Refuse non-JSON queries on API

app/controllers/api/application_controller.rb

@@ -4,6 +4,7 @@ module API
     skip_before_filter :authenticate!, only: :cor_preflight
 
     before_filter :cor_filter
+    before_filter :json_filter!
 
     def cor_filter
       headers['Access-Control-Allow-Origin'] = request.headers['Origin'] ?
@@ -28,5 +29,9 @@ module API
     def authenticate!
       head :unauthorized if current_user.nil?
     end
+
+    def json_filter!
+      head :not_acceptable if request.format != :json
+    end
   end
 end

spec/integration/api/application_spec.rb

@@ -10,4 +10,12 @@ describe 'API application' do
       expect(json).to eq(pong: 'ok')
     end
   end
+
+  describe 'formats handling' do
+    it 'responds with a 406 when request format is not JSON' do
+      get api_ping_path, format: :xml
+      expect(response.status).to be 406
+      expect(response.body).to be_empty
+    end
+  end
 end