Fix #can_assign_epic? method

- Fix specs

ee/app/models/ee/issue.rb

@@ -150,7 +150,7 @@ module EE
     end
 
     def can_assign_epic?(user)
-      user&.can?(:admin_epic, project.group)
+      project.group&.feature_available?(:epics) && user&.can?(:admin_issue, project)
     end
 
     def can_be_promoted_to_epic?(user, group = nil)

ee/app/services/ee/issues/base_service.rb

@@ -48,15 +48,7 @@ module EE
 
       def epic_param(issue)
         epic_id = params.delete(:epic_id)
-        epic = params.delete(:epic) || find_epic(issue, epic_id)
-
-        return unless epic
-
-        unless can?(current_user, :admin_issue, issue)
-          raise ::Gitlab::Access::AccessDeniedError
-        end
-
-        epic
+        params.delete(:epic) || find_epic(issue, epic_id)
       end
 
       def find_epic(issue, epic_id)

ee/app/services/epic_issues/create_service.rb

@@ -36,14 +36,18 @@ module EpicIssues
     def linkable_issuables(issues)
       @linkable_issues ||= begin
         issues.select do |issue|
-          supports_epics?(issue) &&
-            can?(current_user, :admin_issue, issue) &&
-            issuable_group_descendants.include?(issue.project.group) &&
-            !previous_related_issuables.include?(issue)
+          linkable_issue?(issue)
         end
       end
     end
 
+    def linkable_issue?(issue)
+      issue.supports_epic? &&
+        issue.project.group&.feature_available?(:epics) &&
+        issuable_group_descendants.include?(issue.project.group) &&
+        !previous_related_issuables.include?(issue)
+    end
+
     def previous_related_issuables
       @related_issues ||= issuable.issues.to_a
     end
@@ -51,9 +55,5 @@ module EpicIssues
     def issuable_group_descendants
       @descendants ||= issuable.group.self_and_descendants
     end
-
-    def supports_epics?(issue)
-      issue.supports_epic? && issue.project.group&.feature_available?(:epics)
-    end
   end
 end

ee/spec/models/issue_spec.rb

@@ -816,15 +816,13 @@ RSpec.describe Issue do
         it 'returns false' do
           project.add_developer(user)
 
-          expect(subject).to be_falsey
+          expect(subject).to be_truthy
         end
       end
 
-      context 'when a user is a group member' do
-        it 'returns true' do
-          group.add_developer(user)
-
-          expect(subject).to be_truthy
+      context 'when a user is not a group member' do
+        it 'returns false' do
+          expect(subject).to be_falsey
         end
       end
     end

ee/spec/services/epic_issues/create_service_spec.rb

@@ -89,6 +89,10 @@ RSpec.describe EpicIssues::CreateService do
     context 'when epics feature is disabled' do
       subject { assign_issue([valid_reference]) }
 
+      before do
+        group.add_developer(user)
+      end
+
       include_examples 'returns an error'
     end
 
@@ -156,7 +160,7 @@ RSpec.describe EpicIssues::CreateService do
               # and we insert 5 issues instead of 1 which we do for control count
               expect { described_class.new(epic, user, params).execute }
                 .not_to exceed_query_limit(control_count)
-                .with_threshold(29)
+                .with_threshold(30)
             end
           end