FIX: Topics not always properly shown (#11)

There was a bug with the logic in how we were checking for matching tags
and categories in KE settings. If only tags were set, topics would not
show.

app/controllers/knowledge_explorer/knowledge_explorer_controller.rb

@@ -55,6 +55,7 @@ module KnowledgeExplorer
 
     def topic_in_explorer(category, tags)
       category_match = KnowledgeExplorer::Query.categories.include?(category.to_s)
+      tags = tags.pluck(:name)
       tag_match = KnowledgeExplorer::Query.tags.any? { |tag| tags.include?(tag) }
 
       category_match || tag_match

spec/requests/knowledge_explorer_controller_spec.rb

@@ -154,6 +154,22 @@ describe KnowledgeExplorer::KnowledgeExplorerController do
 
         expect(response.parsed_body['topic']).to be_blank
       end
+
+      it 'should return a KE topic when only tags are added to settings' do
+        SiteSetting.knowledge_explorer_categories = nil
+
+        get "/docs.json?topic=#{topic.id}"
+
+        expect(response.parsed_body['topic']['id']).to eq(topic.id)
+      end
+
+      it 'should return a KE topic when only categories are added to settings' do
+        SiteSetting.knowledge_explorer_tags = nil
+
+        get "/docs.json?topic=#{topic.id}"
+
+        expect(response.parsed_body['topic']['id']).to eq(topic.id)
+      end
     end
   end
 end