Fix faulty NOT logic for issuable array params

Fixes labels and assignees NOT params to remove issuables containing ANY
value in the list instead of ALL values in the list.

app/finders/issuable_finder.rb

@@ -314,17 +314,20 @@ class IssuableFinder
     params[:assignee_username].present?
   end
 
-  # rubocop: disable CodeReuse/ActiveRecord
   def assignee
-    return @assignee if defined?(@assignee)
+    assignees.first
+  end
 
-    @assignee =
+  # rubocop: disable CodeReuse/ActiveRecord
+  def assignees
+    strong_memoize(:assignees) do
       if assignee_id?
-        User.find_by(id: params[:assignee_id])
+        User.where(id: params[:assignee_id])
       elsif assignee_username?
-        User.find_by_username(params[:assignee_username])
+        User.where(username: params[:assignee_username])
       else
-        nil
+        User.none
+      end
     end
   end
   # rubocop: enable CodeReuse/ActiveRecord
@@ -415,7 +418,7 @@ class IssuableFinder
       # These are "helper" params that are required inside the NOT to get the right results. They usually come in
       # at the top-level params, but if they do come in inside the `:not` params, they should take precedence.
       not_helpers = params.slice(*NEGATABLE_PARAMS_HELPER_KEYS).merge(params[:not].slice(*NEGATABLE_PARAMS_HELPER_KEYS))
-      not_param = { key => value }.with_indifferent_access.merge(not_helpers)
+      not_param = { key => value }.with_indifferent_access.merge(not_helpers).merge(not_query: true)
 
       items_to_negate = self.class.new(current_user, not_param).execute
 
@@ -543,6 +546,8 @@ class IssuableFinder
   # rubocop: enable CodeReuse/ActiveRecord
 
   def by_assignee(items)
+    return items.assigned_to(assignees) if not_query? && assignees.any?
+
     if filter_by_no_assignee?
       items.unassigned
     elsif filter_by_any_assignee?
@@ -624,7 +629,7 @@ class IssuableFinder
       elsif filter_by_any_label?
         items.any_label
       else
-        items.with_label(label_names, params[:sort])
+        items.with_label(label_names, params[:sort], not_query: not_query?)
       end
 
     items
@@ -673,4 +678,8 @@ class IssuableFinder
   def min_access_level
     ProjectFeature.required_minimum_access_level(klass)
   end
+
+  def not_query?
+    !!params[:not_query]
+  end
 end

app/models/concerns/issuable.rb

@@ -108,7 +108,9 @@ module Issuable
       where("NOT EXISTS (SELECT TRUE FROM #{to_ability_name}_assignees WHERE #{to_ability_name}_id = #{to_ability_name}s.id)")
     end
     scope :assigned_to, ->(u) do
-      where("EXISTS (SELECT TRUE FROM #{to_ability_name}_assignees WHERE user_id = ? AND #{to_ability_name}_id = #{to_ability_name}s.id)", u.id)
+      assignees_table = Arel::Table.new("#{to_ability_name}_assignees")
+      sql = assignees_table.project('true').where(assignees_table[:user_id].in(u)).where(Arel::Nodes::SqlLiteral.new("#{to_ability_name}_id = #{to_ability_name}s.id"))
+      where("EXISTS (#{sql.to_sql})")
     end
     # rubocop:enable GitlabSecurity/SqlInjection
 
@@ -263,8 +265,9 @@ module Issuable
         .reorder(Gitlab::Database.nulls_last_order('highest_priority', direction))
     end
 
-    def with_label(title, sort = nil)
-      if title.is_a?(Array) && title.size > 1
+    def with_label(title, sort = nil, not_query: false)
+      multiple_labels = title.is_a?(Array) && title.size > 1
+      if multiple_labels && !not_query
         joins(:labels).where(labels: { title: title }).group(*grouping_columns(sort)).having("COUNT(DISTINCT labels.title) = #{title.size}")
       else
         joins(:labels).where(labels: { title: title })

ee/app/finders/ee/issues_finder.rb

@@ -49,9 +49,13 @@ module EE
       params[:weight].to_s.downcase == ::IssuesFinder::FILTER_ANY
     end
 
