Block features by issue type

Block features based on issue type. Allows certain UI elements, quick
actions and other features to be filtered for issue types.

app/models/concerns/issue_available_features.rb

+# frozen_string_literal: true
+
+# Verifies features availability based on issue type.
+# This can be used, for example, for hiding UI elements or blocking specific
+# quick actions for particular issue types;
+module IssueAvailableFeatures
+  extend ActiveSupport::Concern
+
+  # EE only features are listed on EE::IssueAvailableFeatures
+  def available_features_for_issue_types
+    {}.with_indifferent_access
+  end
+
+  def issue_type_supports?(feature)
+    unless available_features_for_issue_types.has_key?(feature)
+      raise ArgumentError, 'invalid feature'
+    end
+
+    available_features_for_issue_types[feature].include?(issue_type)
+  end
+end
+
+IssueAvailableFeatures.prepend_if_ee('EE::IssueAvailableFeatures')

app/models/issue.rb

@@ -20,6 +20,7 @@ class Issue < ApplicationRecord
   include StateEventable
   include IdInOrdered
   include Presentable
+  include IssueAvailableFeatures
 
   DueDateStruct                   = Struct.new(:title, :name).freeze
   NoDueDate                       = DueDateStruct.new('No Due Date', '0').freeze

ee/app/models/concerns/ee/issuable.rb

@@ -6,7 +6,7 @@ module EE
     extend ::Gitlab::Utils::Override
 
     def supports_epic?
-      is_a?(Issue) && !incident? && project.group.present?
+      is_a?(Issue) && issue_type_supports?(:epics) && project.group.present?
     end
 
     def supports_health_status?

ee/app/models/concerns/ee/issue_available_features.rb

+# frozen_string_literal: true
+
+module EE
+  module IssueAvailableFeatures
+    include ::Gitlab::Utils::StrongMemoize
+    extend ::Gitlab::Utils::Override
+
+    override :available_features_for_issue_types
+    def available_features_for_issue_types
+      strong_memoize(:available_features_for_issue_types) do
+        super.merge(epics: %w(issue))
+      end
+    end
+  end
+end

ee/spec/models/issue_spec.rb

@@ -758,4 +758,16 @@ RSpec.describe Issue do
       it { is_expected.to eq(supports_iterations) }
     end
   end
+
+  describe '#issue_type_supports?' do
+    let_it_be(:issue) { create(:issue) }
+    let_it_be(:test_case) { create(:quality_test_case) }
+    let_it_be(:incident) { create(:incident) }
+
+    it do
+      expect(issue.issue_type_supports?(:epics)).to be(true)
+      expect(test_case.issue_type_supports?(:epics)).to be(false)
+      expect(incident.issue_type_supports?(:epics)).to be(false)
+    end
+  end
 end

ee/spec/services/ee/notes/quick_actions_service_spec.rb

@@ -121,6 +121,16 @@ RSpec.describe Notes::QuickActionsService do
         end
       end
 
+      context 'on a test case' do
+        before do
+          issue.update!(issue_type: :test_case)
+        end
+
+        it 'leaves the note empty' do
+          expect(execute(note)).to be_empty
+        end
+      end
+
       context 'on a merge request' do
         let(:note_mr) { create(:note_on_merge_request, project: project, note: note_text) }
 

ee/spec/services/epics/issue_promote_service_spec.rb

@@ -168,14 +168,30 @@ RSpec.describe Epics::IssuePromoteService do
           end
         end
 
-        context 'on an incident' do
-          it 'raises error' do
-            issue.update!(issue_type: :incident)
+        context 'on other issue types' do
+          shared_examples_for 'raising error' do
+            before do
+              issue.update(issue_type: issue_type)
+            end
 
+            it 'raises error' do
               expect { subject.execute(issue) }
                 .to raise_error(Epics::IssuePromoteService::PromoteError, /is not supported/)
             end
           end
+
+          context 'on an incident' do
+            let(:issue_type) { :incident }
+
+            it_behaves_like 'raising error'
+          end
+
+          context 'on a test case' do
+            let(:issue_type) { :test_case }
+
+            it_behaves_like 'raising error'
+          end
+        end
       end
     end
   end

spec/models/issue_spec.rb

@@ -1238,4 +1238,12 @@ RSpec.describe Issue do
       expect(issue.allows_reviewers?).to be(false)
     end
   end
+
+  describe '#issue_type_supports?' do
+    let_it_be(:issue) { create(:issue) }
+
+    it 'raises error when feature is invalid' do
+      expect { issue.issue_type_supports?(:unkown_feature) }.to raise_error(ArgumentError)
+    end
+  end
 end