Mocking services when testing with Mink? - symfony

Question

I'm working on an application now that has a decent amount of javascript (dynamic forms) that I want to test. I've decided on using PHPUnit Mink + ZombieJS.
I want to mock some services that communicate with external APIs, but I'm not finding any resources on how this can be done with using a testing framework like Mink. If I was using Symfony's built in WebTestCase, I would use a bundle like the
TestDoubleBundle, but it won't work for real world requests like those in Mink.
Are there any other solutions available for this? I wonder if the best approach is to create an "test" version of my API service and configure my test environment to load that service instead of the real one. The test service would respond to various API methods with pre-determined responses. The big downside is that it's not as flexible - I can't dynamically configure the expected responses from the API methods.

Answer 1

I struggled a bit while trying to work out how TestDoubleBundle works but actually it is very simple. I'll show you a working example which I hope it would be helpful for you.
Case study: Let's http://api.postcodes.io/postcodes/{postcode} API in real life to get full details of given postcode. If we provide a non-existent postcode it returns null.
Example below is trimmed down version so you'll need to go to Mocking external APIs with behat in symfony for the full version.
FULL EXAMPLE
services.yml
services:
app.service.postcode:
class: AppBundle\Service\PostcodeService
arguments:
- "#app.util.guzzle"
- "%postcodes_api%"
app.util.guzzle:
class: GuzzleHttp\Client
tags:
- { name: test_double }
PostcodeService
class PostcodeService
{
private $client;
private $apiUri;
public function __construct(
ClientInterface $client,
$apiUri
) {
$this->client = $client;
$this->apiUri = $apiUri;
}
public function get($postcode)
{
return $this->getDetails($postcode);
}
private function getDetails($postcode)
{
$details = null;
try {
/** #var Response $response */
$response = $this->client->request(Request::METHOD_GET, $this->apiUri.$postcode);
/** #var Stream $body */
$body = $response->getBody();
$details = $body->getContents();
} catch (ClientException $e) {
}
return $details;
}
}
FeatureContext
/**
* #param string $postcode
*
* #Given /^the Postcode API is available for "([^"]*)"$/
*/
public function thePostcodeApiIsAvailableFor($postcode)
{
$postcodesApi = $this->kernel->getContainer()->getParameter('postcodes_api').$postcode;
$response = new Response(200, [], '{"result":{"latitude":0.12345678,"longitude":-0.1234567}}');
$this->kernel
->getContainer()
->get('app.util.guzzle.prophecy')
->request(Request::METHOD_GET, $postcodesApi)
->willReturn($response);
}
Gherkin
Scenario: I get full result for existent postcode.
Given the Postcode API is available for "DUMMY POSTCODE"
When I send a "GET" request to "/postcodes/DUMMY POSTCODE"
Then the response status code should be 200
And the response should contain json:
"""
{"result":{"latitude":0.12345678,"longitude":-0.1234567}}
"""