Add test for `NotificationsController`

spec/controllers/notifications_controller_spec.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe NotificationsController do
+  subject { get :index, params: { type: :new } }
+
+  let(:user) { FactoryBot.create(:user) }
+
+  before do
+    sign_in(user)
+  end
+
+  context "user has no notifications" do
+    it "should show an empty list" do
+      subject
+      expect(response).to render_template(:index)
+
+      expect(controller.instance_variable_get(:@notifications)).to be_empty
+    end
+  end
+
+  context "user has notifications" do
+    let(:other_user) { FactoryBot.create(:user) }
+    let(:another_user) { FactoryBot.create(:user) }
+    let(:question) { FactoryBot.create(:question, user: user) }
+    let!(:answer) { FactoryBot.create(:answer, question: question, user: other_user) }
+    let!(:subscription) { Subscription.create(user: user, answer: answer) }
+    let!(:comment) { FactoryBot.create(:comment, answer: answer, user: other_user) }
+
+    it "should show a list of notifications" do
+      subject
+      expect(response).to render_template(:index)
+      expect(controller.instance_variable_get(:@notifications)).to have_attributes(size: 2)
+    end
+  end
+end