README.md

Composer.json:

"phpunit/phpunit": "^6",

PHPUnit

Test extends PHPUnit's TestCase which extends the Assert class.

MyTest.php

<?php

namespace Tests;

use PHPUnit\Framework\TestCase;

class MyTest extends TestCase
{
    public function test_it_does_something()
    {
        // Every one of these should provide code completion,
        // but show "not found" warnings. When running this in
        // my test suite, all work as expected.
        static::assertEquals(true, true);
        self::assertEquals(true, true);
        $this->assertEquals(true, true);
    }
}