FIX: process new invites when existing users are already group members (#11971)

If a list of email addresses is pasted into a group’s Add Members form
that has one or more email addresses of users who already belong to the
group and all other email addresses are for users who do not yet exist
on the forum then no invites were being sent. This commit ensures that
we send invites to new users.

app/controllers/groups_controller.rb

@@ -351,7 +351,9 @@ class GroupsController < ApplicationController
     end
 
     usernames_already_in_group = group.users.where(id: users.map(&:id)).pluck(:username)
-    if usernames_already_in_group.present? && usernames_already_in_group.length == users.length
+    if usernames_already_in_group.present? &&
+      usernames_already_in_group.length == users.length &&
+      emails.blank?
       render_json_error(I18n.t(
         "groups.errors.member_already_exist",
         username: usernames_already_in_group.sort.join(", "),

spec/requests/groups_controller_spec.rb

@@ -1246,6 +1246,23 @@ describe GroupsController do
           expect(response.status).to eq(200)
         end
 
+        it 'sends invites to new users and ignores existing users' do
+          user1.update!(username: 'john')
+          user2.update!(username: 'alice')
+          [user1, user2].each { |user| group.add(user) }
+          emails = ["something@gmail.com", "anotherone@yahoo.com"]
+          put "/groups/#{group.id}/members.json",
+            params: { user_emails: [user1.email, user2.email].join(","), emails: emails.join(",") }
+
+          expect(response.status).to eq(200)
+          expect(response.parsed_body["emails"]).to eq(emails)
+
+          emails.each do |email|
+            invite = Invite.find_by(email: email)
+            expect(invite.groups).to eq([group])
+          end
+        end
+
         it 'displays warning when all members already exists' do
           user1.update!(username: 'john')
           user2.update!(username: 'alice')