Fix negated epic param for issues

Allows users to filter issues not included in an epic.

app/finders/issuable_finder.rb

@@ -102,7 +102,7 @@ class IssuableFinder
     items = filter_items(items)
 
     # Let's see if we have to negate anything
-    items = filter_negated_items(items)
+    items = filter_negated_items(items) if should_filter_negated_args?
 
     # This has to be last as we use a CTE as an optimization fence
     # for counts by passing the force_cte param and passing the
@@ -134,13 +134,15 @@ class IssuableFinder
     by_my_reaction_emoji(items)
   end
 
-  # Negates all params found in `negatable_params`
-  def filter_negated_items(items)
-    return items unless Feature.enabled?(:not_issuable_queries, params.group || params.project, default_enabled: true)
+  def should_filter_negated_args?
+    return false unless Feature.enabled?(:not_issuable_queries, params.group || params.project, default_enabled: true)
 
     # API endpoints send in `nil` values so we test if there are any non-nil
-    return items unless not_params.present? && not_params.values.any?
+    not_params.present? && not_params.values.any?
+  end
 
+  # Negates all params found in `negatable_params`
+  def filter_negated_items(items)
     items = by_negated_author(items)
     items = by_negated_assignee(items)
     items = by_negated_label(items)

ee/app/finders/ee/issues_finder.rb

@@ -75,5 +75,18 @@ module EE
         items.in_iterations(params.iterations)
       end
     end
+
+    override :filter_negated_items
+    def filter_negated_items(items)
+      items = by_negated_epic(items)
+
+      super(items)
+    end
+
+    def by_negated_epic(items)
+      return items unless not_params[:epic_id].present?
+
+      items.not_in_epics(not_params[:epic_id].to_i)
+    end
   end
 end

ee/app/models/ee/issue.rb

@@ -26,6 +26,7 @@ module EE
       scope :no_epic, -> { left_outer_joins(:epic_issue).where(epic_issues: { epic_id: nil }) }
       scope :any_epic, -> { joins(:epic_issue) }
       scope :in_epics, ->(epics) { joins(:epic_issue).where(epic_issues: { epic_id: epics }) }
+      scope :not_in_epics, ->(epics) { left_outer_joins(:epic_issue).where('epic_issues.epic_id NOT IN (?) OR epic_issues.epic_id IS NULL', epics) }
       scope :no_iteration, -> { where(sprint_id: nil) }
       scope :any_iteration, -> { where.not(sprint_id: nil) }
       scope :in_iterations, ->(iterations) { where(sprint_id: iterations) }

ee/changelogs/unreleased/negated_filter.yml

+---
+title: Fix issue filtering by negated epic parameter
+merge_request: 44719
+author:
+type: fixed

ee/spec/features/issues/filtered_search/filter_issues_epic_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'Filter issues by epic', :js do
+  include FilteredSearchHelpers
+
+  let_it_be(:group) { create(:group) }
+  let_it_be(:project) { create(:project, group: group) }
+  let_it_be(:user) { create(:user) }
+  let_it_be(:issue1) { create(:issue, project: project) }
+  let_it_be(:issue2) { create(:issue, project: project) }
+  let_it_be(:issue3) { create(:issue, project: project) }
+  let_it_be(:issue4) { create(:issue, project: project) }
+  let_it_be(:epic1) { create(:epic) }
+  let_it_be(:epic2) { create(:epic) }
+  let_it_be(:epic_issue1) { create(:epic_issue, issue: issue1, epic: epic1) }
+  let_it_be(:epic_issue2) { create(:epic_issue, issue: issue2, epic: epic2) }
+  let_it_be(:epic_issue3) { create(:epic_issue, issue: issue3, epic: epic2) }
+
+  let(:js_dropdown) { '#js-dropdown-epic' }
+
+  before do
+    stub_licensed_features(epics: true)
+    stub_feature_flags(vue_issuables_list: false)
+    project.add_developer(user)
+
+    sign_in(user)
+    visit project_issues_path(project)
+  end
+
+  it 'filter issues by epic' do
+    input_filtered_search("epic:=&#{epic1.id}")
+
+    expect_issues_list_count(1)
+  end
+
+  it 'filter issues not in the epic' do
+    input_filtered_search("epic:!=&#{epic1.id}")
+
+    expect_issues_list_count(3)
+  end
+end

ee/spec/finders/issues_finder_spec.rb

@@ -121,6 +121,14 @@ RSpec.describe IssuesFinder do
             expect(issues).to contain_exactly(issue_1, issue_2, issue_subepic)
           end
         end
+
+        context 'filter issues not in the epic' do
+          let(:params) { { not: { epic_id: epic_1.id } } }
+
+          it 'returns issues not assigned to the epic' do
+            expect(issues).to contain_exactly(issue1, issue2, issue3, issue4, issue_2, issue_subepic)
+          end
+        end
       end
 
       context 'filter by iteration' do

ee/spec/models/issue_spec.rb

@@ -132,6 +132,13 @@ RSpec.describe Issue do
         end
       end
 
+      describe '.not_in_epics' do
+        it 'returns only issues not in selected epics' do
+          expect(described_class.count).to eq 3
+          expect(described_class.not_in_epics([epic1])).to match_array([epic_issue2.issue, issue_no_epic])
+        end
+      end
+
       describe '.distinct_epic_ids' do
         it 'returns distinct epic ids' do
           expect(described_class.distinct_epic_ids.map(&:epic_id)).to match_array([epic1.id, epic2.id])