Add tests for `namespaces_as_json`

Adds related rspec tests for the helper
method `namespaces_as_json`

spec/helpers/namespaces_helper_spec.rb

@@ -45,6 +45,39 @@ RSpec.describe NamespacesHelper do
     user_group.add_owner(user)
   end
 
+  describe '#namespaces_as_json' do
+    let(:result) { helper.namespaces_as_json(user) }
+
+    before do
+      allow(helper).to receive(:current_user).and_return(user)
+    end
+
+    it 'returns the user\'s groups' do
+      json_data = Gitlab::Json.parse(result)
+
+      expect(result).to include('group')
+      expect(json_data['group']).to include(
+        "id" => user_group.id,
+        "name" => user_group.name,
+        "display_path" => user_group.full_path,
+        "human_name" => user_group.human_name
+      )
+    end
+
+    it 'returns the user\'s namespace' do
+      user_namespace = user.namespace
+      json_data = Gitlab::Json.parse(result)
+
+      expect(result).to include('user')
+      expect(json_data['user']).to include(
+        "id" => user_namespace.id,
+        "name" => user_namespace.name,
+        "display_path" => user_namespace.full_path,
+        "human_name" => user_namespace.human_name
+      )
+    end
+  end
+
   describe '#namespaces_options' do
     context 'when admin mode is enabled', :enable_admin_mode do
       it 'returns groups without being a member for admin' do