Add missing .length on gsub matcher

Author: erimicel

lib/fcm.rb

@@ -162,7 +162,7 @@ def get_instance_id_info(iid_token, options = {})
   end
 
   def send_to_topic(topic, options = {})
-    if topic.gsub(TOPIC_REGEX, '').zero?
+    if topic.gsub(TOPIC_REGEX, '').length.zero?
       body = { 'message': { 'topic': topic }.merge(options) }
 
       for_uri(BASE_URI_V1) do |connection|

spec/fcm_spec.rb

@@ -207,6 +207,15 @@
       )
       stub_fcm_send_to_topic_request.should have_been_made.times(1)
     end
+
+    context "when topic is invalid" do
+      let(:topic) { '/topics/news$' }
+
+      it 'should raise error' do
+        client.send_to_topic(topic, options)
+        stub_fcm_send_to_topic_request.should_not have_been_requested
+      end
+    end
   end
 
   describe "#send_to_topic_condition" do