AuthCest.java

class AuthCest
{
    // tests
    public function validCredentials(ApiTester $I)
    {
        $I->wantTo('Generate access token');
        $email = uniqid('email-') . '@gmail.com';
        $password = uniqid('password-');
        // create user in database
        $userId = $I->createUser([
            'email' => $email,
            'password' => $password
        ]);
        // generate access token via API
        $I->haveHttpHeader('Content-Type', 'application/json');
        $I->sendPOST('/api/v1/auth/authenticate', ['email' => $email, 'password' => $password]);
        // validate response
        $I->seeResponseCodeIs(\Codeception\Util\HttpCode::OK);
        $I->seeResponseIsJson();
        $I->seeResponseJsonMatchesJsonPath('$.token');
        $I->seeResponseJsonMatchesJsonPath('$.userId');
    }
}