fix #35161, add a first-time contributor badge

a new badge will be added when an user that doesn't yet
have any merged merge request is discussing on either issues or
merge requests that he created.

this is indented for people to use extra care when discussing with
a new contributor.

app/helpers/notes_helper.rb

@@ -76,6 +76,11 @@ module NotesHelper
     note.project.team.human_max_access(note.author_id)
   end
 
+  def note_first_contribution_for_user?(note)
+    note.noteable.author_id == note.author_id &&
+    note.project.merge_requests.merged.where(author_id: note.author_id).empty?
+  end
+
   def discussion_path(discussion)
     if discussion.for_merge_request?
       return unless discussion.diff_discussion?

app/views/projects/notes/_actions.html.haml

 - access = note_max_access_for_user(note)
 - if access
   %span.note-role= access
+- if note_first_contribution_for_user?(note)
+  %span.note-role.has-tooltip{ title: _("This user hasn't yet contributed code to this project. Handle with care.")}
+    = _('First-time contributor')
 
 - if note.resolvable?
   - can_resolve = can?(current_user, :resolve_note, note)

spec/helpers/notes_helper_spec.rb

@@ -39,6 +39,71 @@ describe NotesHelper do
     end
   end
 
+  describe '#note_first_contribution_for_user?' do
+    let(:project) { create(:empty_project) }
+    let(:other_project) { create(:empty_project) }
+
+    let(:contributor) { create(:user) }
+    let(:first_time_contributor) { create(:user) }
+
+    # there should be a way to disable the lazy loading on these
+    let(:merged_mr) { create(:merge_request, :merged, author: contributor, target_project: project, source_project: project) }
+    let(:open_mr) { create(:merge_request, author: first_time_contributor, target_project: project, source_project: project) }
+    let(:merged_mr_other_project) { create(:merge_request, :merged, author: first_time_contributor, target_project: other_project, source_project: other_project) }
+
+    context "notes for a merge request" do
+      let(:guest_merge_request) { create(:merge_request, author: guest, target_project: project, source_project: project) }
+      let(:contributor_note) { create(:note, noteable: merged_mr, author: contributor, project: merged_mr.project) }
+      let(:first_time_contributor_note) { create(:note, noteable: open_mr, author: first_time_contributor, project: open_mr.project) }
+      let(:first_time_contributor_note_other_project) { create(:note, noteable: merged_mr_other_project, author: first_time_contributor, project: merged_mr_other_project.project) }
+      let(:guest_note) { create(:note, noteable: guest_merge_request, author: first_time_contributor, project: project) }
+
+      it "is true when you don't have any merged MR" do
+        expect(helper.note_first_contribution_for_user? contributor_note).to be false
+        expect(helper.note_first_contribution_for_user? first_time_contributor_note).to be true
+      end
+
+      it "handle multiple projects separately" do
+        expect(helper.note_first_contribution_for_user? first_time_contributor_note).to be true
+        expect(helper.note_first_contribution_for_user? first_time_contributor_note_other_project).to be false
+      end
+
+      it "should only apply to the noteable's author" do
+        expect(helper.note_first_contribution_for_user? guest_note).to be false
+      end
+    end
+
+    context "notes for an issue" do
+      let(:guest_issue) { create(:issue, author: guest, project: project) }
+      let(:contributor_issue) { create(:issue, author: contributor, project: project) }
+      let(:first_time_contributor_issue) { create(:issue, author: first_time_contributor, project: project) }
+      let(:first_time_contributor_issue_other_project) { create(:issue, author: first_time_contributor, project: other_project) }
+        
+      let(:contributor_note) { create(:note, noteable: contributor_issue, author: contributor, project: project) }
+      let(:first_time_contributor_note) { create(:note, noteable: first_time_contributor_issue, author: first_time_contributor, project: project) }
+      let(:first_time_contributor_note_other_project) { create(:note, noteable: first_time_contributor_issue_other_project, author: first_time_contributor, project: other_project) }
+      let(:guest_note) { create(:note, noteable: guest_issue, author: first_time_contributor, project: project) }
+
+      it "is true when you don't have any merged MR" do
+        expect(merged_mr).to be
+        expect(helper.note_first_contribution_for_user? contributor_note).to be false
+        expect(helper.note_first_contribution_for_user? first_time_contributor_note).to be true
+      end
+
+      it "handle multiple projects separately" do
+        expect(merged_mr).to be
+        expect(merged_mr_other_project).to be
+        expect(helper.note_first_contribution_for_user? first_time_contributor_note).to be true
+        expect(helper.note_first_contribution_for_user? first_time_contributor_note_other_project).to be false
+      end
+
+      it "should only apply to the noteable's author" do
+        expect(merged_mr).to be
+        expect(helper.note_first_contribution_for_user? guest_note).to be false
+      end
+    end
+  end
+
   describe '#discussion_path' do
     let(:project) { create(:project, :repository) }