Fix potential false positives from using expect not_to

Author: cacheflow

spec/fcm_spec.rb

@@ -26,7 +26,7 @@
   end
 
   let(:large_file_name) do
-    Array.new(1021) { "a" }.join("") + ".txt"
+    Array.new(1021) { 'a' }.join('') + '.txt'
   end
 
   let(:creds_error) do
@@ -81,7 +81,9 @@
       temp_file.write(json_credentials)
       fcm_with_temp_file = FCM.new(temp_file)
 
-      expect { fcm_with_temp_file.__send__(:json_key) }.not_to raise_error(creds_error)
+      expect do 
+        fcm_with_temp_file
+      end.not_to raise_error
       temp_file.close
       temp_file.unlink
     end