5 minute read
Introduction
When we write a client to integrate an API in our systems it is important to test it to be sure we can handle every possible response. Guzzle client provides a very simple way to mock external APIs responses: Guzzle Mock Handler. This tool provides a mock handler that can be used to fulfill HTTP requests with a response or exception by shifting return values off of a queue.
How does it work? Here’s an example provided by Guzzle documentation (https://docs.guzzlephp.org/en/stable/).
<?php
use GuzzleHttp\Client;
use GuzzleHttp\Handler\MockHandler;
use GuzzleHttp\HandlerStack;
use GuzzleHttp\Psr7\Response;
use GuzzleHttp\Psr7\Request;
use GuzzleHttp\Exception\RequestException;
// Create a mock and queue two responses.
$mock = new MockHandler([
new Response(200, ['X-Foo' => 'Bar']),
new Response(202, ['Content-Length' => 0]),
new RequestException("Error Communicating with Server", new Request('GET', 'test'))
]);
$handler = HandlerStack::create($mock);
$client = new Client(['handler' => $handler]);
// The first request is intercepted with the first response.
echo $client->request('GET', '/')->getStatusCode();
//> 200
// The second request is intercepted with the second response.
echo $client->request('GET', '/')->getStatusCode();
//> 202
A real use case
But how can we test our effective Symfony controller that has to handle all the responses? Let’s suppose we have a controller that returns a JsonResponse with a different message and status code based on what it gets from the APIs
<?php
use Symfony\Component\HttpFoundation\JsonResponse;
use MyNamespace\MyApiClient;
public function apiControllerAction(MyApiClient $client)
{
$response = $client->getFoo();
if($response->getStatusCode()===200){
return new JsonResponse(
[
'status'=>'ok',
'message' => $response->getBody()
],
200
);
}
if($response->getStatusCode()===404){
return new JsonResponse(
[
'status' => 'error',
'message' => 'foo not found'
],
404
);
}
return new JsonResponse(
[
'status'=>'error',
'message' => 'something went wrong'
],
500
);
}
MyApiClient has a constructor that initialize the HTTP client and a method who retrieves “foo” from the API.
<?php
namespace MyNamespace;
use Psr\Http\Client\ClientInterface;
class MyApiClient
{
public function __construct(ClientInterface $client)
{
$this->client = $client;
}
public function getFoo()
{
return $this->get('https://api-url/foo');
}
}
Symfony will automatically inject MyApiClient in our controller, but to make sure it will inject ClientInterface in MyApiClient we have to modify services.yaml to look like this:
Psr\Http\Client\ClientInterface: '@psr18.client'
psr18.client:
class: GuzzleHttp\Client
This way we are telling Symfony to inject Guzzle HTTP Client in MyApiClient.
Road to testing
Now we have to create the functional test for our controller. The test will expect 3 different responses according to API responses.
But before creating our test however, a preliminary step is needed. We have to create a class that extends Guzzle in order to easily manage the mock responses.
It will look like this:
<?php
namespace Tests\Fake;
use GuzzleHttp\Handler\MockHandler;
use GuzzleHttp\HandlerStack;
use GuzzleHttp\Client;
/**
* Class ClientFake
*/
class ClientFake extends Client
{
/** @var MockHandler */
protected $mockHandler;
/**
* ClientFake constructor.
*/
public function __construct()
{
$this->mockHandler = new MockHandler();
$handler = HandlerStack::create($this->mockHandler);
parent::__construct(['handler' => $handler]);
}
/**
* @param $responses
*/
public function appendResponse($responses): void
{
$this->mockHandler->append(...$responses);
}
}
This is not enough yet. We have to tell Symfony to use our ClientFake instead of
GuzzleHttp\Client when we are running our test. So we open our services_test.yml and we add following lines:
psr18.client:
public: true
class: Tests\Fake\ClientFake
When we are running our tests, Symfony will inject ClientFake in MyApiClient instead of real GuzzleClient. Are we ready to write our test now? Almost! We have to write a test case to initialize all the stuff we need.
<?php
namespace Test;
use Symfony\Bundle\FrameworkBundle\Client;
use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
class MockHandlerTestCase extends WebTestCase
{
/**
* @var Tests\Fake\ClientFake
*/
protected $clientInterface;
/** @var Client */
protected $client;
/** @var \Symfony\Component\DependencyInjection\ContainerInterface|null */
protected $Container;
public function __construct(?string $name = null, array $data = [], string $dataName = '')
{
parent::__construct($name, $data, $dataName);
$this->client = static::createClient();
$this->Container = $this->client->getContainer();
$this->clientInterface = $this->Container->get('psr18.client');
}
protected function prepareMock($response)
{
$this->clientInterface->appendResponse([$response]);
}
}
Tests
And now we can finally write our tests.
##Test 1 In the first one we simulate that APIs returns us a 200 code with a simple body.
<?php
use Tests\MockHandlerTestCase;
use GuzzleHttp\Psr7\Response as ClientResponse;
use Symfony\Component\HttpFoundation\Response;
class apiControllerTest extends MockHandlerTestCase
{
public function __construct($name = null, array $data = [], $dataName = '')
{
parent::__construct($name, $data, $dataName);
}
public function testOK(): void
{
//we set up our API mock response
$response200 = new ClientResponse(Response::HTTP_OK, [], json_encode(['foo'=>'bar']));
$this->prepareMock($response200);
//we navigate to our route
$this->client->request('GET', '/routeToApiController');
//we expect a 200 (from controller - not from api)
$this->assertEquals(200, $this->client->getResponse()->getStatusCode());
//we put controller's response in a variable
$result = \json_decode($this->client->getResponse()->getContent(), true);
//we check that controller give us what we expect
$this->assertEquals('ok', $result['status']);
}
}
Test 2
It will test a 404 response.
<?php
public function testNotFound(): void
{
//we set up our API mock response
$response404 = new ClientResponse(Response::HTTP_NOT_FOUND);
$this->prepareMock($response404);
//we navigate to our route
$this->client->request('GET', '/routeToApiController');
//we expect a 404 (from controller - not from api)
$this->assertEquals(404, $this->client->getResponse()->getStatusCode());
//we put controller's response in a variable
$result = \json_decode($this->client->getResponse()->getContent(), true);
//we check that controller give us what we expect
$this->assertEquals('error', $result['status']);
}
Test 3
In the last one we simulate a 500 answer.
<?php
public function testGenericError(): void
{
//we set up our API mock response
$response500 = new ClientResponse(Response::HTTP_INTERNAL_SERVER_ERROR);
$this->prepareMock($response500);
//we navigate to our route
$this->client->request('GET', '/routeToApiController');
//we expect a 500 (from controller - not from api)
$this->assertEquals(500, $this->client->getResponse()->getStatusCode());
//we put controller's response in a variable
$result = \json_decode($this->client->getResponse()->getContent(), true);
//we check that controller give us what we expect
$this->assertEquals('error', $result['status']);
$this->assertEquals('something went wrong', $result['message']);
}
That’s all folks!
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