Show create merge request button on confidential issues

https://gitlab.com/gitlab-org/gitlab-ce/issues/58583

app/helpers/issues_helper.rb

@@ -135,6 +135,20 @@ module IssuesHelper
     can?(current_user, :create_issue, project)
   end
+  def create_confidential_merge_request_enabled?
+    Feature.enabled?(:create_confidential_merge_request, @project)
+  end
+
+  def show_new_branch_button?
+    can_create_confidential_merge_request? || !@issue.confidential?
+  end
+
+  def can_create_confidential_merge_request?
+    @issue.confidential? && !@project.private? &&
+      create_confidential_merge_request_enabled? &&
+      can?(current_user, :create_merge_request_in, @project)
+  end
+
   # Required for Banzai::Filter::IssueReferenceFilter
   module_function :url_for_issue
   module_function :url_for_internal_issue

app/views/projects/issues/_new_branch.html.haml

@@ -2,6 +2,7 @@
   - can_create_merge_request = can?(current_user, :create_merge_request_in, @project)
   - data_action = can_create_merge_request ? 'create-mr' : 'create-branch'
   - value = can_create_merge_request ? 'Create merge request' : 'Create branch'
+  - value = can_create_confidential_merge_request? ? _('Create confidential merge request') : value
   - can_create_path = can_create_branch_project_issue_path(@project, @issue)
   - create_mr_path = create_merge_request_project_issue_path(@project, @issue, branch_name: @issue.to_branch_name, ref: @project.default_branch)
@@ -23,12 +24,15 @@
         = icon('caret-down')
       .droplab-dropdown
-        %ul#create-merge-request-dropdown.create-merge-request-dropdown-menu.dropdown-menu.dropdown-menu-right.gl-show-field-errors{ data: { dropdown: true } }
+        %ul#create-merge-request-dropdown.create-merge-request-dropdown-menu.dropdown-menu.dropdown-menu-right.gl-show-field-errors{ class: ("create-confidential-merge-request-dropdown-menu" if can_create_confidential_merge_request?), data: { dropdown: true } }
           - if can_create_merge_request
             %li.droplab-item-selected{ role: 'button', data: { value: 'create-mr', text: _('Create merge request') } }
               .menu-item
                 = icon('check', class: 'icon')
-                = _('Create merge request and branch')
+                - if can_create_confidential_merge_request?
+                  = _('Create confidential merge request and branch')
+                - else
+                  = _('Create merge request and branch')
           %li{ class: [!can_create_merge_request && 'droplab-item-selected'], role: 'button', data: { value: 'create-branch', text: _('Create branch') } }
             .menu-item

app/views/projects/issues/show.html.haml

@@ -91,7 +91,7 @@
         = render 'award_emoji/awards_block', awardable: @issue, inline: true
       .col-md-12.col-lg-6.new-branch-col
         #js-vue-discussion-filter{ data: { default_filter: current_user&.notes_filter_for(@issue), notes_filters: UserPreference.notes_filters.to_json } }
-        = render 'new_branch' unless @issue.confidential?
+        = render 'new_branch' if show_new_branch_button?
   = render_if_exists 'projects/issues/discussion'

locale/gitlab.pot

@@ -3056,6 +3056,12 @@ msgstr ""
 msgid "Create commit"
 msgstr ""
+msgid "Create confidential merge request"
+msgstr ""
+
+msgid "Create confidential merge request and branch"
+msgstr ""
+
 msgid "Create directory"
 msgstr ""

spec/features/issues/user_creates_branch_and_merge_request_spec.rb

@@ -3,7 +3,7 @@ require 'rails_helper'
 describe 'User creates branch and merge request on issue page', :js do
   let(:membership_level) { :developer }
   let(:user) { create(:user) }
-  let!(:project) { create(:project, :repository) }
+  let!(:project) { create(:project, :repository, :public) }
   let(:issue) { create(:issue, project: project, title: 'Cherry-Coloured Funk') }
   context 'when signed out' do
@@ -163,10 +163,21 @@ describe 'User creates branch and merge request on issue page', :js do
       let(:issue) { create(:issue, :confidential, project: project) }
       it 'disables the create branch button' do
+        stub_feature_flags(create_confidential_merge_request: false)
+
         visit project_issue_path(project, issue)
         expect(page).not_to have_css('.create-mr-dropdown-wrap')
       end
+
+      it 'enables the create branch button when feature flag is enabled' do
+        stub_feature_flags(create_confidential_merge_request: true)
+
+        visit project_issue_path(project, issue)
+
+        expect(page).to have_css('.create-mr-dropdown-wrap')
+        expect(page).to have_button('Create confidential merge request')
+      end
     end
     context 'when related branch exists' do