Add tests for CustomEmoji#local? and #object_type (#5621)

spec/models/custom_emoji_spec.rb

 require 'rails_helper'
 
 RSpec.describe CustomEmoji, type: :model do
+  describe '#local?' do
+    let(:custom_emoji) { Fabricate(:custom_emoji, domain: domain) }
+
+    subject { custom_emoji.local? }
+
+    context 'domain is nil' do
+      let(:domain) { nil }
+
+      it 'returns true' do
+        is_expected.to be true
+      end
+    end
+
+    context 'domain is present' do
+      let(:domain) { 'example.com' }
+
+      it 'returns false' do
+        is_expected.to be false
+      end
+    end
+  end
+
+  describe '#object_type' do
+    it 'returns :emoji' do
+      custom_emoji = Fabricate(:custom_emoji)
+      expect(custom_emoji.object_type).to be :emoji
+    end
+  end
+
   describe '.from_text' do
     let!(:emojo) { Fabricate(:custom_emoji) }