fixed last group owner issue and added test

app/models/member.rb

@@ -81,13 +81,14 @@ class Member < ActiveRecord::Base
         member = members.build
         member.invite_email = user
       end
-
+      if !current_user || current_user.can?(:update_group_member, member)
         member.created_by ||= current_user
         member.access_level = access_level
 
         member.save
       end
     end
+  end
 
   def invite?
     self.invite_token.present?

features/groups.feature

@@ -60,6 +60,14 @@ Feature: Groups
     Then I should see "Mike" in team list as "Reporter"
 
   @javascript
+  Scenario: Ignore add user to group when is already Owner
+    Given gitlab user "Mike"
+    When I visit group "Owned" members page
+    And I click link "Add members"
+    When I select "Mike" as "Reporter"
+    Then I should see "Mike" in team list as "Owner"
+
+  @javascript
   Scenario: Invite user to group
     When I visit group "Owned" members page
     And I click link "Add members"

features/steps/groups.rb

@@ -48,6 +48,17 @@ class Spinach::Features::Groups < Spinach::FeatureSteps
     click_button "Add users to group"
   end
 
+  step 'I select "Mike" as "Master"' do
+    user = User.find_by(name: "Mike")
+
+    page.within ".users-group-form" do
+      select2(user.id, from: "#user_ids", multiple: true)
+      select "Master", from: "access_level"
+    end
+
+    click_button "Add users to group"
+  end
+
   step 'I should see "Mike" in team list as "Reporter"' do
     page.within '.well-list' do
       expect(page).to have_content('Mike')
@@ -55,6 +66,13 @@ class Spinach::Features::Groups < Spinach::FeatureSteps
     end
   end
 
+  step 'I should see "Mike" in team list as "Owner"' do
+    page.within '.well-list' do
+      expect(page).to have_content('Mike')
+      expect(page).to have_content('Owner')
+    end
+  end
+
   step 'I select "sjobs@apple.com" as "Reporter"' do
     page.within ".users-group-form" do
       select2("sjobs@apple.com", from: "#user_ids", multiple: true)