public function test_active()
{
$default = factory(Task::class)->create(['completed' => null]);
$active = factory(Task::class)->create(['completed' => false]);
$inactive = factory(Task::class)->create(['completed' => true]);
$tasks = Task::active()->lists('id');
$this->assertContains($default->id, $tasks);
$this->assertContains($active->id, $tasks);
$this->assertNotContains($inactive->id, $tasks);
}