VSCode with PHP5

I'm struggling with setting up environment for old tech project with PHP5. My OS is Windows and I have installed so far VSCode plugins: PHP Debug, PHP Intelephense, PHPUnit, PHPUnit Test Explorer. I downloaded phpunit-5.7.27.phar and configured VSCode according to documentation.

Settings.json

{
    "php.validate.executablePath": "C:/wamp64/bin/php/php5.6.40/php.exe",
    "phpunit.phpunit": "C:/wamp64/bin/php/php5.6.40/phpunit-5.7.27.phar",
    "phpunit.php": "C:/wamp64/bin/php/php5.6.40/php.exe",
    "intelephense.environment.phpVersion": "5.6.40",
    "intelephense.environment.includePaths": [
        "C:/wamp64/bin/php/php5.6.40/phpunit-5.7.27.phar",
        "C:/wamp64/bin/php/php5.6.40/php.exe",
        "C:/wamp64/bin/php/php5.6.40/"
    ]

}

Launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Listen for XDebug",
            "type": "php",
            "request": "launch",
            "port": 9000,
            "xdebugSettings": {
                "max_children": 256,
                "max_data": 500,
                "max_depth": 3
            }
        },
    ]
}

What works for me fine is breakpointing on running app with xdebug and running unittests with Cmd+Shift+P.

What I need help with are as follows:

1. Code editor shows error for PHP unit classes and methods (even though unittests are executing fine as is). Do I need to add to path something besides phar file? Is VSCode non-compatible with phar files? The same happens for PHPUnit\Framework\TestCase.
2. I can't figure out how to configure Test Explorer plugin to show nicely tests tree. Does it require some configuration in Launch.json? Launching tests with Cmd+Shift+P displays results only in terminal.

1. PHP Intelephense requires installed PHPUnit with composer in workspace.

   composer require --dev phpunit/phpunit
   

2. PHPUnit Test Explorer has by default Phpunit: Files setting set to {test,tests}/**/*Test.php, so changing it to proper glob should allow plugin to detect all tests.