+    def assignee_ids?
+      params[:assignee_ids].present?
+    end
+
     override :by_assignee
     def by_assignee(items)
-      if assignees.any?
+      if assignees.any? && !not_query?
         assignees.each do |assignee|
           items = items.assigned_to(assignee)
         end
@@ -62,15 +66,14 @@ module EE
       super
     end
 
+    override :assignees
     # rubocop: disable CodeReuse/ActiveRecord
     def assignees
       strong_memoize(:assignees) do
-        if params[:assignee_ids]
+        if assignee_ids?
           ::User.where(id: params[:assignee_ids])
-        elsif params[:assignee_username]
-          ::User.where(username: params[:assignee_username])
         else
-          []
+          super
         end
       end
     end

ee/spec/finders/issues_finder_spec.rb

@@ -54,6 +54,27 @@ describe IssuesFinder do
         end
       end
 
+      context 'filter by username' do
+        let_it_be(:user3) { create(:user) }
+        let(:issuables) { issues }
+
+        before do
+          project2.add_developer(user3)
+          issue2.assignees = [user, user2]
+          issue3.assignees = [user2, user3]
+        end
+
+        it_behaves_like 'assignee username filter' do
+          let(:params) { { assignee_username: [user2.username, user3.username] } }
+          let(:expected_issuables) { [issue3] }
+        end
+
+        it_behaves_like 'assignee NOT username filter' do
+          let(:params) { { not: { assignee_username: [user.username, user2.username] } } }
+          let(:expected_issuables) { [issue4] }
+        end
+      end
+
       context 'filter by epic' do
         let_it_be(:group) { create(:group) }
 

spec/finders/issues_finder_spec.rb

@@ -33,17 +33,22 @@ describe IssuesFinder do
 
           before do
             project2.add_developer(user3)
-            issue3.assignees = [user2, user3]
+            issue2.assignees = [user2]
+            issue3.assignees = [user3]
           end
 
           it_behaves_like 'assignee username filter' do
-            let(:params) { { assignee_username: [user2.username, user3.username] } }
-            let(:expected_issuables) { [issue3] }
+            let(:params) { { assignee_username: [user2.username] } }
+            let(:expected_issuables) { [issue2] }
           end
 
           it_behaves_like 'assignee NOT username filter' do
-            let(:params) { { not: { assignee_username: [user2.username, user3.username] } } }
-            let(:expected_issuables) { [issue1, issue2, issue4] }
+            before do
+              issue2.assignees = [user2]
+            end
+
+            let(:params) { { not: { assignee_username: [user.username, user2.username] } } }
+            let(:expected_issuables) { [issue3, issue4] }
           end
         end
 
@@ -395,8 +400,8 @@ describe IssuesFinder do
         context 'using NOT' do
           let(:params) { { not: { label_name: [label.title, label2.title].join(',') } } }
 
-          it 'returns issues that do not have ALL labels provided' do
-            expect(issues).to contain_exactly(issue1, issue3, issue4)
+          it 'returns issues that do not have any of the labels provided' do
+            expect(issues).to contain_exactly(issue1, issue4)
           end
         end
       end
@@ -417,8 +422,8 @@ describe IssuesFinder do
         context 'using NOT' do
           let(:params) { { not: { label_name: [label.title, label2.title].join(',') } } }
 
-          it 'returns issues that do not have ALL labels provided' do
-            expect(issues).to contain_exactly(issue1, issue3, issue4)
+          it 'returns issues that do not have ANY ONE of the labels provided' do
+            expect(issues).to contain_exactly(issue1, issue4)
           end
         end
       end