Allow Member.add_user to handle access requesters

Changes include:

- Ensure Member.add_user is not called directly when not necessary
- New GroupMember.add_users_to_group to have the same abstraction level as for Project
- Refactor Member.add_user to take a source instead of an array of members
- Fix Rubocop offenses
- Always use Project#add_user instead of project.team.add_user
- Factorize users addition as members in Member.add_users_to_source
- Make access_level a keyword argument in GroupMember.add_users_to_group and ProjectMember.add_users_to_projects
- Destroy any requester before adding them as a member
- Improve the way we handle access requesters in Member.add_user
  Instead of removing the requester and creating a new member,
  we now simply accepts their access request. This way, they will
  receive a "access request granted" email.
- Fix error that was previously silently ignored
- Stop raising when access level is invalid in Member, let Rails validation do their work

Signed-off-by: Rémy Coutable <remy@rymai.me>

1 files changed, 16 insertions, 0 deletions

diff --git a/app/models/members/group_member.rb b/app/models/members/group_member.rb
index 2f13d339c89..1b54a85d064 100644
--- a/app/models/members/group_member.rb
+++ b/app/models/members/group_member.rb
@@ -12,6 +12,22 @@ class GroupMember < Member
     Gitlab::Access.options_with_owner
   end
 
+  def self.access_levels
+    Gitlab::Access.sym_options_with_owner
+  end
+
+  def self.add_users_to_group(group, users, access_level, current_user: nil, expires_at: nil)
+    self.transaction do
+      add_users_to_source(
+        group,
+        users,
+        access_level,
+        current_user: current_user,
+        expires_at: expires_at
+      )
+    end
+  end
+
   def group
     source
   end