Tree builder without a root node deprecated since Symfony 4.2 during functional tests

Question

I'm setting up a Symfony 4.2.2 application, and I want to run functional tests with Gitlab-CI. But I'm facing this issue:

A tree builder without a root node is deprecated since Symfony 4.2 and will not be supported anymore in 5.0.

The strange thing is I've got this issue localy but only the first time I run unit tests after a cache rebuild. The second time I run unit tests, the error is not triggered anymore.

I'm using version 5.2.4 of sensio/framework-extra-bundle which should have fix the issue, as said here.

This error makes my job fail everytime, even though all tests are OK.

I made sure to use the class Symfony\Bundle\FrameworkBundle\Test\WebTestCase in my functional tests. I also made sure to have all my dependencies up to date.

Here is an example of a functional test I wrote:

<?php

namespace App\Tests\Controller;

use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;

/**
 * Class MigrationControllerTest
 *
 * @group functional
 */
class MigrationControllerTest extends WebTestCase
{
    public function testNotAllowed()
    {
        $client = static::createClient();

        $client->request('UPDATE', '/migrate');
        $this->assertEquals(405, $client->getResponse()->getStatusCode());
    }
}

And here is my CI config:

image: my.private.repo/images/php/7.2/symfony:latest

cache:
  paths:
    - vendor/

before_script:
  - composer install

services:
  - mysql:5.7

unit_test:
  script:
    # Set up database
    - bin/console doctrine:schema:update --env=test --force
    # Load fixtures
    - bin/console doctrine:fixtures:load --env=test --no-interaction
    # Build assets with Webpack Encore
    - npm install
    - npm run build
    # Enable xdebug for code coverage
    - docker-php-ext-enable xdebug
    # Run unit tests
    - php bin/phpunit --coverage-text --colors=never

I expect the output to show all tests passed, but the actual output is:

PHPUnit 6.5.14 by Sebastian Bergmann and contributors.

Testing Project Test Suite
.2019-02-04T14:48:29+01:00 [error] Uncaught PHP Exception Symfony\Component\HttpKernel\Exception\MethodNotAllowedHttpException: "No route found for "UPDATE /migrate": Method Not Allowed (Allow: GET, POST)" at /home/goulven/PhpStorm/user-balancer/vendor/symfony/http-kernel/EventListener/RouterListener.php line 143
.........                                                        10 / 10 (100%)

Time: 8.44 seconds, Memory: 52.25MB

OK (10 tests, 17 assertions)

Remaining deprecation notices (4)

  4x: A tree builder without a root node is deprecated since Symfony 4.2 and will not be supported anymore in 5.0.
    4x in MigrationControllerTest::testMigrateFail from App\Tests\Controller

Answer 1

Thanks to @SergheiNiculaev, I just added the following line in phpunit.xml.dist file:

<env name="SYMFONY_DEPRECATIONS_HELPER" value="weak"/>

[EDIT] Another solution consists in adding the following line in the CI config file:

variables:
  # ...
  SYMFONY_DEPRECATIONS_HELPER: weak