PHPUnit Guzzle响应不起作用

I started using PHPUnit and Guzzle to test some API but when I run the following unit test, I don't receive back the right json. What is wrong in the code?

<?php

require('vendor/autoload.php');

class TestAll extends PHPUnit_Framework_TestCase
{
    protected $client;

    protected function setUp()
    {
        $this->client = new GuzzleHttp\Client([
            'base_uri' => 'https://url',
            'verify'  => false,
            'headers' => ['Accept' => 'application/json']

            ]);
    }

    public function testGet_ValidInput_TestAllObject()
    {
        $response = $this->client->get('/test_all');
        var_dump($response->getBody());
        $this->assertEquals(200, $response->getStatusCode());
        $data = json_decode($response->getBody(), true);

    }
}

Here is what I am getting:

    .                                                                   1 / 1 (100%)object(GuzzleHttp\Psr7\Stream)#39 (7) {
  ["stream":"GuzzleHttp\Psr7\Stream":private]=>
  resource(1127) of type (stream)
  ["size":"GuzzleHttp\Psr7\Stream":private]=>
  NULL
  ["seekable":"GuzzleHttp\Psr7\Stream":private]=>
  bool(true)
  ["readable":"GuzzleHttp\Psr7\Stream":private]=>
  bool(true)
  ["writable":"GuzzleHttp\Psr7\Stream":private]=>
  bool(true)
  ["uri":"GuzzleHttp\Psr7\Stream":private]=>
  string(10) "php://temp"
  ["customMetadata":"GuzzleHttp\Psr7\Stream":private]=>
  array(0) {
  }
}

From the docs:

The entity body object of a response can be retrieved by calling $response->getBody().

Also, looking at Guzzle code, it's clear it's returning an object which implements StreamInterface:

/**
 * Get the body of the message
 *
 * @return StreamInterface|null
 */
public function getBody();

What you need is to use json() method which parses and returns JSON response body (already decoded). Try the following:

public function testGet_ValidInput_TestAllObject()
{
    $response = $this->client->get('/test_all');
    $this->assertEquals(200, $response->getStatusCode());
    $data = $response->json();
    var_dump($data);
}