Add survey related tests

spec/models/survey_submission_spec.rb

@@ -0,0 +1,16 @@
+require 'spec_helper'
+
+describe SurveySubmission do
+  subject { create(:survey_submission) }
+
+  describe 'association' do
+    it { is_expected.to belong_to(:survey) }
+    it { is_expected.to belong_to(:user) }
+    it { is_expected.to have_many(:survey_replies).through(:user) }
+    it { is_expected.to accept_nested_attributes_for(:survey_replies) }
+  end
+
+  describe 'validation' do
+    it { is_expected.to validate_uniqueness_of(:user_id).scoped_to(:survey_id) }
+  end
+end