Add milestone_title filter to EpicsFinder

-  Use a new method by_milestone in
EpicsFinder to fetch milestone from params
and filter epics that contain issues with
given milestone
- Add milestone_title argument to EpicsResolver
- Add Finder and Resolver specs for filtering by
milestone cases

Update GraphQL schema

Allow filtering by project milestones

Update milestone_title argument description

- Update GraphQL schema

Use hierarchy params to determine milestones

- If include_ancestor_groups or
include_descendant_groups params are present these
groups and their projects will be included in
MilestoneFinder

Add specs for filter by milestones with hierarchy

doc/api/graphql/reference/gitlab_schema.graphql

@@ -3708,6 +3708,11 @@ type Epic implements Noteable {
     """
     last: Int
 
+    """
+    Filter epics by milestone title, computed from epic's issues
+    """
+    milestoneTitle: String
+
     """
     Search query for epic title or description
     """
@@ -4995,6 +5000,11 @@ type Group {
     """
     labelName: [String!]
 
+    """
+    Filter epics by milestone title, computed from epic's issues
+    """
+    milestoneTitle: String
+
     """
     Search query for epic title or description
     """
@@ -5072,6 +5082,11 @@ type Group {
     """
     last: Int
 
+    """
+    Filter epics by milestone title, computed from epic's issues
+    """
+    milestoneTitle: String
+
     """
     Search query for epic title or description
     """

doc/api/graphql/reference/gitlab_schema.json

@@ -10376,6 +10376,16 @@
                   },
                   "defaultValue": null
                 },
+                {
+                  "name": "milestoneTitle",
+                  "description": "Filter epics by milestone title, computed from epic's issues",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
                 {
                   "name": "iidStartsWith",
                   "description": "Filter epics by iid for autocomplete",
@@ -13991,6 +14001,16 @@
                   },
                   "defaultValue": null
                 },
+                {
+                  "name": "milestoneTitle",
+                  "description": "Filter epics by milestone title, computed from epic's issues",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
                 {
                   "name": "iidStartsWith",
                   "description": "Filter epics by iid for autocomplete",
@@ -14120,6 +14140,16 @@
                   },
                   "defaultValue": null
                 },
+                {
+                  "name": "milestoneTitle",
+                  "description": "Filter epics by milestone title, computed from epic's issues",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
                 {
                   "name": "iidStartsWith",
                   "description": "Filter epics by iid for autocomplete",

ee/app/finders/epics_finder.rb

@@ -8,6 +8,7 @@
 #   author_id: integer
 #   author_username: string
 #   label_name: string
+#   milestone_title: string
 #   search: string
 #   sort: string
 #   start_date: datetime
@@ -33,6 +34,7 @@ class EpicsFinder < IssuableFinder
       author_id
       author_username
       label_name
+      milestone_title
       start_date
       end_date
       search
@@ -71,7 +73,6 @@ class EpicsFinder < IssuableFinder
     sort(items)
   end
 
-  # rubocop: disable CodeReuse/ActiveRecord
   def init_collection
     groups = if params[:iids].present?
                # If we are querying for specific iids, then we should only be looking at
@@ -82,21 +83,22 @@ class EpicsFinder < IssuableFinder
                permissioned_related_groups
              end
 
-    epics = Epic.where(group: groups)
+    epics = Epic.in_selected_groups(groups)
     with_confidentiality_access_check(epics, groups)
   end
-  # rubocop: enable CodeReuse/ActiveRecord
 
   private
 
   def permissioned_related_groups
-    groups = related_groups
+    strong_memoize(:permissioned_related_groups) do
+      groups = related_groups
 
-    # if user is member of top-level related group, he can automatically read
-    # all epics in all subgroups
-    return groups if can_read_all_epics_in_related_groups?(groups)
+      # if user is member of top-level related group, he can automatically read
+      # all epics in all subgroups
+      next groups if can_read_all_epics_in_related_groups?(groups)
 
-    groups_user_can_read_epics(groups)
+      groups_user_can_read_epics(groups)
+    end
   end
 
   def groups_user_can_read_epics(groups)
@@ -116,6 +118,7 @@ class EpicsFinder < IssuableFinder
     items = by_iids(items)
     items = by_my_reaction_emoji(items)
     items = by_confidential(items)
+    items = by_milestone(items)
 
     starts_with_iid(items)
   end
@@ -225,4 +228,19 @@ class EpicsFinder < IssuableFinder
 
     params[:confidential] ? items.confidential : items.public_only
   end
+
+  # rubocop: disable CodeReuse/ActiveRecord
+  def by_milestone(items)
+    return items unless params[:milestone_title].present?
+
+    milestones = Milestone.for_projects_and_groups(group_projects, permissioned_related_groups)
+                          .where(title: params[:milestone_title])
+
+    items.in_milestone(milestones)
+  end
+  # rubocop: enable CodeReuse/ActiveRecord
+
+  def group_projects
+    Project.in_namespace(permissioned_related_groups).with_issues_available_for_user(current_user)
+  end
 end

ee/app/graphql/resolvers/epics_resolver.rb

@@ -32,6 +32,10 @@ module Resolvers
              required: false,
              description: 'Filter epics by labels'
 
