Add non_archived param to filter issues

The param default value is true, returning
issues from non archived projects only.

changelogs/unreleased/28352-group-issues-api-searches-archived-projects.yml

+---
+title: Add non_archived param to issues API endpoint to filter issues from archived projects
+merge_request: 23785
+author:
+type: added

doc/api/issues.md

@@ -222,6 +222,7 @@ GET /groups/:id/issues?confidential=true
 | `updated_before`    | datetime         | no         | Return issues updated on or before the given time                                                                             |
 | `confidential`     | Boolean          | no         | Filter confidential or public issues.                                                                                         |
 | `not`               | Hash             | no         | Return issues that do not match the parameters supplied. Accepts: `labels`, `milestone`, `author_id`, `author_username`, `assignee_id`, `assignee_username`, `my_reaction_emoji`, `search`, `in` |
+| `non_archived`      | Boolean          | no         | Return issues from non archived projects. Default is true. _(Introduced in [GitLab 12.8](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/23785))_ |
 
 ```shell
 curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/groups/4/issues

lib/api/issues.rb

@@ -120,6 +120,7 @@ module API
       end
       params do
         use :issues_params
+        optional :non_archived, type: Boolean, desc: 'Return issues from non archived projects', default: true
       end
       get ":id/issues" do
         issues = paginate(find_issues(group_id: user_group.id, include_subgroups: true))

spec/requests/api/issues/issues_spec.rb

@@ -778,6 +778,32 @@ describe API::Issues do
           expect(json_response["error"]).to include("mutually exclusive")
         end
       end
+
+      context 'filtering by non_archived' do
+        let_it_be(:group1) { create(:group) }
+        let_it_be(:archived_project) { create(:project, :archived, namespace: group1) }
+        let_it_be(:active_project) { create(:project, namespace: group1) }
+        let_it_be(:issue1) { create(:issue, project: active_project) }
+        let_it_be(:issue2) { create(:issue, project: active_project) }
+        let_it_be(:issue3) { create(:issue, project: archived_project) }
+
+        before do
+          archived_project.add_developer(user)
+          active_project.add_developer(user)
+        end
+
+        it 'returns issues from non archived projects only by default' do
+          get api("/groups/#{group1.id}/issues", user), params: { scope: 'all' }
+
+          expect_response_contain_exactly(issue2, issue1)
+        end
+
+        it 'returns issues from archived and non archived projects when non_archived is false' do
+          get api("/groups/#{group1.id}/issues", user), params: { non_archived: false, scope: 'all' }
+
+          expect_response_contain_exactly(issue1, issue2, issue3)
+        end
+      end
     end
 
     context "when returns issue merge_requests_count for different access levels" do
@@ -862,4 +888,9 @@ describe API::Issues do
 
     include_examples 'time tracking endpoints', 'issue'
   end
+
+  def expect_response_contain_exactly(*items)
+    expect(json_response.length).to eq(items.size)
+    expect(json_response.map { |element| element['id'] }).to contain_exactly(*items.map(&:id))
+  end
 end