Add user caps to group's membership settings

Changelog: added
EE: true

app/views/groups/settings/_membership.html.haml

@@ -4,3 +4,4 @@
   = render 'shared/allow_request_access', form: f
 
 = render_if_exists 'groups/member_lock_setting', f: f, group: @group
+= render_if_exists 'groups/user_caps_setting', f: f, group: @group

ee/app/views/groups/_user_caps_setting.html.haml

+- return unless Feature.enabled?(:saas_user_caps, group.root_ancestor)
+- user_cap_docs_link_url = help_page_path("/user/admin_area/settings/sign_up_restrictions", anchor: "user-cap")
+- user_cap_docs_link_start = '<a href="%{url}" target="_blank" rel="noopener noreferrer">'.html_safe % { url: user_cap_docs_link_url }
+.form-group
+  = f.label :new_user_signups_cap, _('User cap'), class: 'gl-font-weight-bold'
+  .form-text.text-muted= html_escape(_('When the number of active users exceeds this number, additional users must be %{user_cap_docs_link_start}approved by an owner%{user_cap_docs_link_end}. Leave empty if you don\'t want to enforce approvals.')) % { user_cap_docs_link_start: user_cap_docs_link_start, user_cap_docs_link_end: '</a>'.html_safe }
+  = f.number_field :new_user_signups_cap, min: 1, class: 'form-control form-control-sm gl-form-input gl-w-full gl-mt-3'
+

ee/spec/features/groups/group_settings_spec.rb

@@ -408,6 +408,52 @@ RSpec.describe 'Edit group settings' do
     end
   end
 
+  describe 'user caps settings' do
+    context 'when :saas_user_caps feature flag is off' do
+      before do
+        stub_feature_flags(saas_user_caps: false)
+        visit edit_group_path(group)
+      end
+
+      it 'is not visible' do
+        expect(page).not_to have_content('User cap')
+      end
+    end
+
+    context 'when :saas_user_caps feature flag is on', :js do
+      let(:user_caps_selector) { '[name="group[new_user_signups_cap]"]' }
+
+      before do
+        stub_feature_flags(saas_user_caps: true)
+        visit edit_group_path(group)
+      end
+
+      it 'is visible' do
+        expect(page).to have_content('User cap')
+      end
+
+      it 'will save positive numbers' do
+        find(user_caps_selector).set(5)
+
+        click_button 'Save changes'
+        wait_for_requests
+
+        expect(page).to have_content("Group 'Foo bar' was successfully updated.")
+      end
+
+      it 'will not allow negative number' do
+        find(user_caps_selector).set(-5)
+
+        click_button 'Save changes'
+        expect(page).to have_content('This field is required.')
+
+        wait_for_requests
+
+        expect(page).not_to have_content("Group 'Foo bar' was successfully updated.")
+      end
+    end
+  end
+
   def save_permissions_group
     page.within('.gs-permissions') do
       click_button 'Save changes'

locale/gitlab.pot

@@ -37133,6 +37133,9 @@ msgstr ""
 msgid "User and IP rate limits"
 msgstr ""
 
+msgid "User cap"
+msgstr ""
+
 msgid "User created at"
 msgstr ""
 
@@ -38432,6 +38435,9 @@ msgstr ""
 msgid "When merge requests and commits in the default branch close, any issues they reference also close."
 msgstr ""
 
+msgid "When the number of active users exceeds this number, additional users must be %{user_cap_docs_link_start}approved by an owner%{user_cap_docs_link_end}. Leave empty if you don't want to enforce approvals."
+msgstr ""
+
 msgid "When this merge request is accepted"
 msgid_plural "When these merge requests are accepted"
 msgstr[0] ""