Logstash filter will be growing up forever. You need test before dead.
This repository includes a sample rspec test for logstash filter. Test is executed on Docker container 🐳. So all you need to prepare is docker environment. If you replace conf/filter.conf and spec/filter_spec.rb with your own, you can test your filter. Feel free to fork or copy this repository.
To run sample test,
$ ./run.sh