<?php
namespace Tests\Unit;
use PHPUnit\Framework\TestCase;
class DistrictKindTest extends TestCase
{
    /**
     * Index method unit test.
     *
     * @return void
     */
    public function test_index()
    {
        $response = $this->json('GET', '/api/distinct-kinds');
        $response->assertStatus(200);
    }
}

PHPUnit 9.6.3 by Sebastian Bergmann and contributors.
E....                                                               5 / 5 (100%)
Time: 00:00.151, Memory: 20.00 MB
There was 1 error:
1) Tests\Unit\DistrictKindTest::test_index
Error: Call to undefined method Tests\Unit\DistrictKindTest::json()
/var/www/html/tests/Unit/DistrictKindTest.php:23
ERRORS!
Tests: 5, Assertions: 13, Errors: 1.

use Tests\TestCase;