add stats download tests

app/controllers/stats_controller.rb

@@ -129,7 +129,7 @@ def to_keyword(param)
 
   def format(data, name)
     respond_to do |format|
-      format.csv { send_data data.to_csv }
+      format.csv { send_data data.to_csv, type: 'text/csv' }
       format.json { send_data data.to_json, type: 'application/json; header=present', disposition: "attachment; filename=#{name}.json" }
     end
   end

app/models/concerns/raw_stats.rb

@@ -1,3 +1,4 @@
+require 'csv'
 module RawStats
   extend ActiveSupport::Concern
 

test/functional/stats_controller_test.rb

@@ -1,9 +1,11 @@
 require 'test_helper'
+require 'csv'
 
 class StatsControllerTest < ActionController::TestCase
   def setup
     @start = 1.month.ago.to_time
     @end = Date.today.to_time
+    @stats =  [:notes, :comments, :users, :wikis, :questions, :answers]
   end
 
   test 'should assign correct value to graph_notes on GET stats' do
@@ -45,4 +47,25 @@ def setup
     assert_response :success
   end
 
+  def csv_stats_download
+    @stats.each do |action|
+      test "should download #{action} as csv" do
+        get action, params: { format: 'csv' }
+        assert_response :success
+        assert_equal "text/csv", response.content_type
+        assert_equal "attachment", response['Content-Disposition']
+      end
+    end
+  end
+
+  def json_stats_downloads
+    @stats.each do |action|
+      test "should download #{action} as json" do
+        get action, params: { format: 'json' }
+        assert_response :success
+        assert_equal "application/json", response.content_type
+        assert_equal "attachment", response['Content-Disposition']
+      end
+    end
+  end
 end