laravel unit test seeJson is fail with child level structure

Question

I used phpunit to test the Laravel API. The API has return result like

{
    success: true,
    data: {
        'attr1': 'value1',
        'attr2': 'value2'
    }
}

when I used:

 seeJson([
    'success' => true
 ])

it's pass, but when I used

seeJson([
    'success' => true,
    'data' => [
        'attr1' => 'value1'
    ]
])

it's fail. any way to make it pass?

Please help me. thank you.