Mocking an API for unit testing in Zend Framework 2

gistfile1.php

<?php

// Mock JSON
$json = <<< JSON
{
  "timestamp": 1385150462,
  "stuff": {
    "this": 2,
    "that": 4,
    "other": 1
    }
}
JSON

// Mock the client so it always returns the JSON we want    
$mockResponse = $this->getMock('\Zend\Http\Response');
$mockResponse->expects($this->any())
    ->method('getContent')
    ->will($this->returnValue($json));

// Mock the client so that it always returns the pre-prepared response
$mockClient = $this->getMock('\Zend\Http\Client');
$mockClient->expects($this->any())
    ->method('send')
    ->will($this->returnValue($mockResponse));

$object->setClient($mockClient);

/*
 * Inside your concrete object
 */

// The client injected into your object would be the mock client created in the test
$client = $mockClient;

// The response will be the mock response created in the test
$client->setUri('http://wherever.com');
$response = $mockClient->send();