [['id' => 1, 'name' => 'Udonthani'], ['id' => 2, 'name' => 'Bangkok']]; $itemAfter = [['id' => 2, 'name' => 'Bangkok']]; $collection = new Collection($itemBefore); $result = $collection->filter(function ($item) { return $item['id'] == 2; }); $this->assertInstanceOf(Collection::class, $result); $this->assertEquals($itemAfter, $result->toArray()); }