Fix Symfony 3.4 Deprecated warnings PHPUnit

Symfony 3.4 is no longer actively supported as of November 2021. However, if you encounter deprecated warnings when running PHPUnit tests in Symfony 3.4, you can try the following steps to fix them:

1. Update PHPUnit Version: Symfony 3.4 may come with an older version of PHPUnit, which can lead to deprecated warnings. Check the current version of PHPUnit required by Symfony 3.4 in the composer.json file and make sure you are using a compatible PHPUnit version. You can update the PHPUnit version in the composer.json file and run composer update to install the latest compatible version.

   For example, update the "phpunit/phpunit" package to a compatible version:

   jsonCopy code
   "require-dev": {
       "phpunit/phpunit": "^X.Y.Z"
   }
   

2. Check Symfony Deprecation Notices: Before updating PHPUnit, run your tests with the SYMFONY_DEPRECATIONS_HELPER environment variable set to "weak" or "disabled". This will help identify if the deprecated warnings are related to Symfony deprecations rather than PHPUnit. Deprecation notices from Symfony components will be displayed in the test output. Fix any Symfony-related deprecations by updating your code accordingly.

   For example, to run tests with the deprecation helper set to "weak":

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   SYMFONY_DEPRECATIONS_HELPER=weak ./vendor/bin/phpunit
   

3. Update Test Code: Review your test code and update any usages of deprecated PHPUnit features or methods. PHPUnit often introduces changes between versions, and it's important to use the correct methods for your PHPUnit version.

4. Check Third-Party Libraries: If your project uses third-party libraries, make sure they are compatible with Symfony 3.4 and the updated PHPUnit version. Check the documentation and release notes of the third-party libraries for any required updates.

5. Run PHPUnit with Debug Mode: Running PHPUnit with the --debug option can provide additional information about the deprecated warnings and help pinpoint their sources.

   For example:

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   ./vendor/bin/phpunit --debug
   

6. Fix Deprecated Symfony Components: If the deprecated warnings are related to Symfony components, update your code to use the non-deprecated alternatives. Symfony's official documentation and release notes can help you find the correct replacements.

7. Consider Upgrading Symfony: Symfony 3.4 has reached its end of life, and it's recommended to upgrade to a supported version (e.g., Symfony 4.4, Symfony 5.x, or later) to receive security updates and bug fixes. Upgrading to a supported version will also help you avoid deprecated warnings in the future.

Remember to test your application thoroughly after making any changes to ensure everything works as expected.

Please note that Symfony 3.4-specific fixes may not be actively maintained or updated. It's generally advisable to consider upgrading to a supported Symfony version for long-term support and security updates.