How can I programmatically add members to a group?

Question

I am trying add members to a group programmatically using Groups module in Drupal 8, and I am doing the following to achieve this:

use Drupal\Core\Entity\ContentEntityBase;
$roles = array('test_role');
$values = ['group_roles' => $roles, 'gid' => 1];
$account = $this->createUser();
$group = \Drupal\group\Entity\Group::load(1);
$group->addMember($account, $values);

So, users are already present in the site. I want to add only those users to a group who have successfully paid for it. Hence, I am trying to write a custom solution that I add a user to an already existing group on the site. I came across this addMember($account, $values) function in the group module, however am still not sure on what values its arguments ($account and $values) take. Above piece of code does not add users to my group. Can someone please suggest what wrong I am doing here?

Answer 1

So, modifying the code a little bit and saving the group after adding member to it worked for me. Pasting the updated code below:

use Drupal\Core\Entity\ContentEntityBase;
$account = \Drupal\user\Entity\User::load(\Drupal::currentUser()->id());
$group = \Drupal\group\Entity\Group::load($group_id);
$group->addMember($account);
$group->save();

Answer 2

Without 'gid' code below works for me:

$user = \Drupal\user\Entity\User::load(\Drupal::currentUser()->id());
$group = \Drupal::entityTypeManager()->getStorage('group')->load(127);
$group->addMember($user, ['group_roles' => ['podrazdelenie-admin']]);
$group->save();