logstash test config

Logstash Test Config File

##/opt/mohan/mytest.conf
input{
 stdin {}
}
filter {
## You can drive here
# My Test 
 json {
  source => "message"
 }
}
output {
 stdout {
  codec => rubydebug
 }
}

How to execute?

/opt/logstash241/bin/logstash -f /opt/mohan/mytest.conf < mydata.json