Make measure titles clickable on the variance chart

spec/views/overview/index.html.erb_spec.rb

@@ -42,7 +42,10 @@ describe 'overview/index' do
   before :each do
     assign :category_presenters, []
     assign :variance_chart_row_presenters, variance_chart_row_presenters
-    assign :academic_years, []
+    @academic_year = create(:academic_year)
+    assign :academic_years, [@academic_year]
+    @district = create(:district)
+    @school = create(:school)
 
     render
   end

spec/views/overview/variance_chart.html.erb_spec.rb

@@ -1,6 +1,12 @@
 require 'rails_helper'
 
 describe 'overview/_variance_chart.html.erb' do
+  before do
+    @academic_year = create(:academic_year)
+    @district = create(:district)
+    @school = create(:school)
+  end
+
   context 'When there are scores to show' do
     subject { Nokogiri::HTML(rendered) }