+    argument :milestone_title, GraphQL::STRING_TYPE,
+             required: false,
+             description: "Filter epics by milestone title, computed from epic's issues"
+
     argument :iid_starts_with, GraphQL::STRING_TYPE,
              required: false,
              description: 'Filter epics by iid for autocomplete'

ee/changelogs/unreleased/218621-roadmaps-filter-by-milestone.yml

+---
+title: Add the option to filter epics by milestone
+merge_request: 36193
+author:
+type: added

ee/spec/finders/epics_finder_spec.rb

@@ -261,6 +261,167 @@ RSpec.describe EpicsFinder do
           end
         end
 
+        context 'by milestone' do
+          let_it_be(:ancestor_group) { create(:group, :public) }
+          let_it_be(:ancestor_group_project) { create(:project, :public, group: ancestor_group) }
+          let_it_be(:base_group) { create(:group, :public, parent: ancestor_group) }
+          let_it_be(:base_group_project) { create(:project, :public, group: base_group) }
+          let_it_be(:base_epic1) { create(:epic, group: base_group) }
+          let_it_be(:base_epic2) { create(:epic, group: base_group) }
+          let_it_be(:base_group_milestone) { create(:milestone, group: base_group) }
+          let_it_be(:base_project_milestone) { create(:milestone, project: base_group_project) }
+          let_it_be(:project2) { base_group_project }
+
+          shared_examples 'filtered by milestone' do |milestone_type|
+            it 'returns expected epics' do
+              project3 = milestone_type == :group ? project2 : project
+
+              create(:issue, project: project, milestone: milestone, epic: epic)
+              create(:issue, project: project3, milestone: milestone, epic: epic2)
+
+              params[:milestone_title] = milestone.title
+
+              expect(epics(params)).to contain_exactly(epic, epic2)
+            end
+          end
+
+          context 'with no hierarchy' do
+            let_it_be(:project) { base_group_project }
+            let_it_be(:epic) { base_epic1 }
+            let_it_be(:epic2) { base_epic2 }
+            let_it_be(:params) do
+              {
+                  group_id: base_group.id,
+                  include_descendant_groups: false,
+                  include_ancestor_groups: false
+              }
+            end
+
+            it_behaves_like 'filtered by milestone', :group do
+              let_it_be(:milestone) { base_group_milestone }
+            end
+
+            it_behaves_like 'filtered by milestone', :project do
+              let_it_be(:milestone) { base_project_milestone }
+            end
+
+            it 'returns empty result if the milestone is not present' do
+              params[:milestone_title] = 'test milestone title'
+
+              expect(epics(params)).to be_empty
+            end
+          end
+
+          context "with hierarchy" do
+            let_it_be(:subgroup) { create(:group, :public, parent: base_group) }
+            let_it_be(:subgroup_project) { create(:project, :public, group: subgroup) }
+            let_it_be(:subgroup_project_milestone) { create(:milestone, project: subgroup_project) }
+            let_it_be(:ancestor_group_milestone) { create(:milestone, group: ancestor_group) }
+            let_it_be(:ancestor_project_milestone) { create(:milestone, project: ancestor_group_project) }
+            let_it_be(:subgroup_epic1) { create(:epic, group: subgroup) }
+            let_it_be(:subgroup_epic2) { create(:epic, group: subgroup) }
+            let_it_be(:ancestor_epic1) { create(:epic, group: ancestor_group) }
+            let_it_be(:ancestor_epic2) { create(:epic, group: ancestor_group) }
+            let_it_be(:params) { { group_id: base_group.id } }
+
+            context 'when include_descendant_groups is true' do
+              let_it_be(:project) { subgroup_project }
+              let_it_be(:epic) { subgroup_epic1 }
+              let_it_be(:epic2) { subgroup_epic2 }
+
+              before do
+                params[:include_descendant_groups] = true
+                params[:include_ancestor_groups] = false
+              end
+
+              it_behaves_like 'filtered by milestone', :group do
+                let(:milestone) { base_group_milestone }
+              end
+
+              it_behaves_like 'filtered by milestone', :project do
+                let(:milestone) { subgroup_project_milestone }
+              end
+
+              it 'returns results with all milestones matching given title' do
+                project_milestone1 = create(:milestone, project: base_group_project, title: '13.0')
+                project_milestone2 = create(:milestone, project: subgroup_project, title: '13.0')
+                create(:issue, project: base_group_project, milestone: project_milestone1, epic: base_epic1)
+                create(:issue, project: subgroup_project, milestone: project_milestone2, epic: subgroup_epic1)
+
+                params[:milestone_title] = '13.0'
+
+                expect(epics(params)).to contain_exactly(base_epic1, subgroup_epic1)
+              end
+            end
+
+            context 'when include_ancestor_groups is true' do
+              let_it_be(:project) { ancestor_group_project }
+              let_it_be(:epic) { ancestor_epic1 }
+              let_it_be(:epic2) { ancestor_epic2 }
+
+              before do
+                params[:include_descendant_groups] = false
+                params[:include_ancestor_groups] = true
+              end
+
+              it_behaves_like 'filtered by milestone', :group do
+                let(:milestone) { ancestor_group_milestone }
+              end
+
+              it_behaves_like 'filtered by milestone', :project do
+                let(:milestone) { ancestor_project_milestone }
+              end
+
+              context 'when include_descendant_groups is true' do
+                before do
+                  params[:include_descendant_groups] = true
+                end
+
+                it 'returns expected epics when filtering by group milestone' do
+                  create(:issue, project: ancestor_group_project, milestone: ancestor_group_milestone, epic: ancestor_epic1)
+                  create(:issue, project: base_group_project, milestone: ancestor_group_milestone, epic: ancestor_epic1)
+                  create(:issue, project: subgroup_project, milestone: ancestor_group_milestone, epic: subgroup_epic1)
+
+                  params[:milestone_title] = ancestor_group_milestone.title
+
+                  expect(epics(params)).to contain_exactly(ancestor_epic1, ancestor_epic1, subgroup_epic1)
+                end
+
+                it_behaves_like 'filtered by milestone', :project do
+                  let(:milestone) { ancestor_project_milestone }
+                end
+              end
+
+              context 'when a project is restricted' do
+                let_it_be(:issue) do
+                  create(:issue, project: subgroup_project,
+                    epic: subgroup_epic1,
+                    milestone: subgroup_project_milestone
+                  )
+                end
+
+                before do
+                  params[:milestone_title] = subgroup_project_milestone.title
+                end
+
+                it 'does not return epic if user can not access project' do
+                  subgroup_project
+                    .update!(visibility_level: Gitlab::VisibilityLevel::PRIVATE)
+
+                  expect(epics(params)).to be_empty
+                end
+
+                it 'does not return epics if user can not access project issues' do
+                  subgroup_project
+                    .project_feature.update!( issues_access_level: ProjectFeature::DISABLED)
+
+                  expect(epics(params)).to be_empty
+                end
+              end
+            end
+          end
+        end
+
         context 'when using iid starts with query' do
           let_it_be(:epic1) { create(:epic, :opened, group: group, iid: '11') }
           let_it_be(:epic2) { create(:epic, :opened, group: group, iid: '1112') }

