THIS PACKAGE IS ABANDONNED

To replace a service of the Symfony container with a mock make a public alias on the service and then you're able to set a mock for it in the test case (if you have access to the container which is the case in ̀Symfony's KernelTestCase).

config/services.yaml

services:
    my.service:
        class: My\Service

config/services_test.yaml

services:
    my.service.test:
        alias: my.service
        public: true

Your test case extends KernelTestCase

use My\Service;
use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;

final class ConsumeUserMessagesFromCoreTest extends KernelTestCase
{
    public function testSomething(): void
    {
        // Access the service over the public alias defined in "services_test.yaml"
        self::$container->set('my.service.test', $this->getMockBuilder(Service::class)->getMock());
    }
}

This library helps to create a proxy instance of a class which then can hold a PHPUnit mock of it. That way you can manipulate the mock which sits inside the proxy class but never have to change the proxy class.

This can be useful for example in cases of read-only containers where you can't override services at runtime. (The dependency injection container component of Symfony 4 will most likely behave like that.)

class Foo { ... }

$factory = new ProxyMockFactory();
$proxyMock = $factory->create(Foo::class);

// In a PHPUnit test case
$mock = $this->getMockBuilder(Foo::class)
    ->disableOriginalConstructor()
    ->getMock();

$proxyMock->setMock($mock);