flux-querybuilder/tests/Functions/FilterFunctionTest.php

<?php
declare(strict_types=1);

use Arendsen\FluxQueryBuilder\Expression\KeyValue;
use Arendsen\FluxQueryBuilder\Functions\Filter;
use PHPUnit\Framework\TestCase;

final class FilterFunctionTest extends TestCase {

    public function testSimpleFilter()
    {
        $expression = new Filter(KeyValue::setEqualTo('_measurement', 'test_measurement')
            ->andEqualTo('_field', 'user')
            ->orEqualTo('_field', 'field2')
            ->andEqualTo('user', 'my_username')
        );

        $query = '|> filter(fn: (r) => r._measurement == "test_measurement" and r._field == "user" or ' . 
            'r._field == "field2" and r.user == "my_username") ';

        $this->assertEquals($expression->__toString(), $query);
    }

}