PHPUnit mocking request - class not found

Hello

I need to mock requests to a class with PHPUnit. I've noticed it is possible to mock a request thanks this post: https://forum.phalcon.io/discussion/1526/mocking-requests-for-unit-tests

However when I run the test I receive a message that the RequestMock class cannot be found. What am I doing wrong? I've tried adding the RequestMock class to the test namespace but that doesn't seem to help.

Test class:

<?php
namespace Phalcon\Test;

use Phalcon\Di;

/**
 * Class ControllerBaseTest
 */
class ControllerBaseTest extends \UnitTestCase {
  public function setUp(){
      parent::setUp();
      $this->di->set(
        "request",
        new Phalcon\Test\RequestMock()
      );
      $this->di->set(
        "response",
        "Phalcon\\Http\\Response"
      );
  }
}

RequestMock class:

<?php
namespace Phalcon\Test;

use Phalcon\Http\Request;

class RequestMock extends Phalcon\Http\Request
{
    /**
     * @var string|null Holds the raw body to be used for tests
     */
    static protected $raw_body = null;

    /**
     * Override the method to allow us to get a raw body, set for tests
     *
     * @return string
     */
    public function getRawBody()
    {
        return self::$raw_body;
    }

    /**
     * Sets the raw body to be used in tests
     *
     * @param string $raw_body The raw body to be set and used for tests
     */
    public function setRawBody($raw_body)
    {
        self::$raw_body = $raw_body;
    }
}

Error message:

[email protected]:/vagrant/www/ontrack/tests$ phpunit
PHPUnit 5.7.9 by Sebastian Bergmann and contributors.

Runtime:       PHP 5.6.29-1+deb.sury.org~trusty+1 with Xdebug 2.5.0
Configuration: /vagrant/www/ontrack/tests/phpunit.xml

.PHP Fatal error:  Class 'Phalcon\Test\Phalcon\Test\RequestMock' not found in /vagrant/www/ontrack/tests/app/controllers/api/ControllerBaseTest.php on line 16
PHP Stack trace:
PHP   1. {main}() /home/vagrant/.composer/vendor/phpunit/phpunit/phpunit:0
PHP   2. PHPUnit_TextUI_Command::main() /home/vagrant/.composer/vendor/phpunit/phpunit/phpunit:52
PHP   3. PHPUnit_TextUI_Command->run() /home/vagrant/.composer/vendor/phpunit/phpunit/src/TextUI/Command.php:118
PHP   4. PHPUnit_TextUI_TestRunner->doRun() /home/vagrant/.composer/vendor/phpunit/phpunit/src/TextUI/Command.php:188
PHP   5. PHPUnit_Framework_TestSuite->run() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/TextUI/TestRunner.php:491
PHP   6. PHPUnit_Framework_TestSuite->run() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestSuite.php:728
PHP   7. PHPUnit_Framework_TestCase->run() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestSuite.php:728
PHP   8. PHPUnit_Framework_TestResult->run() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestCase.php:927
PHP   9. PHPUnit_Framework_TestCase->runBare() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestResult.php:709
PHP  10. Phalcon\Test\ControllerBaseTest->setUp() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestCase.php:968

Fatal error: Class 'Phalcon\Test\Phalcon\Test\RequestMock' not found in /vagrant/www/ontrack/tests/app/controllers/api/ControllerBaseTest.php on line 16

Call Stack:
    0.0002     229472   1. {main}() /home/vagrant/.composer/vendor/phpunit/phpunit/phpunit:0
    0.0043     647760   2. PHPUnit_TextUI_Command::main() /home/vagrant/.composer/vendor/phpunit/phpunit/phpunit:52
    0.0043     648512   3. PHPUnit_TextUI_Command->run() /home/vagrant/.composer/vendor/phpunit/phpunit/src/TextUI/Command.php:118
    0.1189    3668464   4. PHPUnit_TextUI_TestRunner->doRun() /home/vagrant/.composer/vendor/phpunit/phpunit/src/TextUI/Command.php:188
    0.1648    4221920   5. PHPUnit_Framework_TestSuite->run() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/TextUI/TestRunner.php:491
    0.6650    5534296   6. PHPUnit_Framework_TestSuite->run() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestSuite.php:728
    0.6677    5537856   7. PHPUnit_Framework_TestCase->run() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestSuite.php:728
    0.6677    5538480   8. PHPUnit_Framework_TestResult->run() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestCase.php:927
    0.6701    5541152   9. PHPUnit_Framework_TestCase->runBare() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestResult.php:709
    0.6716    5558352  10. Phalcon\Test\ControllerBaseTest->setUp() /vagrant/www/ontrack/vendor/phpunit/phpunit/src/Framework/TestCase.php:968

[email protected]:/vagrant/www/ontrack/tests$

Folder structure:

- root
- - app
- - tests
- - - app
- - - - controllers
- - - - - api
- - - - - - ControllerBaseTest.php
- - - mocks
- - - - RequestMock.php 

Thanks in advance for any help! If you need more information/code. Please let me know and I'll happily provide it :)