Add changelog and metrics definition warn in Danger

danger/telemetry/Dangerfile

@@ -8,6 +8,11 @@ Please check the ~telemetry [guide](https://docs.gitlab.com/ee/development/telem
 
 MSG
 
+UPDATE_METRICS_DEFINITIONS_MESSAGE = <<~MSG
+  When adding, changing, or updating metrics, please update the [Usage Statistics definition table](https://docs.gitlab.com/ee/development/telemetry/usage_ping.html#usage-statistics-definitions).
+
+MSG
+
 tracking_files = [
   'lib/gitlab/tracking.rb',
   'spec/lib/gitlab/tracking_spec.rb',
@@ -17,13 +22,14 @@ tracking_files = [
   'spec/frontend/tracking_spec.js'
 ]
 
-usage_data_changed_files = git.modified_files.grep(%r{usage_data})
+usage_data_changed_files = helper.changed_files(/usage_data/)
 snowplow_events_changed_files = git.modified_files & tracking_files
 
 changed_files = (usage_data_changed_files + snowplow_events_changed_files)
 
 if changed_files.any?
   warn format(TELEMETRY_CHANGED_FILES_MESSAGE, changed_files: helper.markdown_list(changed_files))
+  warn format(UPDATE_METRICS_DEFINITIONS_MESSAGE) unless helper.changed_files(/usage_ping\.md/).any?
 
   telemetry_labels = ['telemetry']
   telemetry_labels << 'telemetry::review pending' unless helper.mr_has_labels?('telemetry::reviewed')

lib/gitlab/danger/helper.rb

@@ -250,6 +250,10 @@ module Gitlab
         "/label #{labels_list(labels, sep: ' ')}"
       end
 
+      def changed_files(regex)
+        all_changed_files.grep(regex)
+      end
+
       private
 
       def has_database_scoped_labels?(current_mr_labels)

spec/lib/gitlab/danger/changelog_spec.rb

@@ -57,6 +57,24 @@ RSpec.describe Gitlab::Danger::Changelog do
         is_expected.to be_truthy
       end
     end
+
+    context 'when MR contains a category that require changelog and a category that require no changelog with changelog label' do
+      let(:changes_by_category) { { category_with_changelog => nil, category_without_changelog => nil } }
+      let(:mr_labels) { ['feature'] }
+
+      it 'is truthy' do
+        is_expected.to be_truthy
+      end
+    end
+
+    context 'when MR contains a category that require changelog and a category that require no changelog with no changelog label' do
+      let(:changes_by_category) { { category_with_changelog => nil, category_without_changelog => nil } }
+      let(:mr_labels) { ['tooling'] }
+
+      it 'is truthy' do
+        is_expected.to be_falsey
+      end
+    end
   end
 
   describe '#found' do

spec/lib/gitlab/danger/helper_spec.rb

@@ -76,6 +76,14 @@ RSpec.describe Gitlab::Danger::Helper do
     end
   end
 
+  describe "changed_files" do
+    it 'returns list of changed files matching given regex' do
+      expect(helper).to receive(:all_changed_files).and_return(%w[migration.rb usage_data.rb])
+
+      expect(helper.changed_files(/usage_data/)).to contain_exactly('usage_data.rb')
+    end
+  end
+
   describe '#all_ee_changes' do
     subject { helper.all_ee_changes }