ee/spec/graphql/resolvers/epics_resolver_spec.rb

@@ -9,7 +9,7 @@ RSpec.describe Resolvers::EpicsResolver do
   let_it_be(:user2) { create(:user) }
 
   context "with a group" do
-    let(:group)   { create(:group) }
+    let_it_be_with_refind(:group) { create(:group) }
     let(:project) { create(:project, :public, group: group) }
     let(:epic1)   { create(:epic, group: group, state: :closed, created_at: 3.days.ago, updated_at: 2.days.ago) }
     let(:epic2)   { create(:epic, group: group, author: user2, title: 'foo', description: 'bar', created_at: 2.days.ago, updated_at: 3.days.ago) }
@@ -134,6 +134,28 @@ RSpec.describe Resolvers::EpicsResolver do
         end
       end
 
+      context 'with milestone_title' do
+        let_it_be(:milestone1) { create(:milestone, group: group) }
+
+        it 'filters epics by issues milestone' do
+          create(:issue, project: project, epic: epic2)
+          create(:issue, project: project, milestone: milestone1, epic: epic1)
+
+          epics = resolve_epics(milestone_title: milestone1.title)
+
+          expect(epics).to match_array([epic1])
+        end
+
+        it 'returns empty result if milestone is not assigned to any epic issues' do
+          milestone2 = create(:milestone, group: group)
+          create(:issue, project: project, milestone: milestone1, epic: epic1)
+
+          epics = resolve_epics(milestone_title: milestone2.title)
+
+          expect(epics).to be_empty
+        end
+      end
+
       context 'with sort' do
         let!(:epic1) { create(:epic, group: group, title: 'first created', description: 'description', start_date: 10.days.ago, end_date: 10.days.from_now) }
         let!(:epic2) { create(:epic, group: group, title: 'second created', description: 'text 1', start_date: 20.days.ago, end_date: 20.days.from_now) }
@@ -181,6 +203,15 @@ RSpec.describe Resolvers::EpicsResolver do
         it 'return all epics' do
           expect(resolve_epics).to contain_exactly(epic1, epic2, epic3, epic4)
         end
+
+        it 'filter by milestones in subgroups' do
+          subgroup_project = create(:project, group: sub_group)
+          milestone = create(:milestone, group: sub_group)
+          create(:issue, project: subgroup_project, epic: epic1, milestone: milestone)
+          create(:issue, project: subgroup_project, epic: epic3, milestone: milestone)
+
+          expect(resolve_epics(milestone_title: milestone.title)).to contain_exactly(epic1, epic3)
+        end
       end
 
       context 'with partial iids' do