<?php
class ApiTest extends PHPUnit_Framework_TestCase {
    private $CI;

    public function setUp() {
        $this->CI = &get_instance();
    }

    public function testVerifyFormat() {
        $data = array(
            "token" => "895c0d9b87d5ba256268f7238b61771e2b10291085ecb1015681817cb428fb66",
            "updated_registries" => 30
        );
        $expected = json_encode($data, true);

        $this->assertEquals(array_keys($data)[0], "token");
        $this->assertEquals(array_keys($data)[1], "updated_registries");
        $this->assertEquals(2, count($data));
    }
}

Fatal error: "Call to undefined function get_instance()" in C:xampphtdocsdevops_citestsApiTest.php on line 7