DEV: Plugins can extend ReviewableScore types. (#10156)

spec/components/plugin/instance_spec.rb

@@ -553,4 +553,39 @@ describe Plugin::Instance do
       expect(custom_emoji.group).to eq("baz")
     end
   end
+
+  describe '#replace_flags' do
+    let(:original_flags) { PostActionType.flag_settings }
+
+    it 'adds a new flag' do
+      highest_flag_id = ReviewableScore.types.values.max
+      flag_name = :new_flag
+
+      subject.replace_flags(settings: original_flags) do |settings, next_flag_id|
+        settings.add(
+          next_flag_id,
+          flag_name
+        )
+      end
+
+      expect(PostActionType.flag_settings.flag_types.keys).to include(flag_name)
+      expect(PostActionType.flag_settings.flag_types.values.max).to eq(highest_flag_id + 1)
+    end
+
+    it 'adds a new score type after adding a new flag' do
+      highest_flag_id = ReviewableScore.types.values.max
+      new_score_type = :new_score_type
+
+      subject.replace_flags(settings: original_flags, score_type_names: [new_score_type]) do |settings, next_flag_id|
+        settings.add(
+          next_flag_id,
+          :new_flag
+        )
+      end
+
+      expect(PostActionType.flag_settings.flag_types.values.max).to eq(highest_flag_id + 1)
+      expect(ReviewableScore.types.keys).to include(new_score_type)
+      expect(ReviewableScore.types.values.max).to eq(highest_flag_id + 2)
+    end
+  end
 end