Test filebeat and logstash independently

My production logstash pipeline receives events from the filebeat agent using the "beats" input plugin.
For unit testing, I would like to be able to decouple filebeat and logstash. I was thinking I would generate a file output from filebeat and then use that file as the input for logstash for my logstash test. That would mean I only need to alter the input section of my logstash pipeline when running in test mode. It's not clear to me how to configure the logstash input for this to work.
Or, if there is a simpler way to accomplish my goal, please let me know.

Thanks

Never mind. I just needed to use the json codec in my file input plugin in Logstash and not use pretty print in my file output plugin in filebeat.