title: Testing an array in laravel phpunit
body: <p>I have an array output in laravel, the structure looks like follows:</p>
  
  <pre><code>array:1 [
    0 =&gt; {#35
      +"id": 152
      +"user_id": 123
      +"post_id": 456
      +"content": "impedit"
      +"created_at": "04-09-2016 01:24"
      +"updated_at": "2016-09-04 01:24:51"
    }
  ]
  </code></pre>
  
  <p>How to test the array structure contains keys <code>id</code>、<code>user_id</code> ...？ </p>
  
  <p>I tried assertArrayHasKey('user_id', $array)，but it shows failed. 
  Thanks.</p>