Laravel 5.6 Testing - No tests executed!

Hi, I've to rectify what I said in this post.

Premises

I'm using Laravel 5.6 within XAMPP in a Windows 10 machine. I've created from scratch a laravel application. At the beginning I've implemented a dusk testing, then I've deleted the folder and recreated (from backup).

I'm usign vendor/bin/phpunit, but I've also tried with vendor/phpunit/phpunit/phpunit. Same result.

Problem

I'm trying to set up some phpunit testing, but I received the message "No tests executed!".

Code

My Composer json:

{
    "name": "laravel/laravel",
    "description": "The Laravel Framework.",
    "keywords": ["framework", "laravel"],
    "license": "MIT",
    "type": "project",
    "require": {
        "php": "^7.1.3",
        "barryvdh/laravel-ide-helper": "^2.4",
        "fideloper/proxy": "^4.0",
        "laravel/browser-kit-testing": "4.0.x-dev",
        "laravel/dusk": "^3.0",
        "laravel/framework": "5.6.*",
        "laravel/tinker": "^1.0",
        "nexmo/client": "1.3.2",
        "nexmo/laravel": "1.1.1",
        "phpunit/phpunit": "7.1.5"
    },
    "require-dev": {
        "filp/whoops": "^2.0",
        "fzaninotto/faker": "^1.4",
        "mockery/mockery": "^1.0",
        "nunomaduro/collision": "^2.0"
    },
    "autoload": {
        "classmap": [
            "database/seeds",
            "database/factories"
        ],
        "psr-4": {
            "App\": "app/",
            "Todo\": "app/Repositories/Todo/"
        }
    },
    "autoload-dev": {
        "psr-4": {
            "Tests\": "tests/"
        }
    },
    "extra": {
        "laravel": {
            "dont-discover": [
            ]
        }
    },
    "scripts": {
        "post-root-package-install": [
            "@php -r \"file_exists('.env') || copy('.env.example', '.env');\""
        ],
        "post-create-project-cmd": [
            "@php artisan key:generate"
        ],
        "post-autoload-dump": [
            "Illuminate\Foundation\ComposerScripts::postAutoloadDump",
            "@php artisan package:discover"
        ]
    },
    "config": {
        "preferred-install": "dist",
        "sort-packages": true,
        "optimize-autoloader": true
    },
    "minimum-stability": "dev",
    "prefer-stable": true
}

My phpunit.xml:

<?xml version="1.0" encoding="UTF-8"?>
<phpunit verbose="true"
         bootstrap="vendor/autoload.php"
         colors="true"
         backupGlobals="false"
         backupStaticAttributes="false"
         convertErrorsToExceptions="true"
         convertNoticesToExceptions="true"
         convertWarningsToExceptions="true"
         processIsolation="false"
         stopOnFailure="false">

    <testsuites>
        <testsuite name="Unit">
            <directory suffix="Test.php">tests/Unit</directory>
        </testsuite>
        <testsuite name="Feature">
            <directory suffix="Test.php">tests/Feature</directory>
        </testsuite>
    </testsuites>

    <filter>
        <whitelist processUncoveredFilesFromWhitelist="true">
            <directory suffix=".php">./app</directory>
        </whitelist>
    </filter>
    <php>
        <env name="APP_ENV" value="testing"/>
        <env name="CACHE_DRIVER" value="array"/>
        <env name="SESSION_DRIVER" value="array"/>
        <env name="QUEUE_DRIVER" value="sync"/>
        <env name="MAIL_DRIVER" value="array"/>
        <env name="DB_CONNECTION" value="testing"/>
    </php>
</phpunit>

Other elements

It does not consider any of the test I've written: neither the basic one with assertTrue(true) nor the HTTP request test shown in the documentation (before I've said that this last one was working, but it is not). It does not execute them.

In this video guide on PHPUnit (not specifically for laravel), it does the test class by extending "PHPUnit_Framework_TestCase". I've tried and at least it considers the test functions and the assertTrue of course passes, but I cannot use this class because I want to use the TestCase with all the functionalities included for testing in Laravel.

Thanks for the help. Regards.