Ensure we don't run `$redis.keys` in production.

app/services/random_topic_selector.rb

@@ -77,10 +77,6 @@ class RandomTopicSelector
     results
   end
 
-  def self.clear_cache!
-    $redis.keys('random_topic_cache*').each{|k| $redis.del k}
-  end
-
   def self.cache_key(category=nil)
     "random_topic_cache_#{category.try(:id)}"
   end

spec/components/topic_query_spec.rb

@@ -642,9 +642,12 @@ describe TopicQuery do
   end
 
   context 'suggested_for' do
+    def clear_cache!
+      $redis.keys('random_topic_cache*').each{|k| $redis.del k}
+    end
 
     before do
-      RandomTopicSelector.clear_cache!
+      clear_cache!
     end
 
     context 'when anonymous' do
@@ -674,7 +677,7 @@ describe TopicQuery do
       let(:suggested_topics) {
         tt = topic
         # lets clear cache once category is created - working around caching is hard
-        RandomTopicSelector.clear_cache!
+        clear_cache!
         topic_query.list_suggested_for(tt).topics.map{|t| t.id}
       }
 
@@ -691,11 +694,11 @@ describe TopicQuery do
           SiteSetting.suggested_topics_max_days_old = 1365
           tt = topic
 
-          RandomTopicSelector.clear_cache!
+          clear_cache!
           expect(topic_query.list_suggested_for(tt).topics.length).to eq(2)
 
           SiteSetting.suggested_topics_max_days_old = 365
-          RandomTopicSelector.clear_cache!
+          clear_cache!
 
           expect(topic_query.list_suggested_for(tt).topics.length).to eq(1)
         end