use SymfonyComponentHttpFoundationRequest;

class MyService
{
    public function doSomething(Request $request)
    {
        $foo = $request->query->get('foo');
        // ...
    }
}

use SymfonyComponentHttpFoundationRequest;

class MyServiceTest
{
    public function testSomething()
    {
        $service = new MyService();
        $request = new Request(array('foo' => 'bar'));
        $service->doSomething($request);
        // ...
    }
}

class MyService
{
    public function doSomething($foo)
    {
        // ...
    }
}

$service = new MyService();
$service->doSomething($request->query->get('foo');