Ability to distinguish if user is Gitlab employee

Adds an instance method on the user model to determine
whether the user is a GitLab employee or not.

It also exposes the is_gitlab_employee attribute in the
UserBasic entity used in discussion api to use
this detail to show a GitLab badge to discussion entities
of the company's employees.

app/models/user.rb

@@ -1672,6 +1672,16 @@ class User < ApplicationRecord
     callouts.any?
   end
 
+  def gitlab_employee?
+    strong_memoize(:gitlab_employee) do
+      if Gitlab.com?
+        Mail::Address.new(email).domain == "gitlab.com"
+      else
+        false
+      end
+    end
+  end
+
   # @deprecated
   alias_method :owned_or_masters_groups, :owned_or_maintainers_groups
 

lib/api/entities/discussion.rb

@@ -5,7 +5,7 @@ module API
     class Discussion < Grape::Entity
       expose :id
       expose :individual_note?, as: :individual_note
-      expose :notes, using: Entities::Note
+      expose :notes, using: Entities::NoteWithGitlabEmployeeBadge
     end
   end
 end

lib/api/entities/note_with_gitlab_employee_badge.rb

+# frozen_string_literal: true
+
+module API
+  module Entities
+    class NoteWithGitlabEmployeeBadge < Note
+      expose :author, using: Entities::UserWithGitlabEmployeeBadge
+      expose :resolved_by, using: Entities::UserWithGitlabEmployeeBadge, if: ->(note, options) { note.resolvable? }
+    end
+  end
+end

lib/api/entities/user_with_gitlab_employee_badge.rb

+# frozen_string_literal: true
+
+module API
+  module Entities
+    class UserWithGitlabEmployeeBadge < UserBasic
+      expose :gitlab_employee?, as: :is_gitlab_employee, if: ->(user, options) { ::Feature.enabled?(:gitlab_employee_badge) && user.gitlab_employee? }
+    end
+  end
+end

spec/fixtures/api/schemas/entities/user.json

@@ -17,7 +17,8 @@
     "path": { "type": "string" },
     "name": { "type": "string" },
     "username": { "type": "string" },
-    "status_tooltip_html": { "$ref": "../types/nullable_string.json" }
+    "status_tooltip_html": { "$ref": "../types/nullable_string.json" },
+    "is_gitlab_employee": { "type": "boolean" }
   },
   "additionalProperties": false
 }

spec/models/user_spec.rb

@@ -4335,4 +4335,27 @@ describe User, :do_not_mock_admin_mode do
       it { expect(user.user_detail).to be_persisted }
     end
   end
+
+  describe '#gitlab_employee?' do
+    using RSpec::Parameterized::TableSyntax
+
+    subject { user.gitlab_employee? }
+
+    where(:email, :is_com, :expected_result) do
+      'test@gitlab.com'   | true  | true
+      'test@example.com'  | true  | false
+      'test@gitlab.com'   | false | false
+      'test@example.com'  | false | false
+    end
+
+    with_them do
+      let(:user) { build(:user, email: email) }
+
+      before do
+        allow(Gitlab).to receive(:com?).and_return(is_com)
+      end
+
+      it { is_expected.to be expected_result }
+    end
+  end
 end

spec/support/shared_examples/requests/api/discussions_shared_examples.rb

@@ -55,6 +55,58 @@ RSpec.shared_examples 'with cross-reference system notes' do
 end
 
 RSpec.shared_examples 'discussions API' do |parent_type, noteable_type, id_name, can_reply_to_individual_notes: false|
+  shared_examples 'is_gitlab_employee attribute presence' do
+    subject { get api("/#{parent_type}/#{parent.id}/#{noteable_type}/#{noteable[id_name]}/discussions", user) }
+
+    before do
+      allow(Gitlab).to receive(:com?).and_return(true)
+      user.update(email: email)
+      user.confirm
+    end
+
+    context 'when author is a gitlab employee' do
+      let(:email) { 'test@gitlab.com' }
+
+      it 'returns is_gitlab_employee as true' do
+        subject
+
+        expect(json_response.first["notes"].first["author"]['is_gitlab_employee']).to be true
+      end
+    end
+
+    shared_examples 'non inclusion of gitlab employee badge' do
+      it 'does not include is_gitlab_employee attribute' do
+        subject
+
+        expect(json_response.first["notes"].first["author"]).not_to have_key('is_gitlab_employee')
+      end
+    end
+
+    context 'when author is not a gitlab employee' do
+      let(:email) { 'test@example.com' }
+
+      it_behaves_like 'non inclusion of gitlab employee badge'
+    end
+
+    describe 'when feature flag is disabled' do
+      before do
+        stub_feature_flags(gitlab_employee_badge: false)
+      end
+
+      context 'when author is a gitlab employee' do
+        let(:email) { 'test@gitlab.com' }
+
+        it_behaves_like 'non inclusion of gitlab employee badge'
+      end
+
+      context 'when author is not a gitlab employee' do
+        let(:email) { 'test@example.com' }
+
+        it_behaves_like 'non inclusion of gitlab employee badge'
+      end
+    end
+  end
+
   describe "GET /#{parent_type}/:id/#{noteable_type}/:noteable_id/discussions" do
     it "returns an array of discussions" do
       get api("/#{parent_type}/#{parent.id}/#{noteable_type}/#{noteable[id_name]}/discussions", user)
@@ -78,6 +130,8 @@ RSpec.shared_examples 'discussions API' do |parent_type, noteable_type, id_name,
 
       expect(response).to have_gitlab_http_status(:not_found)
     end
+
+    it_behaves_like 'is_gitlab_employee attribute presence'
   end
 
   describe "GET /#{parent_type}/:id/#{noteable_type}/:noteable_id/discussions/:discussion_id" do
@@ -196,6 +250,8 @@ RSpec.shared_examples 'discussions API' do |parent_type, noteable_type, id_name,
         end
       end
     end
+
+    it_behaves_like 'is_gitlab_employee attribute presence'
   end
 
   describe "POST /#{parent_type}/:id/#{noteable_type}/:noteable_id/discussions/:discussion_id/notes" do