Add tests for Namespace#full_name method

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

spec/models/namespace_spec.rb

@@ -133,6 +133,14 @@ describe Namespace, models: true do
     it { expect(nested_group.full_path).to eq("#{group.path}/#{nested_group.path}") }
   end
 
+  describe '#full_name' do
+    let(:group) { create(:group) }
+    let(:nested_group) { create(:group, parent: group) }
+
+    it { expect(group.full_name).to eq(group.name) }
+    it { expect(nested_group.full_name).to eq("#{group.name} / #{nested_group.name}") }
+  end
+
   describe '#parents' do
     let(:group) { create(:group) }
     let(:nested_group) { create(:group, parent: group) }